With this sketch of Geological Chronolog_Geology and Revelation or, the Ancient History of the Earth, considered in the geological facts and revealed religion.

fully realize to our minds the story we are told about the formation of

the Earth’s Crust. In the earliest age to which Geologists can trace

back the history of the Aqueous Rocks--for they do not profess to trace

it back to the beginning--this Globe of ours was, as it is now, partly

covered with water, and partly dry land. The formation of stratified

rocks went on in that age, as it is still going on, chiefly over those

areas that were under water--not indeed throughout the entire extent of

such areas, but over certain portions of them to which mineral matter

happened to be carried by the action of natural causes. And the Earth

was peopled then as now, though with animals and plants very different

from those by which we are surrounded at the present day. Some of these

happened to escape destruction, and to be embedded in the deposits of

that far distant age, and have thus been preserved even to our time.

And these strata with their Fossils are the same that we now group

together under the title of the Laurentian Formation: which being the

oldest group of stratified rocks we can recognize in the depths of the

Earth’s Crust, occupies the lowest position in our table of Chronology.

Ages rolled on; and the Crust of the Earth was moved from within by

some giant force, the bed of the ocean was lifted up in one place,

islands and continents were submerged in another, and so the outlines

of land and water were changed. With this change the old forms of life

passed away; a new creation came in; and the Laurentian period gave

place to the Cambrian. But the order of nature was still the same as

before. The deposition of stratified rocks still continued, though the

areas of deposition were, in many cases, shifted from one locality to

another. And the organic life that flourished in the Cambrian times

left its memorials behind it buried in the Cambrian rocks. Then that

age, too, came to an end, and gave place in its turn to the Silurian:

and this was, again, followed by the Devonian. Thus one period

succeeded to another in the order set forth in our table; and every

part of the globe was, in the course of ages, more than once submerged,

and covered with the deposits of more than one age, and enriched with

the Organic Remains of more than one creation.

As we advance upward in the series of Formations we soon perceive that

the Fossil Remains, which, in the earlier groups were scanty enough,

become profusely abundant, until even the unpractised eye cannot

fail to mark the peculiar character of each successive period;--the

exuberant vegetation of the Carboniferous, with its luxuriant herbage

and its tangled forests, its huge pines, its tall tree-ferns, and its

stately araucarias: the enormous creeping monsters of the Jurassic,

the ichthyosaurs, the megalosaurs, the iguanodons, which filled its

seas, or crowded its plains, or haunted its rivers; and higher up in

the scale, the colossal quadrupeds of the Miocene and the Pliocene, the

mammoths, the mastodons, the megatheriums, which begin to approximate

more closely to the organic types of our own age. But amidst these

various forms of life, the eye looks in vain for any relic of human

kind. No bone of man, no trace of human intelligence, is to be found

in any bed of rock that belongs to the Primary, Secondary, or Tertiary

Formations. It is only when we have passed all these, and come to the

latest formation of the whole series, nay, it is only in the uppermost

beds of this Formation, that we meet, for the first time, with human

bones, and the works of human art.

Thus it appears pretty plain, even from the testimony of Geology, that

man was the last work of the creation; and that, if the world is old,

the human race is comparatively young. These broken and imperfect

records, which have been so curiously preserved in the Crust of the

Earth, carry us back to an antiquity which may not be measured by

years and centuries, and then set before us, as in a palpable form,

how the tender herbage appeared, and the fruit-tree yielding fruit

according to its kind; and how the Earth was afterward peopled with

great creeping things, and winged fowl, and the cattle, and the beasts

of the field; and then, at length, they disclose to us how, last of

all, man appeared, to whom all these things seem to tend, and who was

to have dominion over the fish of the sea, and the fowl of the air, and

every living thing that moveth upon the earth. We do not mean to dwell

just now upon this view of the history of creation so clearly displayed

in the records of Geology. But we shall return to it hereafter when we

come in the sequel to consider how admirably the genuine truths of this

science fit in with the inspired narrative of Moses.

It may here, very naturally, be asked, if the records of Geology

give us any information as to the manner in which each period of

animal and vegetable life was brought to an end? Did the old organic

forms gradually die out, and the new gradually come in to take their

places? or were the one suddenly extinguished and the others as

suddenly produced? This question has been a subject of controversy

among Geologists themselves; and therefore it is somewhat outside our

scope, since we propose to exhibit only that more general outline of

Geological theory which is accepted by all. Nevertheless, as it is a

question that must needs occur to the mind of every reader, it seems to

call for a few words of explanation as we pass along. In the early days

of Geology, it was commonly held that each great period was brought

to an end by a sudden and violent convulsion of Nature. The Crust of

the Earth was burst open in many places all at once; the bottom of the

ocean was upheaved with a tremendous shock; the waters, driven from

their accustomed bed, rushed with furious impetuosity over islands and

continents; and the whole existing creation perished in a universal

deluge. Then succeeded an interval of chaotic confusion, and when at

length the waters subsided, and dry land again appeared, a new age

in the history of the Globe was ushered in, and the Earth was again

peopled by a new creation.

But this old theory has gradually given way as the Stratified Rocks

have been more and more fully examined, and at the present day it

is almost universally abandoned. Geologists have observed that the

same species of Fossil Remains which prevail in the upper beds of one

Formation, are met with also in the lower beds of the next, though in

less numbers and mixed up with new species; and that, as we ascend

higher and higher into the later Formation, the old species gradually

become more and more scarce, while the new gradually become more and

more numerous; until at length the characteristic forms of one age

have disappeared altogether, and those of the succeeding age have

attained their full development.

For this important fact, which was brought to light within the last

half century, we are mainly indebted to the unwearied researches and

great ability of Sir Charles Lyell. Speaking of the Formations of the

Tertiary Epoch, to which, as is well known, he has principally devoted

himself, this distinguished writer thus sums up the result of his long

investigation:--“In passing from the older to the newer members of

the Tertiary system we meet with many chasms, but none which separate

entirely, by a broad line of demarkation, one state of the organic

world from another. There are no signs of an abrupt termination of one

fauna and flora, and the starting into life of new and wholly distinct

forms. Although we are far from being able to demonstrate geologically

an insensible transition from the Eocene to the Miocene, or even from

the latter to the recent fauna, yet the more we enlarge and perfect our

general survey, the more nearly do we approximate to such a continuous

series, and the more gradually are we conducted from times when many of

the genera and nearly all the species were extinct, to those in which

scarcely a single species flourished which we do not know to exist at

present.”[86] Hence he concludes, and his conclusion is now the common

doctrine of Geologists, that the extinction and creation of species has

been “the result of a slow and gradual change in the organic world.”[87]

It was long argued against this view, that we often meet, especially

in the Primary and Secondary Formations, two groups of strata in

immediate contact, in which there is a perfectly sudden transition

from one set of Fossil Remains to another altogether different. Each

group contains a countless variety of species, and yet there is not a

single species common to the two. Does it not appear that in such a

case the organic life of one period was suddenly destroyed, and that

of the next as suddenly introduced? Not so; there is one link wanting

in the argument. It must be shown that these two strata which are

now in _immediate contact_ were originally deposited in _immediate

succession_. But this it is impossible to prove: nay, it must needs be

very often false. We have before observed that the areas of deposition

were limited in every age, and were ever shifting from one locality to

another. Therefore it must have been a frequent occurrence that, after

one bed of rock was formed, the process of deposition ceased altogether

in that locality, and did not begin again for many ages. Thus a long

lapse of time often intervened between the deposition of two strata,

which were laid out one immediately above the other. Furthermore, we

have also seen that whole groups of strata may in any age be swept away

by Denudation; and then the rocks which are next deposited in that

locality, will be in immediate contact with strata indefinitely more

ancient than themselves. From these considerations it is plain that two

groups of strata which are now found in juxtaposition, may have been

deposited in two Geological ages widely remote from each other. And

consequently a sudden transition from the Organic Life of one group to

the Organic Life of the other affords no proof of a sudden transition

from the Organic Life of one Geological Period to the Organic Life of

that which next succeeded. We may observe, however, that the recent

researches, which have contributed so much to fill up the interstices

of the Geological Calendar, have conduced in no small degree to fill up

likewise some of the more remarkable gaps or chasms in the succession

of Organic Life. It is, therefore, not unreasonable to suppose that, as

our knowledge of the Earth’s Crust becomes more and more minute, the

sudden breaks in the continuity of the scale will be still further

diminished and the successive stages of gradual transition will be made

more clearly apparent.

This subject has been very happily illustrated by Sir Charles

Lyell:--“To make still more clear the supposed working of this

machinery [for the deposition of Stratified Rocks and the preservation

of Organic Remains], I shall compare it to a somewhat analogous case

that might be imagined to occur in the history of human affairs. Let

the mortality of the population of a large country represent the

successive extinction of species, and the birth of new individuals, the

introduction of new species. While these fluctuations are gradually

taking place everywhere, suppose commissioners to be appointed to

visit each province of the country in succession, taking an exact

account of the number, names, and individual peculiarities of all the

inhabitants, and leaving in each district a register containing a

record of this information. If, after the completion of one census,

another is immediately made on the same plan, and then another, there

will, at last, be a series of statistical documents in each province.

When these belonging to any one province are arranged in chronological

order, the contents of such as stand next to each other will differ

according to the length of time between the taking of each census. If,

for example, there are sixty provinces, and all the registers are made

in a single year, and renewed annually, the number of births and deaths

will be so small in proportion to the whole of the inhabitants, during

the interval between the compiling of two consecutive documents, that

the individuals described in such documents will be nearly identical;

whereas, if the survey of each of the sixty provinces occupies all the

commissioners for a whole year, so that they are unable to revisit

the same place until the expiration of sixty years, there will then

be an almost entire discordance between the persons enumerated in two

consecutive registers in the same province.

“But I must remind the reader that the case above proposed has no

pretentions to be regarded as an exact parallel to the Geological

phenomena which I desire to illustrate; for the commissioners are

supposed to visit the different provinces in rotation; whereas the

commemorating processes by which organic remains become fossilized,

although they are always shifting from one area to the other, are yet

very irregular in their movements. They may abandon and revisit many

spaces again and again, before they once approach another district; and

besides this source of irregularity, it may often happen that, while

the depositing process is suspended, Denudation may take place, which

may be compared to the occasional destruction by fire or other causes

of some of the statistical documents before mentioned. It is evident

that where such accidents occur, the want of continuity in the series

may become indefinitely great, and that the monuments which follow next

in succession will by no means be equi-distant from each other in point

of time.

“If this train of reasoning be admitted, the occasional distinctness

of the fossil remains, in formations immediately in contact, would be

a necessary consequence of the existing laws of sedimentary deposition

and subterranean movement, accompanied by a constant mortality and

renovation or species.”[88]

There is another and a very striking fact in the succession of ancient

organic life, which claims from us a moment’s notice. As we proceed

upward through the series of Stratified Rocks, from the oldest to the

newest, we find a gradual advance in the types of animal organization

therein preserved, from the humbler and more simple forms of structure

to those of a higher and more perfect character. That form of

organization is regarded among Zoologists as the more perfect in which

there is “a greater number of organs specially devoted to particular

functions.” Now all the forms of animal life with which we are

acquainted, may be reduced to two great divisions, the Vertebrate and

the Invertebrate,--the former having a _vertebral_ or spinal column,

the latter having none: and it is agreed in conformity with the notion

set forth above, that the Vertebrate animals as a class exhibit a more

perfect organization than the Invertebrate. Again, among the Vertebrate

themselves there is a gradation; the Reptiles are ranked higher than

the Fish, the Birds higher than the Reptiles, and the Mammalia higher

again than the Birds.

All this we learn from Zoologists, who have pursued their

investigations without any reference whatever to the science of

Geology. It is, therefore, not a little remarkable that we should

discover this very order and gradation of animal life in the successive

groups of Stratified Rocks. All the Remains hitherto discovered in the

earliest Geological Formations belong to Invertebrate animals, while

the Vertebrate, which appear for the first time in the latter part

of the Silurian Period, are, from that age on, more and more fully

developed down to the present day, and now constitute, if not the most

numerous, at least the most important part of the animal creation.

Moreover, it is to be observed that the Vertebrate animals do not all

make their appearance at once, but come in successively according to

the same scale of organic perfection,--the Fish appearing first, then

the Reptiles, then the Birds, and lastly the Mammalia. Even among

the Mammalia a well-defined order of progressive succession has been

observed, which finally culminates in the appearance of Man, the last

created and the most perfect of animals.

[Illustration: TABLE OF GEOLOGICAL FORMATIONS,

SHOWING THE FIRST APPEARANCE ON THE EARTH OF THE VARIOUS FORMS OF

ANIMAL LIFE.]

This remarkable succession of animal life in the history of the

Earth’s Crust will be more readily understood by means of the annexed

Table. The remains of Invertebrate animals have been traced as far

back as the Lower Laurentian Rocks. The Vertebrate first become

manifest in the Ludlow beds of the Upper Silurian; where they are

represented by the bones of Fish, the lowest class belonging to the

Province of Vertebrates. Next in order come the Reptiles: the oldest

known Reptile having been found in the Coal Measures of Saarbrück

between Strasburg and Treves. The skeletons of Birds are rare in the

Stratified Rocks. It is supposed that their powers of flight have in

all ages secured them, to great a extent, from being carried away by

floods, like other land animals, and buried in the sedimentary deposits

of rivers and estuaries. Nevertheless their presence in the ancient

world is frequently attested by their footsteps, impressed originally

on the sandy beach, and still preserved now that the soft sand has

been converted into solid rock. Such traces have been discovered in

great abundance on the New Red Sandstone of the Connecticut River in

America; and afford the earliest evidence we possess in the records

of Geology regarding the existence of the feathered tribe. This group

of strata belongs to the lower Trias. In the higher beds of the same

Formation we meet with the first relic of ancient Mammals. It was found

near Stuttgardt, in 1847, and belongs to the more imperfect form of

Mammalian life, the Non-Placental. Similar remains have been since

discovered in the Upper Trias of Somersetshire. The Placental, or more

perfect form of animal life in the same class, first appears in the

Eocene Formation: and the bones of Man, the highest of the Placental,

are found for the first time in the upper deposits of the Post-Tertiary

Age.

Let it be remembered that we are here but stating the facts which have

been hitherto brought to light by the researches of Geologists. It

may be, it is indeed most probable, that new discoveries will lead to

numerous modifications in our Table. There is no reason to suppose that

Geologists have yet exhumed the earliest remains of Vertebrates or

Invertebrates preserved in the Crust of the Earth: that Fish may not

hereafter be traced back beyond the Silurian, or Reptiles beyond the

Carboniferous Period: that Birds may not be found among the Primary

Rocks, and Placentals among the Secondary. But in a science which

depends mainly upon observation, it is better to register the facts

we have than to speculate idly about those we have not. And, having

registered them, we cannot fail to be struck with the succession of

animal life on the Earth, to which they seem to point. It is certainly

deserving of notice that, as far as the Organic Remains hitherto

discovered may be taken as a guide, Invertebrates and Vertebrates,

Fish, Reptiles, Birds, and Mammals, Non-Placentals and Placentals,

follow one another in the ascending series of Geological Formations

exactly in the same order as they follow one another in the ascending

scale of Zoological Classification.

* * * * *

And so Geologists go on ever searching out new phenomena, and grouping

them together into classes, until from particular facts they lead us

to general truths. Then starting with these general truths as the

groundwork of their science, they proceed to sketch out the Natural

History of our Globe from the remotest ages of the past down to

the present time. They first study the stratified deposits of each

succeeding age, and analyze the Fossil Remains embedded therein;

afterward they make their inferences, and they compile their history.

They describe the forms, the character, the habits, of the plants

and animals that flourished of old in this world of ours; they tell

us where the deep sea rolled its waves in each succeeding age, and

where the dry land appeared; they point out the Deltas of its ancient

rivers, they measure the breadth of its Estuaries, they trace the

course of its Glaciers, they mark the outlines of its Mountain chains.

But with these and such like speculations we are not here concerned.

Many of them are open to controversy, and not a few are at this moment

warmly disputed among Geologists themselves: besides, whether true or

false, they do not in any way affect the relations between Geology and

Revealed Religion. We shall be quite content, and it is all that our

present scope demands, if we have made intelligible the general theory

of Geological Chronology, and the kind of evidence on which it rests.

Before taking leave of this subject, however, we will venture to offer

what seems to us an interesting illustration of the principles we

have been explaining in the last two chapters;--one that will help

to confirm the conclusions for which we have been contending, and

that will also bring home to many minds the practical advantage to be

derived from a thorough knowledge and just application of Geological

science. Perhaps, too, it may help to revive the flagging attention

of our readers; for the subject of our illustration is _Coal, and the

way to find it_. In this age of manufactories and steam-engines,--when

the atmosphere of great towns is heavy with smoke, and the quiet

solitude of the country is so rudely disturbed by the shrieking of the

railway-whistle and the snorting of the sooty locomotive,--this black,

dirty mineral has acquired a value and importance, which may succeed

in rousing even the practical money-making man to pay some heed to the

lessons of science.

Coal might have been produced in any Geological Period; and in point of

fact, beds of coal have been discovered in many different Formations.

But in England, and in Western Europe generally, it has been found by

long experience that the Coal-beds of the Carboniferous Formation are

more abundant, and of better quality, than those of any other. Indeed

the beds of Coal that occur in other Formations are so thin, and of

such inferior quality, that they cannot be worked with profit. It is

therefore of the highest importance in the search for Coal, before

going to the enormous expense of sinking deep shafts, to discover

whether or no the rocks in which the search is to be made belong to

the Carboniferous Period. In this matter the more _practical man_ is

often seriously at fault. Coal-bearing strata generally consist pretty

largely of dark-colored clay, black shales, and similar deposits. This

is a fact which, as it strikes the eye, is perfectly familiar to all

who are engaged in the working of Coal mines. Hence it happens, not

unfrequently, that the practical man, when he meets with strata of this

kind, is apt at once to infer that Coal is near at hand. The Geologist,

on the contrary, knows well that such strata are not peculiar to the

Carboniferous rocks, but are often found in other Formations in which

there is no Coal at all, or at least no Coal that will repay the

expense of working; and therefore he will pronounce it most rash to

undertake costly works on the strength of these appearances. He has

learned, however, that there are certain species of animals and plants

which are found in the Carboniferous rocks and in them alone; he will

search for these in the strata which it is proposed to explore, and

by their presence or their absence he will know whether the strata in

question belong to the Carboniferous Formation or not.

Again, it will often happen that, in the midst of an extensive region

well known to abound in Coal, the rocks which appear at the surface in

one particular locality, are not wholly devoid of Coal, but exhibit no

resemblance either in mineral character or in Fossil Remains to the

Coal-bearing strata. A question then arises of the highest practical

importance. May it be that the Coal-bearing strata are spread out

beneath this uppermost bed of rocks? and is it worth the expense to

sink a shaft through the one in the hope of reaching the other? The

practical miner has no very clear or certain principles to help him

in the solution of this problem; and thus it has often happened that

thousands upon thousands of pounds have been expended in sinking shafts

to look for Coal, where, as it afterward proved, there was not the

slightest chance of finding it. Now, though Geology cannot tell if we

shall succeed in finding Coal beneath these rocks, it _can_ tell if

there is a _good chance_ of succeeding. It can tell whether there is

a reasonable hope, by penetrating into the Crust of the Earth at this

particular spot, of reaching the Carboniferous Formation; and if we can

reach the Carboniferous Formation in the midst of a Coal district, it

is very likely we shall meet with beds of Coal.

His first object will be to ascertain what is the Formation to which

the superficial rocks belong. If it be a Formation earlier in date than

the Carboniferous,--the Silurian, for instance, or the Devonian,--he

knows that it would be simply waste of money to look for Coal beneath

them; because the Carboniferous rocks cannot possibly be found

underneath the rocks of an earlier age. And so the Geologist can tell

beforehand what the mere practical man would find out only when he had

spent his money. If, on the other hand, the rocks which appear at the

surface belong to a period later than the Carboniferous, the Geologist

will not always conclude that it is expedient to sink a shaft in

search of Coal. For though the Carboniferous rocks may, in this case,

be underneath, they may be so far down in the Crust of the Earth that

we should have no chance of ever reaching them. Suppose, for example,

that the strata which appear at the surface belong to the Cretaceous

Formation. He knows from his Chronological table that the Carboniferous

age is separated from the Cretaceous by three intermediate

Periods,--the Permian, the Triassic, the Jurassic. Therefore, when he

finds the Cretaceous rocks at the surface in any locality, it is quite

possible, though of course not certain, that before the Carboniferous

Formation could be reached it would be necessary to bore through

thousands of feet of Jurassic, Triassic, and Permian rocks. And even

then there would be no certainty of meeting with the Coal-bearing

strata. Perhaps they were never deposited over this area of the earth’s

surface; or, if deposited, perhaps they were subsequently swept away

by Denudation. Hence our Geologist would reasonably conclude that, the

probable expense of the search being so enormous, and the chance of

success so remote, it would be much wiser not to make the attempt.

[Illustration]

CHAPTER XIV.

SUBTERRANEAN HEAT--ITS EXISTENCE DEMONSTRATED BY FACTS.

_Theory of stratified rocks supposes disturbances of the

earth’s crust--These disturbances ascribed by geologists

to the action of subterranean heat--The existence of

subterranean heat, and its power to move the crust of the

earth, proved by direct evidence--Supposed igneous origin of

our globe--Remarkable increase of temperature as we descend

into the earth’s crust--Hot springs--Artesian wells--Steam

issuing from crevices in the earth--The geysers of Iceland--A

glimpse at the subterranean fires--Mount Vesuvius in 1779--Vast

extent of volcanic action--Existence of subterranean heat an

established fact._

In developing the modern theory of Geology, we have all along assumed

that the Crust of the Earth has been subject to frequent disturbances

from the earliest ages of the world. Again and again, in the course

of our argument, we have talked of the bed of the sea being lifted

up, and converted into dry land; and, on the other hand, of the dry

land being submerged beneath the waters of the sea. We have not even

hesitated to suppose that these two opposite movements of upheaval and

submersion often took place by turns over the same area; nay, that

there is scarcely a region on the surface of the Globe which has not

been several times submerged, and several times again upheaved.

Yet all this has not been taken for granted without proof. Our readers

have seen what a long array of sober reasoning may be drawn out to

show that the Stratified Rocks have been, for the most part, deposited

_under water_:--first, from the nature and arrangement of the materials

which compose them; secondly, from the character of the Organic Remains

they contain. And since they are now _above water_, it is plain that

either they have been lifted or the ocean has subsided. Furthermore, if

we find, as we often do, two strata in immediate succession, the one

underneath, exhibiting the trees of an ancient forest still standing

erect with their roots attached, the other above, abounding in the

remains of aquatic animals; we must conclude that when the ancient

forest flourished this portion of the Earth’s Crust was above the

level of the sea; that afterward it was submerged, and a new deposit,

in which the marine remains were embedded, was spread out above the

earlier vegetation; and that, last of all it again emerged from the

waters, and became once more dry land. Finally, when a vertical section

of the Earth’s Crust exhibits a continued series of such strata

alternating with each other, it affords a proof that this particular

area must have been several times under water, and several times again

dry land, in the long course of ages.

These conclusions are now all but universally received among

Geologists. The Crust of the Earth, we are assured, is not that

unyielding and immovable mass which men commonly take it to be. On the

contrary, it has been from the beginning ever restless and in motion,

rising here and subsiding there, sometimes with a convulsive shock

capable of upturning, twisting, distorting hard and stubborn rocks as

if they were but flimsy layers of pliant clay; sometimes with a gentle,

undulating movement, which, while it uplifts islands and continents,

leaves the general aspect of the surface unchanged, the arrangement of

the strata undisturbed, and even the most tender Fossils unharmed.

Disturbances of this kind have been going on in various parts of the

world even within the period of history; and they may be distinctly

traced to the action of subterranean Heat. In support of a theory so

startling and unexpected, Geologists appeal to the direct evidence of

facts: and we now propose to bring some of these facts under the notice

of our readers.

At the outset, however, it is important to set forth clearly the

doctrine we hope to illustrate and confirm. With the origin of the

internal heat that prevails within the Crust of the Earth we have no

concern. This is still an unsettled point among Geologists themselves.

Some conjecture that our Globe, when first launched into space, was

in a state of igneous fusion; that is to say, that all the solid

matter of which it is composed was held in a molten condition by the

action of intense heat; that, in course of time, as this heat passed

off by radiation, the surface gradually cooled and grew hard; that

an external shell of solid rock was thus formed, which has been ever

growing thicker in proportion as the Earth has been growing cooler; and

that the actual condition of our planet is the result of this process

continued down to the present day,--a fiery mass of seething mineral

within, and a comparatively thin crust of consolidated rock without.

Others suppose that the internal heat of the Globe is developed by the

agency of chemical changes constantly going on in the depths of the

Earth; and others, again, look for a cause to the action of electricity

and magnetism. But these and such like speculations are still under

discussion, and not one of them can be regarded as anything more, at

best, than a satisfactory hypothesis. Anyhow, it is not about the

causes of internal heat that we are just now interested, but about

the fact of its existence, and the nature of its effects. Is it true

that an intense heat prevails very generally beneath the superficial

covering of the Globe? and is that heat capable of producing those

stupendous changes which are ascribed to it in our theory of Geology?

These are the questions to which we mean to devote our chief attention.

It is a very significant fact, that _the deeper we penetrate into the

Crust of the Earth, the hotter it is_. At first, no doubt, for a short

distance, the reverse is the case. When we begin to descend we find it

cooler below than above, because the further we depart from the surface

the more we are removed from the influence of the Sun. But at a certain

point--in our climate at about fifty feet below the surface--the

influence of the Sun’s heat ceases to be sensibly felt. When this limit

is passed, the temperature begins to rise, and thenceforth the deeper

we go the hotter the earth becomes.

This broad and general fact has been tested by experiments in every

part of the world, and has been found true in all countries, in

all climates, in all latitudes, whether in coal-pits, or mines, or

deep subterranean caves. “In one and the same mine,” says Sir John

Herschel,[89] “each particular depth has its own particular degree of

heat, which never varies: but the lower always the hotter; and that

not by a trifling, but what may well be called an astonishingly rapid

rate of increase,--about a degree of the thermometer additional warmth

for every ninety feet of additional depth,[90] which is about 58° per

mile!--so that, if we had a shaft sunk a mile deep, we should find in

the rock a heat of 105°, which is much hotter than the hottest summer

day ever experienced in England.” Now if the temperature continue

to increase at this rate toward the centre of the Earth, it is quite

certain that, at no very great distance from the surface, the heat

would be sufficiently intense to reduce the hardest granite and the

most refractory metals to a state of igneous fusion.

Again, every one is familiar with the existence of hot springs,

which come up from unknown depths in the Earth’s Crust, and which,

appearing as they do in almost all parts of the world, testify in

unmistakable language to the existence of internal heat. At Bath,

for instance, in England, the water comes up from the bowels of the

Earth, at a temperature of 117° Fahrenheit; and in the United States,

on the Arkansas River, there is a spring at 180°--not much below the

boiling point. This remarkable phenomenon, however, may be more closely

investigated in the case of Artesian Wells, so called from the province

of Artois, in France, where they first came into use. These wells are

formed artificially, by boring down through the superficial strata of

the Earth, sometimes to enormous depths, until water is reached. It

has been found in every case that the water coming up from these great

depths is always hot; and, furthermore, that the deeper the boring the

hotter the water. A well of this kind was sunk in 1834 at Grenelle, in

the suburbs of Paris, to a depth of more than 1800 English feet, and

the water, which rushed up with surprising force, had a temperature

of 82° Fahrenheit; whereas the mean temperature of the air in the

cellars of the Paris Observatory is only 53°. The water has ever since

continued to flow, and the temperature has never varied. At Salzwerth,

in Germany, where the boring is still deeper, being 2,144 feet, the

water which rises to the surface is 91° of our scale.

Then we have, in many countries, jets of steam which issue at a high

temperature from crevices in the Earth, and which tell of the existence

of heated water below, as plainly as the steam that escapes from the

funnel of a locomotive or from the spout of a tea-kettle. Phenomena of

this kind are very common in Italy, where they are sometimes exhibited

at intervals along a line of country twenty miles in length. But in

Iceland it is that they are displayed in the highest degree of splendor

and power. On the southwest side of that island, within a circuit of

two miles, there are nearly a hundred hot springs called Geysers, from

some of which, at intervals, immense volumes of steam and boiling water

are violently projected into the air. The Great Geyser is a natural

tube, ten feet wide, descending into the Earth to a depth of seventy

feet, and opening out above into a broad basin, from fifty to sixty

feet in diameter. This basin, as well as the tube which connects it

with the interior of the Earth, is lined with a beautifully smooth

and hard plaster of siliceous cement, and is generally filled to the

brim with water of a clear azure color, and a temperature little

below boiling point. The ordinary condition of the spring is one of

comparative repose, the water rising slowly in the tube and trickling

over the edge of the stony basin. But every few hours an eruption takes

place. Subterranean explosions are first heard, like the firing of

distant cannon; then a violent ebullition follows, clouds of steam are

given out, and jets of boiling water are cast up into the air. After a

little the disturbance ceases, and all is quiet again. Once a day, or

thereabouts, these phenomena are exhibited on a scale of extraordinary

grandeur: the explosions which announce beforehand the approaching

display are more numerous and violent than usual; then such volumes of

steam rush forth as to obscure the atmosphere for half a mile around;

and, finally, a vast column of water is projected to a height of from

one to two hundred feet, and continues for a quarter of an hour to play

like an artificial fountain. Geysers scarcely less grand and striking

are to be seen in New Zealand, from which the water is thrown up at a

temperature 214° Fahrenheit, or two degrees above boiling point.

Such are the evident symptoms of subterranean heat,--hot springs, jets

of steam, fountains of boiling water,--which are manifested unceasingly

at the surface of the Earth in every quarter of the Globe. But it is

sometimes given us to behold, as it were, the subterranean fire itself,

and to contemplate its power under a more striking and awful form. From

time to time, in the fury of its rage, the fiery element bursts asunder

the prison-house in which it is confined, and rushes forth into the

light of day; then flames are seen to issue from the surface of the

Earth, yawning chasms begin to appear on every side, the roaring of

the furnaces is heard in the depths below, clouds of red-hot cinders

are ejected high into the air, and streams of incandescent liquid rock

are poured forth from every crevice, which, rolling far away through

smiling fields and peaceful villages, carry destruction and desolation

in their track. These are the ordinary phenomena of an active volcano

during the period of eruption; and even while we write, most of them

may be witnessed actually taking place for the hundredth time, on the

historic ground of Mount Vesuvius. Our typical example, however, we

shall take from the eruption of that mountain in the year 1779. It

was not, indeed, especially remarkable for its violence or for the

catastrophes by which it was attended; but it had the good fortune

to be accurately recorded by an eye-witness, Sir William Hamilton,

who, at that time, represented the English Government at the Court of

Naples; and we are thus more minutely acquainted with all its various

circumstances than with those of any other eruption of equal importance.

For two years before, the mountain had been in a state of excitement

and disturbance. From time to time rumbling noises were heard

underground, dense masses of smoke were emitted from the crater, liquid

lava at a white heat bubbled up from crevices on the slopes of the

mountain, and through these crevices a glimpse could be had here and

there of the rocky caverns within, all “red-hot like a heated oven.”

But in the month of August, 1779, the eruption reached its climax.

About nine o’clock in the evening of Sunday the eighth, according to

the graphic description of Sir William Hamilton, “there was a loud

report, which shook the houses at Portici and its neighborhood to

such a degree as to alarm the inhabitants and drive them out into

the streets. Many windows were broken, and, as I have since seen,

walls cracked, from the concussion of the air from that explosion.

In one instant, a fountain of liquid transparent fire began to rise,

and, gradually increasing, arrived at so amazing a height, as to

strike every one who beheld it with the most awful astonishment. I

shall scarcely be credited when I assure you that, to the best of my

judgment, the height of this stupendous column of fire could not be

less than three times that of Vesuvius itself, which, you know, rises

perpendicularly near 3,700 feet above the level of the sea. Puffs of

smoke, as black as can possibly be imagined, succeeded one another

hastily, and accompanied the red-hot, transparent, and liquid lava,

interrupting its splendid brightness here and there by patches of

the darkest hue. Within these puffs of smoke, at the very moment of

their emission from the crater, I could perceive a bright but pale

electrical light playing about in zigzag lines. The liquid lava, mixed

with scoriae and stones, after having mounted, I verily believe, at

least 10,000 feet, falling perpendicularly on Vesuvius, covered its

whole cone, and part of that of Somma, and the valley between them. The

falling matter being nearly as vivid and inflamed as that which was

continually issuing fresh from the crater, formed with it a complete

body of fire, which could not be less than two miles and a half in

breadth, and of the extraordinary height above mentioned, casting a

heat to the distance of at least six miles around it. The brushwood of

the mountain of Somma was soon in a flame, which, being of a different

tint from the deep red of the matter thrown out from the Volcano,

and from the silvery blue of the electrical fire, still added to the

contrast of this most extraordinary scene. After the column of fire

continued in full force for nearly half an hour the eruption ceased at

once, and Vesuvius remained sullen and silent.”[91]

The existence, then, of intense heat within the Crust of the Earth

may be regarded as an established fact where-ever an active Volcano

appears at the surface. Now let us consider for a moment, the very

extensive scale on which these fiery engines of Nature are distributed

over the face of the Globe. First, on the great continent of America.

The whole chain of the Andes--that stupendous ridge of mountains which

stretches along the western coast of South America, from Tierra del

Fuego on the south to the isthmus of Panama on the north--is studded

over with Volcanos, most of which have been seen in active eruption

within the last 300 years. Passing the narrow isthmus of Panama, this

line of Volcanos may still be traced through Guatemala to Mexico, and

thence northward even as far as the mouth of the Columbia River. Here

is a vast volcanic region extending fully 6,000 miles in length, and

spreading out its fiery arms, we know not how far, to the right and to

the left. At Quito, just on the Equator, a branch shoots off toward the

northeast, and, passing through New Granada and Venezuela, stretches

away across the West India Islands, taking in St. Vincent, Dominica,

Guadaloupe, and many others; while, in the opposite direction, it is

certain that the volcanic action extends westward, far away beneath the

waters of the Pacific, though we have no definite means of ascertaining

where its influence ceases to be felt.

Another vast train of active Volcanos is that which skirts the eastern

and southern coasts of Asia. Commencing on the shores of Northwestern

America, it passes through the Aleutian Islands to Kamtschatka; then,

in a sort of undulating curve, it winds its course by the Kurile

Islands, the Japanese group, the Philippines, and the northeastern

extremity of the Celebes, to the Moluccas. At this point it divides

into two branches; one going in a southeasterly direction to New

Guinea, the Solomon Islands, the Friendly Islands, and New Zealand; the

other pursuing a northwesterly course through Java and Sumatra into the

Bay of Bengal.

There is a third great line of volcanic fires which has been pretty

well traced out by modern travellers, extending through China and

Tartary to the Caucasus; thence over the countries bordering the Black

Sea to the Grecian Archipelago; then on to Naples, Sicily, the Lipari

Islands, the southern part of Spain and Portugal, and the Azores.

Besides these there are numerous groups of Volcanos not apparently

linked on to any regular volcanic chain, nor reduced as yet by

scientific men to any general system; Mount Hecla, for instance, in

Iceland, the Mountains of the Moon in Central Africa, Owhyhee in the

Sandwich Islands, and many others rising up irregularly from the broad

waters of the Pacific.

From this brief outline some idea may be formed of the magnificent

scale on which volcanic agency is developed within the Crust of the

Earth. It must be remembered, however, that any estimate based upon

the enumeration we have given, would be, in all probability, far

below the truth; for we have mentioned those Volcanos only which

have attracted the notice of scientific men, or which have chanced

to fall under the observation of travellers. Many others, doubtless,

must exist in regions not yet explored, and in the profound depths

of the seas and oceans, which cover nearly two-thirds of the area

of our planet. Moreover, we have said nothing at all of _extinct_

Volcanos--such as those of Auvergne in France, and of the Rocky

Mountains in America--which have not been in active operation within

historical times; but in which, nevertheless, the hardened streams of

lava, the volcanic ashes, and the cone-shaped mountains terminating in

hollow craters, tell the story of eruptions in bygone ages, not less

clearly than the blackened walls and charred timbers of some stately

building bear witness to the passing wayfarer of a long extinguished

conflagration.

We contend, therefore, that the doctrine of intense subterranean heat

is not a wild conjecture, but is based on a solid groundwork of facts.

First, there is presumptive evidence. In every deep mine, in every deep

sinking of whatever kind, the heat of the earth increases rapidly as we

descend. Hot water comes from great depths, and never cold. Sometimes

it is boiling: sometimes it has been converted into steam. All this is

found to be the case universally, whenever an opportunity has occurred

for making the trial; and it seems to afford a strong presumption that

if one could go still deeper, the heat would be found yet more intense,

and would at length be capable of reducing to a liquid state the solid

materials of which the earth is composed. Next, there is the direct

testimony of our senses. A channel is opened from the depths below,

flames are seen, red-hot cinders are cast up, and molten rock is poured

out over the surface of the Earth in a liquid stream of fire. This

evidence, however, though direct and conclusive as far as it goes, is

not universal. It proves that an intense white heat prevails within the

Crust of the Earth, not everywhere, but at least in those numerous and

extensive regions where active Volcanos exist. So stands the case, as

it seems to us, for the doctrine of subterranean heat as far as regards

the fact of its existence.

[Illustration]

_CHAPTER XV._

SUBTERRANEAN HEAT--ITS POWERS ILLUSTRATED BY VOLCANOS.

_Effects of subterranean heat in the present age of the

world--Vast accumulations of solid matter from the eruptions

of volcanos--Buried cities of Pompeii and Herculaneum--Curious

relics of Roman life--Monte Nuovo--Eruption of Jorullo in the

province of Mexico--Sumbawa in the Indian Archipelago--Volcanos

of Iceland--Mountain mass of Etna the product of volcanic

eruptions--Volcanic islands--In the Atlantic--In the

Mediterranean--Santorin in the Grecian Archipelago._

Having now sufficiently demonstrated the existence of intense

subterranean heat, diffused, if not universally, at least very

generally, beneath the superficial shell of the Earth, we shall next

proceed to inquire if it is capable of effecting those physical

changes which are ascribed to it in Geology;--of producing land where

none before existed, of upheaving the solid Crust of the Earth, of

driving the ocean from its bed, of dislocating and contorting solid

masses of rock. The argument is still an appeal to facts. Such effects

as these have been produced by the agency of internal heat, under

actual observation, in the present age of the world; and it is not

unreasonable to attribute to the same cause similar phenomena in ages

gone by.

We will not run the risk of dissipating the force of this reasoning

by attempting to expand it. It will be enough for us to state the

facts: we shall leave it to our readers to estimate for themselves the

value of the argument. There are three forms, more or less distinct,

though closely associated, under which the subterranean fires have

exerted their power in modern times to disturb and modify the Physical

Geography of the Globe;--(1) the Volcano, (2) the Earthquake, (3) the

gentle Undulation of the Earth’s Crust. Of these we shall speak in

order.

In the case of Volcanos, as we have already sufficiently conveyed, the

hidden furnaces of the Earth find a vent for their surplus energies;

and when this vent is once established, that is to say, when the active

Volcano has begun to exist, it seems probable that there is little

further upheaval, properly so called, of the surface. Nevertheless,

Volcanos contribute largely to the formation of land by the vast

accumulation of ashes, mud, and lava, which they vomit forth. The

destruction of Herculaneum and Pompeii is a case in point. For eight

days successively, in the year 79, the ashes and pumice stone cast

up from the crater of Vesuvius, fell down in one unceasing shower

upon these devoted cities; while at the same time floods of water,

carrying along the fine dust and light cinders, swept down the sides

of the mountain in resistless torrents of mud, entering the houses,

penetrating into every nook and crevice, and filling even the very wine

jars in the underground cellars.

At the present moment the layers of volcanic matter beneath which

Pompeii has been slumbering for centuries, are from twelve to fourteen

feet over the tops of the houses. Loftier still is the pile that

overlies the buried Herculaneum. This city, situated nearer to the base

of the Volcano, has been exposed to the effects of many successive

eruptions; and accordingly, spread out over the mass of ashes and

pumice by which it was first overwhelmed, in the time of Pliny, we now

find alternate layers of lava and volcanic mud, together with fresh

accumulations of ashes, to a height, in many places, of 112 feet, and

nowhere less than 70. Nor was this ejected matter confined to these two

populous towns. It was scattered far and wide over the country around,

and has contributed in no small degree to that extraordinary richness

and fertility for which the soil of Naples is so justly famed.

As regards the production of land where none before existed, here is

one fact of singular significance. At the time of the eruption, in 79,

Pompeii was a seaport town to which merchantmen were wont to resort,

and a flight of steps, which still remains, led down to the water’s

edge: it is now more than a mile distant from the coast, and the tract

of land which intervenes is composed entirely of volcanic tuff and

ashes.

Gladly would we linger over the reminiscences of these luxurious and

ill-fated cities. By the removal of the ashes, Pompeii is now laid

open to view for at least one-third of its extent; and a strange

sight it is, this ancient Roman city thus risen as it were from the

grave,--risen, but yet lifeless,--with its silent streets, and its

tenantless houses, and its empty Forum. Wherever we turn we have before

us a curious and interesting picture, ghastly though it is, of the

social, political, and domestic life of those ancient times, of the

glory and the shame that hung around the last days of Pagan Rome;--in

the theatres and the temples, in the shops and the private houses, in

the graceful frescoes, in the elaborate mosaics, and, not least, in

the idle scribblings on the walls, which, with a sort of whimsical

reverence, have been spared by the destroying hand of Time. Then again,

what a host of singular relics are there to be wondered at:--articles

of domestic use and luxury, kitchen utensils and surgical instruments;

female skeletons with the ornaments and vanities of the world, rings

and bracelets and necklaces, still clinging to their charred remains;

and strangest perhaps of all, eighty-four loaves of bread, which were

put into the oven to bake 1800 years ago, and were taken out only

yesterday, with the baker’s brand upon them, and the stamp of the

baker’s elbow still freshly preserved in the centre of each. No subject

could be more tempting to a writer, none more attractive to a reader.

But our present purpose is to show the effects of Volcanos in elevating

the level of the land; and so we must turn our back on the buried

cities, and crossing the Bay of Naples, seek for a new illustration in

the formation of Monte Nuovo, a lofty hill overlooking the ancient town

of Pozzuoli.

About one o’clock at night, on Sunday, the twenty-ninth of September,

1538, flames were seen to issue from the ground close to the waters of

the beautiful bay of Baiae. After a little, a sound like thunder was

heard, the earth was rent asunder, and through the rent large stones,

red-hot cinders, volcanic mud and volumes of water, were furiously

vomited forth, which covered the whole country around, reaching even

as far as Naples, and disfiguring its palaces and public buildings.

The next morning it was found that a new mountain had been formed by

the accumulation of ejected matter around the central opening. This

mountain remains to the present day, and is called the Monte Nuovo.

In form it is a regular volcanic cone, four hundred and forty feet

high, and a mile and a half in circumference at its base, with an open

crater in the centre, which descends nearly to the level of the sea. An

eye-witness who has left us a minute account of this eruption, relates

that on the third day he went up with many people to the top of the new

hill, and looking down into the crater, saw the stones that had fallen

to the bottom, “boiling up just as a caldron of water boils on the

fire.” The same writer informs us--and it is very much to our present

purpose to note the fact--that immediately before the eruption began,

the relative position of land and sea was materially changed, the coast

was sensibly upraised, the waters retired about two hundred paces, and

multitudes of fish were raised high and dry upon the sand, a prey to

the inhabitants of Pozzuoli.[92]

The Monte Nuovo is but a type of its class. If we travel westward 8,000

miles from Naples to the more stupendous Volcanos of the New World,

we may witness the same phenomena on a still grander scale. In the

province of Mexico, there is an elevated and extensive plain called

Malpais, where for many generations the cotton plant, the indigo, and

the sugar-cane, flourished luxuriantly in a soil richly endowed with

natural gifts, and carefully cultivated by its industrious inhabitants.

Everything was going on as usual in this smiling and prosperous region,

and no one dreamed of danger, when suddenly, in the month of June,

1759, subterranean sounds were heard, attended with slight convulsions

of the earth. These symptoms of internal commotion continued until the

month of September, when they gradually died away, and tranquillity

seemed to be restored. But it was only the delusive lull that precedes

the fury of the storm. On the night of the twenty-eighth of September

the rumbling sounds were heard again more violent than before. The

inhabitants fled in consternation to a neighboring mountain, from the

summit of which they looked back with wonder and dismay upon the utter

annihilation of their homesteads and their farms. Flames broke out

over an area half a square league in extent, the earth was burst open

in many places, fragments of burning rock were thrown to prodigious

heights in the air, torrents of boiling mud flowed over the plain, and

thousands of little conical hills, called by the natives Hornitos or

Ovens, rose up from the surface of the land. Finally a vast chasm was

opened, and such quantities of ashes and fragmentary lava were ejected

as to raise up six great mountain masses, which continued to increase

during the five months that the eruption lasted. The least of these is

300 feet high, and the central one, now called Jorullo, which is still

burning, is 1600 feet above the level of the plain. When Baron Humboldt

visited this region just forty years after the eruption had ceased, the

ground was still intensely hot, and “the Hornitos were pouring forth

columns of steam twenty or thirty feet high, with a rumbling noise like

that of a steam boiler.”[93] Since that time, however, the face of the

country has become once more smiling and prosperous; the slopes of the

newly-formed hills are now clothed with vegetation, and the sugar-cane

and the indigo again flourish luxuriantly in the fertile plains below.

On the opposite side of the Globe, 10,000 miles from Mexico, we have

had, almost in our own time, an exhibition of volcanic phenomena not

less wonderful than those we have been describing. The island of

Sumbawa lies about two hundred miles to the east of Java in the Indian

Archipelago; and it belongs to that remarkable chain of Volcanos which

we have already described as stretching, with little interruption,

along the coast of Asia from Russian America to the Bay of Bengal. In

the year 1815, this island was the scene of a calamitous eruption, the

effects of which were felt over the whole of the Molucca Islands and

Java, as well as over a considerable portion of Celebes, Sumatra, and

Borneo. Indeed, so extraordinary are the incidents of this eruption,

that we might well hesitate to believe them if they had not been

collected on the spot with more than ordinary diligence, and recorded

with an almost scrupulous care. Sir Stamford Raffles, who was at

the time governor of Java, then a British possession, required all

the residents in the various districts under his authority to send

in a statement of the circumstances which occurred within their own

knowledge; and from the accounts he received in this way, combined with

other evidence, chiefly obtained from eye-witnesses, he drew up the

narrative to which we are mainly indebted for the following facts.

The explosions which accompanied this eruption were heard in Sumatra,

at a distance of 970 geographical miles; and in the opposite direction

at Ternate, a distance of 720 miles. In the neighborhood of the Volcano

itself, immense tracts of land were covered with burning lava, towns

and villages were overwhelmed, all kinds of vegetation completely

destroyed, and of 12,000 inhabitants in the province of Tomboro,

only twenty-six survived. The ashes, which were ejected in great

quantities, were carried like a vast cloud through the air, by the

southeast monsoon, for 300 miles in the direction of Java; and, still

farther to the west, we are told that they formed a floating mass in

the ocean two feet thick and several miles in extent, through which

ships with difficulty forced their way. It is recorded, too, that they

fell so thick on the island of Tombock, 100 miles away, as to cover

all the land two feet deep, destroying every particle of vegetation,

insomuch that 44,000 people perished of the famine that ensued. “I have

seen it computed,” writes Sir John Herschel, “that the quantity of

ashes and lava vomited forth in this awful eruption would have formed

three mountains the size of Mont Blanc, the highest of the Alps; and

if spread over the surface of Germany, would have covered the whole

of it two feet deep.” Finally, it appears that this eruption was

accompanied, like that of Monte Nuovo, by a permanent change in the

level of the adjoining coast; in this case, however, it was a movement,

not of upheaval, but of subsidence: the town of Tomboro sunk beneath

the ocean, which is now eighteen feet deep where there was dry land

before.[94]

Once more we will ask our readers to take a rapid flight over the map

of the world, passing, this time, from the Indian Archipelago to the

island of Iceland,--that “wonderful land of frost and fire.” Besides

the famous Volcano of Hecla, there are five others scarcely less

formidable, all of which have been in active eruption within modern

times. Of these the most celebrated is that of Skaptar Jokul. In the

year 1783, this Volcano poured forth two streams of lava, which, when

hardened, formed together one continuous layer of igneous rock, ninety

miles in length, a hundred feet in height, and from seven to fifteen

miles in breadth. The phenomena which accompanied the eruption are

thus vividly described by Sir John Herschel:--“On the tenth of May

innumerable fountains of fire were seen shooting up through the ice

and snow which covered the mountain; and the principal river, called

the Skapta, after rolling down a flood of foul and poisonous water,

disappeared. Two days after, a torrent of lava poured down into the bed

which the river had deserted. The river had run in a ravine 600 feet

deep and 200 broad. This the lava entirely filled; and not only so,

but it overflowed the surrounding country, and ran into a great lake,

from which it instantly expelled the water in an explosion of steam.

When the lake was fairly filled, the lava again overflowed and divided

into two streams, one of which covered some ancient lava fields; the

other re-entered the bed of the Skapta lower down, and presented the

astounding sight of a cataract of liquid fire pouring over what was

formerly the waterfall of Stapafoss. This was the greatest eruption on

record in Europe. It lasted in its violence till the end of August,

and closed with a violent earthquake; but for nearly the whole year a

canopy of cinder-laden cloud hung over the island: the Faroe Islands,

nay, even Shetland and the Orkneys, were deluged with ashes; and

volcanic dust and a preternatural smoke which obscured the sun, covered

all Europe as far as the Alps, over which it could not rise. The

destruction of life in Iceland was frightful: 9,000 men, 11,000 cattle,

28,000 horses, and 190,000 sheep perished; mostly by suffocation. The

lava ejected has been computed to amount in volume to more than twenty

cubic miles.”[95]

With these very significant facts before us, it is hard to resist the

conclusion that the great mountain mass of Etna, 11,000 feet high and

ninety miles in circumference, is formed entirely of volcanic matter

ejected during successive eruptions. For the whole mountain is nothing

else than a series of concentric conical layers of ashes and lava, such

as have been poured out more than once upon its existing surface in

modern times. Just, then, as Monte Nuovo was produced by an outburst

of volcanic power in a single night, and the far larger mountain of

Jorullo in the course of a few months, so may we believe that the more

stupendous Etna is the work of the same power operating through a

period of many centuries. And applying this conclusion to many other

mountains throughout the world of exactly the same structure, we come

to form no very mean estimate of the permanent changes wrought on the

physical geography of our Globe by the operations of volcanic agency.

We must remember, too, that volcanic eruptions are not confined to the

land; they often break out in the bed of the sea. In such cases the

waters are observed in a state of violent commotion, jets of steam and

sulphurous vapor are emitted, light scoriaceous matter appears floating

on the surface, and not unfrequently the volcanic cone itself slowly

rises from the depths below, and continues to grow from day to day,

until at length it becomes an island of no inconsiderable magnitude.

Sometimes when the violence of the eruption has subsided, the new

island, consisting chiefly of ashes and pumice-stone, is gradually

washed away by the action of the waves; but in the other cases, these

lighter substances are compacted together by the injection of liquid

lava, and being thus able to withstand the erosive power of the ocean,

assume the importance of permanent volcanic islands. Many examples of

the former kind are recorded within the last hundred years. In 1783 an

island was thrown up in the North Atlantic Ocean, about thirty miles to

the southwest of Iceland. It was claimed by the King of Denmark, and

called by him Nyöe or New Island; but before a year had elapsed, this

portion of his Majesty’s dominion disappeared again beneath the waves,

and the sea resumed its ancient domain. A cone-shaped island of the

same kind, called Sabrina, three hundred feet high, with a crater in

the centre, appeared amongst the Azores in 1811, but was quickly washed

away again.

A more interesting example, because the circumstances are more minutely

recorded, is the island which made its appearance in the Mediterranean,

off the southwest coast of Sicily, in the year 1831. During its brief

existence of three months, it received from contemporary writers seven

different names; but the name of Graham Island seems to be the one by

which it is most likely to be known to posterity. “About the tenth

of July,” writes Sir Charles Lyell, “John Corrao, the captain of a

Sicilian vessel, reported that, as he passed near the place, he saw a

column of water like a waterspout, sixty feet high, and eight hundred

yards in circumference, rising from the sea, and soon afterward a

dense steam in its place, which ascended to the height of 1800 feet.

The same Corrao, on his return from Girgenti, on the eighteenth of

July, found a small island, twelve feet high, with a crater in the

centre, ejecting volcanic matter and immense columns of vapor; the sea

around being covered with floating cinders and dead fish. The scoriae

were of a chocolate color, and the water, which boiled in the circular

basin, was of a dingy red. The eruption continued with great violence

to the end of the same month, at which time the island was visited by

several persons, and amongst others by Captain Swinburne, R. N., and M.

Hoffman, the Prussian Geologist.”[96] By the fourth of August the new

island is said to have attained a height of 200 feet, and to have been

three miles in circumference. Yet this was nothing more than the top of

the volcanic cone; for, a few years before, Captain W. H. Smyth, in his

survey, had found a depth of 600 feet at this very spot; and therefore

the total height from the base of the mountain must have been 800

feet. From the beginning of August it began to melt away; and at the

commencement of the following year, nothing remained of Graham Island

but a dangerous shoal.

But even of the islands that occupy a prominent place on the map of

the world, there is not wanting evidence to show that a large number

derive their origin from the action of volcanic power. Among these may

be mentioned many of the Molucca and Philippine groups, also several

in the Grecian Archipelago, and not a few of the Azores and the

Canaries,--in particular the lofty peak of Teneriffe, rising 12,000

feet above the level of the sea. In some cases, indeed, the actual

process of their birth, and of their subsequent growth and development,

has been minutely observed. A remarkable example occurs among the

Aleutian Islands already referred to. In the year 1796 a column of

smoke was seen to issue from the sea; then a small black point appeared

at the surface of the water; then flames broke out, and other volcanic

phenomena were exhibited; then the small black point grew into an

island, and the island increased in size until it was at last several

thousand feet high, and two or three miles in circumference. And such

it remains to the present day.

[Illustration: Fig. 28.--Bird’s-eye view of Santorin during the

volcanic eruption of February, 1866. (Lyell.)

_a._ Therasia.

_b._ The northern entrance, 1068 feet deep.

_c._ Thera.

_d._ Mount St. Elias, rising 1887 feet above the sea.

_e._ Aspronisi.

_f._ Little Kaimeni.

_g._ New Kaimeni.

_h._ Old Kaimeni.

_i._ Aphroessa.

_k._ George.]

The neighborhood of Santorin in the Grecian Archipelago has been noted

from very remote times as the theatre of submarine eruptions. This

island, which is itself to all appearance the crater of a vast volcano,

has the form of a crescent, and, with the aid of two smaller islands

which stretch across between the horns of the crescent, encloses an

almost circular bay. We learn from Pliny that in the year 186 before

Christ, within this bay an island rose up which was called Hiera or

the Sacred island. It was twice enlarged during the Christian era, once

in 726, and again in 1427, and still exists under the name of Palaia

Kaimeni, that is to say, the Old Burnt Island. In 1573 a second island

made its appearance, and received the name of the Little Burnt Island,

Mikra Kaimeni. In 1707 and 1709, a third island was thrown up, and was

distinguished from the other two as Nea Kaimeni, the New Burnt Island.

Lastly, in 1866 the hidden volcanic power again became active, and

two new vents were formed, called respectively Aphroessa and George.

“At the end of January,” writes Sir Charles Lyell, “the sea had been

observed in a state of ebullition off the southwest coast, and part

of the Channel between New and Old Kaimeni, marked seventy fathoms

in the Admiralty chart, had become, on February the eleventh, only

twelve fathoms deep. According to M. Julius Schmidt, a gradual rising

of the bottom went on until a small island made its appearance called

afterward Aphroessa. It seems to have consisted of lava pressed upward

and outward almost imperceptibly by steam, which was escaping at every

pore through the hissing scoriaceous crust. ‘It could be seen,’ says

Commander Lindesay Brine, R. N., ‘through the fissures in the cone

that the rocks within were red hot, but it was not till later that an

eruption began.’ On February the eleventh the village of Vulcano on the

southeast coast, where there had been a partial sinking of the ground,

was in great part overwhelmed by the materials cast out from a new vent

which opened in that neighborhood, and to which the name of George was

given, which finally, according to Schmidt, became about two hundred

feet high.

“Commander Brine having ascended on February the twenty-eighth, 1866,

to the top of the crater of Nea Kaimeni, about three hundred and fifty

feet high, looked down upon the new vent then in full activity. The

whole of the cone was swaying with an undulating motion to the right

and left, and appeared sometimes to swell to nearly double its size and

height, to throw out ridges like mountain spurs, till at last a broad

chasm appeared across the top of the cone, accompanied by a tremendous

roar of steam and the shooting up from the new crater, to the height of

from fifty to a hundred feet, of tons of rock and ash mixed with smoke

and steam. Some of these which fell on Mikra Kaimeni, at a distance of

six hundred yards from the crater, measured thirty cubic feet. This

effort over, the ridges slowly subsided, the cone lowered and closed

in, and then, after a few minutes of comparative silence, the struggle

would begin again with precisely similar sounds, action, and result.

Threads of vapor escaping from the old crater of Nea Kaimeni proved

that there was a subterranean connection between the new and the old

vents. Aphroessa, of which the cone was at length raised to a height

of more than sixty feet, was united in August with the main island.

This was due in part at least to the upheaval of the bottom of the sea,

which is now only seven fathoms deep in the channel dividing the New

and Old Kaimenis, whereas in the Admiralty chart the soundings gave a

hundred fathoms.”[97]

[Illustration]

_CHAPTER XVI._

SUBTERRANEAN HEAT--ITS POWERS ILLUSTRATED BY EARTHQUAKES.

_Earthquakes and volcanos proceed from the same common

cause--Recent earthquakes in New Zealand--Vast tracts of

land permanently upraised--Earthquakes of Chili in the

present century--Crust of the Earth elevated--Earthquake of

Cutch in India, 1819--Remarkable instance of subsidence and

upheaval--Earthquake of Calabria, 1783--Earthquake of Lisbon,

1755--Great destruction of life and property--Earthquake

of Peru, August, 1868--General scene of ruin and

devastation--Great sea wave--A ship with all her crew carried a

quarter of a mile inland--Frequency of earthquakes._

The chief effect of volcanic eruptions on the Geological structure of

our Globe consists in the accumulation of cinders and molten rock,

either upon the Surface of the Earth, or in the crevices and caverns

that abound within its solid Crust. Sometimes, indeed, the operations

of an active Volcano are accompanied by a movement of upheaval or

of subsidence. Thus for instance, we have seen that a portion of

the Italian coast was elevated when Monte Nuovo was thrown up, that

the town of Tomboro was submerged on the occasion of the eruption

of Sumbawa, and that the bottom of the sea was notably upheaved by

the last outbreak of the volcanic fires of Santorini. Nevertheless

it appears to be generally the case that when the Crust of the

Earth is once burst open, and a means of escape thus afforded to

the fiery agent below,--in other words, when the active volcano is

established,--the process of upheaval gives place to that of eruption.

But when, as is often the case, no such safety-valve is offered to the

surplus energies of the subterranean fires, then the giant power of

heat, in its struggle to escape, shakes the foundation of the hills,

and uplifts the superincumbent mass of solid rocks.

This theory which ascribes the phenomena of Earthquakes and Volcanos

to the same common cause, acting under different circumstances, is

now almost universally adopted by Geologists; and it may be briefly

enforced by the following considerations. First, though Earthquakes

have sometimes occurred far away from any known volcanic region,

yet they are more frequent in the neighborhood of active or extinct

Volcanos. Secondly, almost all volcanic eruptions are preceded by

Earthquakes; and the Earthquakes generally cease, or, at least become

less violent, when the subterranean fire breaks out in the form of a

Volcano. And, Thirdly, it is plain that the condensed steam which is

generated by internal heat, and the expansive power of the heat itself,

must, of necessity, when pent up in the caverns of the Earth, tend to

produce those very phenomena by which Earthquakes are distinguished.

Let it be observed, however, that while we explain the phenomena in

question by the agency of subterranean heat, this doctrine is by no

means necessary for the main purpose of our present argument. Whatever

may be the cause from which the Earthquake shock proceeds, it is

enough for us to show that the Crust of the Earth has been from time

to time upraised, and dislocated, and rent asunder in modern times,

just as it is supposed in Geological theory, to have been upraised, and

dislocated, and rent asunder from time to time in by-gone ages. We will

set down a few out of the many examples observed and recorded during

the last hundred and twenty years.

When the English colonists settled in New Zealand, about fifty years

ago, they were told by the natives that they might expect a great

Earthquake every seven years. This alarming prediction has not been

literally fulfilled; but it is fully admitted that the total number of

such disturbances within the last half century has not fallen short of

what it should have been according to the above estimate. During the

years 1826 and 1827 several shocks were felt in the neighborhood of

Cook Strait, after which it was observed that the sea-shore had been

uplifted on the north side of Dusky Bay. So transformed was the outline

of the coast that its former features could no longer be recognized;

and a small cove called the Jail, which had previously afforded a

commodious harbor to vessels, engaged in seal fishing, was completely

dried up.

But the most memorable convulsion took place on the night of January

the twenty-third, 1855. A tract of land, about as large as Yorkshire,

on the southwest coast of the North Island, was permanently upraised

from one to nine feet. The harbor of Port Nicholson, together with

the valley of the Hutt, was elevated four to five feet; and a sunken

rock, regarded before as dangerous to navigators, has remained since

the Earthquake three feet above the level of the water. The shock was

felt by ships at sea a hundred and fifty miles from the coast; and it

is estimated that the whole area affected was not less than three times

the extent of the British Islands.

The whole coast of Chili has been subject to great disturbances and

changes of level during the present century. In November, 1837, the

town of Valdivia was destroyed by an Earthquake, and at the same

moment, a whaling vessel, a short distance out at sea, was violently

shaken, and lost her masts. The bottom of the sea was afterward

found to have been raised in some places more than eight feet; and

several rocks appeared high above the water which had previously

been covered at all times by the sea. Two years before, in 1835, the

town of Conception and several others were reduced to ruins by a like

visitation. After the first great convulsion the Earth remained for

many days in a state of commotion. More than three hundred lesser

shocks were counted from the twentieth of February to the fourth of

March. On this occasion, too, the bed of the sea was upheaved; and the

whole island of Santa Maria, seven miles in length, was lifted up from

eight to ten feet above its former level.

The Earthquake of 1822 was more violent, perhaps, and more striking in

its effects, than either of those just mentioned. On the nineteenth of

November in that year a sudden convulsive shock was simultaneously felt

over a space 1200 miles in length. At Valparaiso, and on either side

for a considerable distance, the coast was permanently upheaved. When

Mrs. Graham, who was then living on the spot, and who has left us an

account of the Earthquake, went down to the shore on the following day,

she “found the ancient bed of the sea laid bare and dry, with beds of

oysters, mussels, and other shells adhering to the rocks on which they

grew, the fish being all dead, and exhaling most offensive effluvia.”

Some idea may be formed of the gigantic power here in operation, when

it is remembered that to uplift the coast of Chili, it was necessary

to move the mighty chain of the Andes, and, amongst the rest, the

colossal mass of Aconcagua, 24,000 feet in height. How far this process

of upheaval extended out to sea, beneath the bed of the ocean, has not

been accurately ascertained: but certain it is that, for a considerable

distance, the soundings were found to be shallower than before the

Earthquake. It is roughly estimated that the Crust of the Earth was

elevated over an extent of 100,000 square miles, or about half the area

of France.

On the western coast of India, near the mouth of the river Indus, is

the well-known district of Cutch. In the month of June, 1819, this

extensive territory, not less than half the size of Ireland, was

violently shaken by an Earthquake, several hundred people were killed,

and many towns and villages were laid in ruins. The shocks continued

for some days, and ceased only when the outburst of a Volcano seemed to

open a vent for the troubled spirit within. But what is particularly

worthy of note is that when the Earthquake had passed away, a permanent

change was found to have been effected in the level of the surrounding

country. The town and fort of Sindree, situated on the eastern arm of

the Indus, together with a tract of land 2,000 square miles in extent,

were submerged beneath the waters. The principal buildings, however,

still remained standing, with their upper parts above the surface; and

many of the inhabitants, who had taken refuge in one of the towers

attached to the fort, were saved in boats when the Earthquake had

ceased. On the other hand, within five miles and a half of this very

spot, the level surface of the Earth was upheaved, so as to form a long

elevated bank, fifty miles in length and sixteen in breadth, which

has been called the Ullah Bund, or the Mound of God. Nine years after

this event, Sir Alexander Burnes went out in a boat to the ruins of

Sindree, and standing on the summit of the tower, which still rose two

or three feet above the surface of the water, he could see nothing

around him but a wide expanse of sea, save where a blue streak of land

on the edge of the horizon marked the outline of the Ullah Bund. Here

was a striking illustration, on a small scale, of those changes which

Geologists suppose to have been going on since the world first began;

the dry land had been converted into the bed of the sea, and the level

plain had been elevated into a mountain ridge.

Toward the close of the last century the province of Calabria, in

Southern Italy, was the scene of an Earthquake which offers a very

apposite illustration of our present argument. This celebrated

convulsion is not, however, chiefly remarkable for its violence, or

for its duration, or for the extent of the territory moved. In all

these respects it has been surpassed by many Earthquakes, experienced

in other countries, within the last hundred and fifty years. But the

Calabrian Earthquake has an especial claim on our attention, mainly

from this unusual circumstance, that the region of disturbance was

visited, as Sir Charles Lyell tells us, “both during and after the

convulsions, by men possessing sufficient leisure, zeal, and scientific

information, to enable them to collect and describe with accuracy such

physical facts as throw light on geological questions.”

The shocks were first felt in February, 1783, and continued for nearly

four years. Over a very considerable area of country all the common

landmarks were removed, large tracts of land were forced bodily down

the slopes of mountains; and vineyards, orchards, and cornfields were

transported from one site to another; insomuch that disputes afterward

arose as to who was the rightful owner of the property that had thus

shifted its position. Two farms near Mileto, occupying an extent of

country a mile long and half a mile broad, were actually removed for

a mile down the valley; and “a thatched cottage, together with large

olive and mulberry trees, most of which remained erect, was carried

uninjured to this extraordinary distance.” In other places the surface

of the Earth heaved like the billows of a troubled sea; many houses

were lifted up above the common level, while others subsided below it.

Again and again the solid Crust of the Earth was rent asunder, and

chasms, gorges, ravines, of various depths, were suddenly produced,

in less time than it takes to tell it. Sometimes when the strain was

removed, the yawning gulf as quickly closed again, and then houses,

cattle, and men were swallowed up in the abyss, leaving not a trace

behind. It has even been recorded--strange though it may seem--that

when two shocks rapidly followed one another at the same spot, the

people engulphed by the first, were again cast forth by the second,

being literally disgorged alive from the jaws of death. About 40,000

persons perished in this dreadful visitation, the greater number being

crushed to death beneath the ruins of the towns and villages, others

swallowed up in the yawning fissures as they fled across the open

country, and others again burned in the conflagrations which almost

always followed the shocks of Earthquake.

Everyone has heard of the famous Earthquake of Lisbon. It is chiefly

memorable for the extreme suddenness of the shock, for the immense

extent of the area affected, and for the amount of havoc and

destruction done. On the morning of the fatal day--it was the first

of November, 1755--the sun rose bright and cheerful over the devoted

city, no symptom of impending danger was visible in the sky above or

on the Earth below, and the gay-hearted people were pursuing their

accustomed rounds of pleasure or business, when, suddenly, at twenty

minutes before ten o’clock, a sound like thunder was heard underground,

the Earth was violently shaken, and in another moment, the greater part

of the city was lying in ruins. Within the brief space of six minutes,

60,000 people were crushed to death. The mountains in the vicinity

of the town were cleft asunder. The waters of the sea first retired

from the land, and then rolled back in a huge mountain-like wave fifty

feet above the level of the highest tide. A new quay, built entirely

of marble, had offered a temporary place of refuge to the terrified

inhabitants as they fled from the tumbling ruins of the city. Three

thousand people are said to have been collected upon it, when, all

at once, it sunk beneath the waves, and not a fragment of the solid

masonry, not a vestige of its living freight, was ever seen again. The

bottom of the sea where the quay then stood is now a hundred fathoms

deep.

From Lisbon as a centre the shock of this Earthquake radiated over an

area not less than four times the extent of Europe. Like a great wave

it rolled northward, at the rate of twenty miles a minute, upheaving

the Earth as it moved along, to the coasts of the Baltic Sea and the

German Ocean. The waters of Loch Lomond, in Scotland, were violently

disturbed from beneath, and at Kinsale, in Ireland, the sea rushed

impetuously into the harbor without a breath of wind, and mounting over

the quay, flooded the market-place. Eastward the convulsion was felt as

far as the Alps, and westward it extended to the West India Islands,

and even to the great lakes of Canada. On the north coast of Africa the

disturbance was as violent as in Spain and Portugal; and it is recorded

that at a distance of eight leagues from Morocco, the earth opened and

swallowed up a considerable town with its inhabitants, to the number of

eight or ten thousand people.

Even on the high seas the shock was felt no less distinctly than on

dry land. “Off St. Lucar,” says Sir Charles Lyell, “the captain of the

ship Nancy felt his vessel so violently shaken, that he thought she

had struck the ground, but, on heaving the lead, found a great depth

of water. Captain Clark, from Denia, in latitude 36° 24´ N., between

nine and ten in the morning, had his ship shaken and strained as if she

had struck upon a rock, so that the seams of the deck opened, and the

compass was overturned in the binnacle. Another ship, forty leagues

west of St. Vincent, experienced so violent a concussion, that the men

were thrown a foot and a half perpendicularly up from the deck.” It

is worthy of note that this, the most destructive Earthquake recorded

in history, was not attended with any volcanic eruption; which goes

to confirm our theory that the active Volcano serves as a kind of

safety-valve for the escape of the struggling powers confined within

the Crust of the Earth.[98]

We must not bring our notice of Earthquakes to an end without at least

some brief account of one which has startled the world even since we

began to put together the materials of this Volume. On the Western

Coast of South America there is a long, narrow strip of land, lying

between the lofty crests of the Andes and the shores of the Pacific

Ocean, which from the earliest times has been the familiar home of

Earthquakes. Toward evening on the thirteenth of August, 1868, this

fated region was the scene of a convulsion the most appalling and

destructive that has been recorded within the present century. The

disturbance was felt in its extreme violence for a distance of 1500

miles along the coast; from Ibarra one degree north of the Equator

to Iquique more than twenty degrees south. In ten minutes from the

first shock, 20,000 people perished, and a vast amount of property,

roughly estimated at sixty millions sterling, was utterly destroyed.

Many thriving towns--Iquique, Mexillones, Pisagua, Arica, Ylo, Chala,

and others--were levelled to the ground. Even the very ruins were not

spared. The sea rushed in when the Earthquake shock had ceased, and

carried everything before it in one universal wreck: so that in some

cases not a vestige remained behind to tell the dismayed survivors

where their homesteads once had stood. It might be fancied perhaps

that the cities seated aloft in the security of the Eternal Hills were

beyond the reach of the convulsion that shook the plain below. But no:

Arequipa, far up on the slopes of the western Cordillera, and Pasco,

the highest city in the world, situated on a level with the snowy

summit of the Jungfrau, were shattered into fragments with the same

violence as the cities of the coast.

The various incidents recorded by the survivors are full of fearful

interest. At Iquique, according to one account, about five o’clock in

the evening of the thirteenth of August, a rumbling noise was heard,

then the earth shook violently for some minutes, then the sea, with

a great moan, retired from the shore, and rearing itself up into a

tremendous wave, rushed back upon the land and swept away the town.

“I saw,” says one writer, “the whole surface of the sea rise as if a

mountain side, actually standing up. Another shock, accompanied with

a fearful roar, now took place. I called to my companions to run for

their lives on to the Pampa. Too late! With a horrid crash the sea was

on us, and at one sweep--one terrible sweep--dashed what was Iquique on

to the Pampa. I lost my companions, and in an instant was fighting with

the dark water. The mighty wave surged and roared and leaped. The cries

of human beings and animals were dreadful. A mass of wreck covered me

and kept me down, and I was fast drowning when the sea threw me on to

a beam, but a nail piercing my coat, the timber rolled me again under,

and I lost all sense. I suppose, as in all such cases, I must have

struggled after sensation had left me, for when returning consciousness

came I was grasping under one arm a large plank. Looking round, all was

wreck and desolation. In a moment I was by a returning wave swept into

the bay, and meeting a mass of broken timber, I was struck a fearful

blow on the chin, and the broken end of the plank passed through my

thigh. I knew no more until I found myself on the Pampa, and all dark

around me. I was without trousers, coat, shoes, or hat. Trying to

collect myself, I thought of another wave, and crawled away to the

mountain side, scooped a hole in the ground, and got in; here, wet and

shivering, I spent the night. My wound bled freely. In the morning

I looked out and found Iquique gone, all but a few houses round the

church.”

A good deal of shipping was lying in the bay of Arica. When the waters

first receded the vessels were all carried out to sea, chains, cables,

and anchors snapping asunder like packthread. A moment, afterward they

were borne back irresistibly by the returning wave, and dashed to

pieces on the coast. One more fortunate than the rest, the Wateree, a

vessel of war belonging to the United States Government, was caught up

on the crest of the wave, and with the loss of only one man, was landed

high and dry among the sand-hills a quarter of a mile from the shore.

Before the Earthquake, Arequipa was a prosperous town of 30,000

inhabitants. It enjoyed a considerable trade, and, in importance as

well as size, it was regarded as the third city of Peru, being inferior

only to Lima and Cuzco. The houses were constructed with especial

regard to security against the shock of Earthquakes. They were but

one story high, built of solid stone, and massive to an extraordinary

degree. But these precautions, though the fruit of long experience,

were all of no avail. At Sunset on the fatal thirteenth of August the

populous and thriving city of Arequipa was little better than a heap of

ruins. “Not a church is left standing,” writes an eye-witness, “not a

house habitable. The shock commenced at twenty minutes past five in the

afternoon, and lasted six or seven minutes. The houses being solidly

built and of one story, resisted for one minute, which gave the people

time to rush into the middle of the streets, so that the mortality,

although considerable, is not so great as might have been expected. If

the Earthquake had occurred at night, few indeed would have been left

to tell the story. As it is, the prisoners in the public prison, and

the sick in the hospital, have perished. The Earthquake commenced with

an undulating movement, and as the shock culminated, no one could keep

his feet: the houses rocked as a ship in the trough of the sea, and

came crumbling down. The shrieks of the women, the crash of falling

masonry, the upheaving of the earth, and the clouds of blinding dust,

made up a scene that cannot be described. We had nineteen minor shocks

the same night, and the earth still continues in motion. Nothing has as

yet been done toward disinterring the dead; but I do not think any are

buried alive, as certain death must have been the fate of all those who

were not able to get into the street. The earth has opened in all the

plains around, and water has appeared in various places.”[99]

These are a few typical examples of the more violent convulsions by

which the Crust of the Earth has been disturbed within little more

than a century; and they leave no doubt as to the kind of changes

which may fairly be ascribed to similar agency in the past history of

the Globe. Nor must it be supposed that, because our examples are few

in number, the Earthquake is itself a rare and exceptional event. On

the contrary, the state of partial disturbance and convulsion would

seem to be the natural and ordinary condition of our planet. From the

interesting Catalogue drawn up by Mr. Mallet, it appears that, in our

own times, the number of Earthquakes actually observed and recorded

is, on an average, not less than from two to three every week. Now

this catalogue cannot represent more than one-third of the Globe: for

the disturbances which take place in the profound depths of the ocean

must for the most part escape observation, and many parts even of the

inhabited Earth are still beyond the reach of scientific researches.

It is, therefore, quite a reasonable speculation of Sir Charles

Lyell, that “scarcely a day passes without one or more shocks being

experienced in some part of the Globe.”

Moreover, in Mr. Mallet’s Catalogue no account is taken of those minor

vibrations or tremblings of the Earth’s Crust, which are not attended

by any striking or noteworthy event. And yet such phenomena, when

often repeated, may produce a very important change of level, and

are far more frequent than most persons would be likely to suppose.

In our quiet region of the Globe people are too apt to take for

granted the general stability of the Earth: but in other countries

the inhabitants, warned by long experience, are no less deeply

impressed with a conviction of its instability. Sir John Herschel says

that, in the volcanic regions of Central and Southern America, “the

inhabitants no more think of counting Earthquake shocks, than we do of

counting showers of rain:” nay, he adds that, “in some places along

the coast a shower is a greater variety.” And in Sicily, we are told

they make provision against movements of the Earth’s Crust, just as

we make provision against lightning and storms; so much so that it

is quite a common thing for architects to advertise their houses as

Earth-quake-proof.

[Illustration]

_CHAPTER XVII._

SUBTERRANEAN HEAT--ITS POWERS ILLUSTRATED BY UNDULATIONS OF THE EARTH’S

CRUST.

_Gentle movements of the Earth’s Crust within historic

times--Roman roads and temples submerged in the bay of

Baiæ--Temple of Jupiter Serapis--Singular condition

of its columns--Proof of subsidence and subsequent

upheaval--Indications of a second subsidence now

actually taking place--Gradual upheaval of the coast of

Sweden--Summary of the evidence adduced to establish this

fact--Subsidence of the Earth’s Crust on the west coast of

Greenland--Recapitulation._

SO far we have spoken of the disturbance of the Earth’s Crust in

modern times by sudden and violent convulsions. But there are many

phenomena with which the Geologist is familiar, that cannot be fairly

accounted for unless by supposing that the surface of the Earth was

often elevated and depressed in ancient times, without any sudden

shock, by a slow and almost insensible movement. And, accordingly,

gentle undulations of this kind enter largely into that general theory

of Geology which we have been attempting to draw out and illustrate.

It may be asked, therefore, if we are able to support this part of our

system by examples of similar phenomena occurring within the period

of history. In reply, we shall endeavor to set forth, as briefly as

we can, some of the evidence which has recently come to light on

this subject, and which seems to us not less conclusive than it is

interesting and unexpected.

In the bay of Baiæ, to the west of Naples, two ancient Roman roads may

be distinctly traced, at the present day, for a considerable distance,

permanently submerged beneath the waters. There are, also, in the same

neighborhood, the ruins of the temple of Neptune and of the temple of

the Nymphs, both likewise submerged. “The columns of the former edifice

stand erect in five feet of water, the upper portions just rising

to the surface;[100] the pedestals are supposed to be buried in the

mud below.” Again, on the opposite side of Naples, near Sorrento, “a

road with fragments of Roman buildings, is covered to some depth by

the sea;”[101] and in the island of Capri, at the opening of the bay

of Naples, one of the palaces of Tiberius is also under water. Here,

therefore, it is clear that the Crust of the Earth has subsided over

a very considerable area; since what is now the bed of the sea, was

in the days of the Romans dry land, traversed by roads, and dotted

over with buildings. That the subsidence was slow and gradual may be

inferred, partly from the absence of any record or tradition of a

sudden convulsion producing such a change, and partly, too, from the

unshaken and undisturbed condition of the monuments themselves.

But while this conclusion falls in most happily with our present

argument, it would seem on further examination to bring with it a very

serious difficulty. For, while those ancient monuments testify that

the Crust of the Earth in this locality has _subsided_, the structure

of the sea-coast, interpreted according to Geological principles,

would indicate, on the contrary, that the Crust of the Earth has

been _upheaved_. Close to the sea, at the present day, on the bay of

Baiæ, there is a low, level tract of fertile land, and at a little

distance inland, a lofty range of precipitous cliffs, eighty feet high,

parallel to the line of the coast. This fertile tract, lying between

the sea-beach and the perpendicular cliffs, is about twenty feet

above the sea level, and is composed of regularly stratified deposits

abounding in marine shells of recent species, together with works of

human art, such as tiles, squares of mosaic pavement, fragments of

bricks, and sculptured ornaments. Upon these facts a Geologist would

pronounce without hesitation:--First, that at some period since the

district around Naples was first inhabited by man, the waters of the

sea washed the base of the perpendicular cliffs; secondly, that the

strata in which we now find the recent marine shells, and the remains

of man’s workmanship, were formed during that period by the process

of deposition at the bottom of the sea; and thirdly, that at some

subsequent time, by an upheaval of the Earth’s Crust, these strata were

lifted up so as to form a pretty considerable area of dry land, fit for

agriculture and the arts of life.

Does it not seem, therefore, that we have here a direct contradiction

between the evidence of ancient Roman buildings and the inferences of

modern Geology? Doubtless, they both agree in the main point about

which we are concerned just now, that the Crust of the Earth has

been moved in recent times on the shores of the bay of Naples; but

according to the testimony of the Roman temples, now covered by water,

this movement has been one of _subsidence_, while, according to the

inferences of Geological theory, it has been one of _upheaval_. This

apparent contradiction seems to call for some elucidation.

If we were left in this matter to mere conjecture, we might offer

the following hypothesis as a fair and reasonable solution. We might

suppose that since the days of the Roman Empire, there have been _two

successive movements_ of the Earth’s Crust in the neighborhood of

Naples; first, a movement of subsidence, by which the ancient temples

and roads were submerged to a considerable depth beneath the sea;

afterward, a movement of upheaval, by which the marine strata were

lifted up. If this second movement were exactly equal to the first,

it is plain that the ancient roads and buildings would have been just

restored to their former level. But let us suppose that the amount of

upheaval was something less than the amount of previous subsidence,

and we should have these roads and buildings still submerged, as they

are in point of fact, in a few feet of water. By such an hypothesis,

therefore, the two classes of phenomena might be brought into perfect

harmony.

But we are not obliged to take refuge in hypothesis: for it is now

distinctly proved by a very curious kind of evidence, that the Crust of

the Earth in and about the bay of Baiæ, has been successively depressed

and upraised since the third century of the Christian era; nay more,

that the subsidence in the first case was greater than the subsequent

upheaval. Near Pozzuoli, on the level tract of land which, as we

have said, intervenes between the sea and the lofty range of inland

cliffs, are to be seen at the present day the ruins of a splendid

Roman edifice, usually called the temple of Jupiter Serapis, though,

according to some writers, it was not a temple at all, but a public

establishment for baths. These ruins first attracted attention about

the middle of the last century. Three magnificent marble columns were

still standing erect, with their lower parts buried in the stratified

deposits already described, and their upper portions, which projected

above the surface of the land, partly concealed by bushes. When the

soil was removed the original plan of the building could be distinctly

traced. “It was of a quadrangular form, seventy feet in diameter, and

the roof had been supported by forty-six noble columns, twenty-four

of granite and the rest of marble.” Many of the pillars have been

shattered in the course of time, and lie strewn in fragments on the

pavements. The three which are still standing erect, are upward of

forty feet in height, each carved out of a solid block of marble; and,

what is chiefly to our purpose, they exhibit, curiously inscribed on

their surface, memorials of the physical changes in which they have

borne a part.

The base of these lofty columns is, at present, slightly below the

level of the sea. Their outer surface is smooth for about twelve

feet above the pedestals; then, for the next nine feet the marble is

everywhere bored by a well-known species of mussel, which it is certain

can live only in the sea. Above this band of perforations the pillars

again present a smooth surface, and continue smooth to the top. The

first inference from these facts is, that the columns in question

must have been at one time submerged to a height of twenty-one feet

above the pedestals; otherwise they could not have been bored at that

height by a species of animal that can only exist in sea-water. Since

that time, therefore, the land at this spot must have been upraised

twenty-one feet. Furthermore, the temple of Jupiter was certainly not

built at the bottom of the sea, but upon dry land; therefore, after

the temple had been built, the Crust of the Earth must have subsided

at least twenty-one feet. Once more: as the floor of the temple is now

somewhat below the level of the sea, and as it is not very likely it

was at first so built, we may fairly infer that it is now lower than it

originally stood; and consequently, that the total amount of upheaval

has not been equal to the total amount of subsidence. Though we cannot

fix the exact date at which the subsidence began, it was probably not

earlier than the third century; for in the atrium of the temple is an

inscription recording that it was adorned with precious marbles by the

emperor Septimus Severus.

It cannot be supposed for a moment that these changes were effected

by a rise and fall in the level of the sea rather than by a movement

of the Earth’s Crust. A permanent change in the level of the

Mediterranean, in any given locality, would, of necessity, imply a

change of level over its entire extent; and therefore, if the phenomena

exhibited in the bay of Baiæ arose from such a cause, we should meet

with phenomena of the same kind along the whole length of the Italian

coast. Now, in point of fact, no such changes of level are elsewhere

apparent; and consequently, they must be ascribed in the bay of Baiæ,

not to an upward and downward movement of the sea, but to an upward and

downward movement of the land.

We must not omit to state, before leaving the subject, that it is now

ascertained, by a series of accurate observations, that the Crust

of the Earth in this interesting locality is once again slowly and

gradually subsiding. At the beginning of the century the platform of

the temple stood at about the level of the sea; it is now more than

a foot below it. Nay, this second subsidence appears to have begun

even before the present century. “In the year 1813,” writes a modern

traveller, “I resided for four months in the Capuchin convent of

Pozzuoli, which is situated between the road from Naples and the sea,

at the entrance of the town of Pozzuoli. In the Capuchin convents

the oldest friar is called ‘il molto reverende,’ and the one who

then enjoyed the title in this convent was ninety-three years old.

He informed me that, when he was a young man, the road from Naples

passed on the _seaward side_ of the convent; but that, from the

gradual sinking of the soil, the road was obliged to be altered to

its present course. While I was staying at the convent, the refectory

as well as the entrance gate, were from six inches to a foot under

water whenever strong westerly winds prevailed, so as to cause the

waters of the Mediterranean to rise. Thirty years previously, my old

informant stated, such an occurrence never took place. In fact, it is

not probable that the builder of the convent would have placed the

ground-floor so low as to expose to inundation as it now is.”[102]

On the shores of the Baltic Sea we find another illustration of

our theory upon a more extended scale. About a century and a half

ago the Swedish naturalist, Celsius, expressed a belief that a

remarkable change of level was taking place along the eastern coast

of Scandinavia; and he ascribed the change to a subsidence of the

waters of the Baltic Sea. This opinion was received at first with

no small amount of incredulity; but the arguments of Celsius were

plausible and attractive enough to excite a controversy, and the

controversy once aroused was not easily set at rest. Accordingly,

since his time the facts upon which he relied have been more strictly

examined, difficulties have been started and investigated, many new

facts, at first unknown or unnoticed, have been brought to light, and

the whole question has been rigorously discussed by scientific men.

It would be tedious to go through the history of the discussion, or

to develop at any length the arguments which in the end have proved

successful, involving as they do a multitude of minute observations and

nice measurements, made at a great variety of different places with

hard-sounding names. But the general result may be readily stated and

as readily understood.

It appears that numerous sunken reefs, well known to navigators, have,

within the last two centuries, become visible above water; that many

ancient ports have become inland towns; that many small islands have

become united to one another and to the mainland by grassy plains;

that rocky points which in former times just peeped above the water,

and afforded refuge only to a solitary sea-bird, are now grown into

little islets; and that several of the old fishing grounds are now

deserted for their shallowness, nay, in some cases, altogether dried

up. From these facts the inference is plain; either the solid Crust of

the Earth has been uplifted, or the waters of the sea have subsided.

Now it is certain there has been no subsidence of the sea; for such

a subsidence, as we before observed, if it took place at all, should

have been general; whereas there are many points on the shores of the

Baltic, especially along the coasts of Denmark and Prussia, where it

can be proved that no change of level has taken place for centuries.

And therefore the phenomena above described we must attribute to an

upheaval of the Earth’s Crust.[103]

Such is the kind of reasoning with which this inquiry has been pursued;

and it may now be set down as a received and established fact, that a

slow and gradual process of upheaval is going on, at the present day,

on the shores of the Baltic Sea, at the rate of from two to four feet

in a century; and this is over an area of unknown breadth, and not less

than 1000 miles in length. Evidence of a similar kind has lately been

adduced to prove that the west coast of Greenland is just now gradually

subsiding for a space of more than 600 miles from north to south.

“Ancient buildings on low, rocky islands, and on the shore of the

mainland, have been gradually submerged, and experience has taught the

aboriginal Greenlander never to build his hut near the water’s edge.

In one case the Moravian settlers have been obliged more than once to

move the poles upon which their large boats were set, and the old poles

still remain beneath the water as silent witnesses of the change.”[104]

It should seem, therefore, that the Crust of the Earth is not that

fixed and immovable mass of unyielding rock which it is often supposed

to be. Whatever the gigantic power is which lies shut up within it,

and which seems, clearly enough, to be developed in some way or

another--perhaps in many ways at once--from internal heat, that power

exercises a mighty influence from age to age on the outward form of

our planet. Like the wind, indeed, it bloweth where it listeth, and

we cannot tell whence it cometh or whither it goeth; but we can hear

the sound thereof, and witness its effects when it breaks out now in

this quarter of the world, and now in that, bursting open the massive

rocks, and furiously vomiting forth whole mountains of smouldering

ashes and molten mineral; or again, when, failing to find a vent, it

shakes the foundations of the hills, and shivers into fragments the

most enduring works of man--castles, temples, palaces,--filling every

heart with terror and dismay; or, in fine, when it gently upheaves the

bottom of the ocean, or by withdrawing the strain, allows the Crust of

the Earth to subside, with a movement so gradual and insensible as to

escape the notice of the multitudes who are toiling in the busy cities

on its Surface. That phenomena of this kind have been going on in all

past ages, is now universally assumed in the speculations of Geology:

that they are going on in the present age, we have here endeavored to

prove by the evidence of facts. If we have succeeded according to our

expectations, the reader will be prepared to admit that, on this point

at least, it is not the Geologist who may fairly be charged with having

recourse to the inventions of his fancy, but rather those who, assuming

as a first principle that Geology is false, perseveringly shut their

eyes to the physical changes that are going on around them.

[Illustration]

PART II.

THE ANTIQUITY OF THE EARTH CONSIDERED IN RELATION TO THE HISTORY OF

GENESIS.

_CHAPTER XVIII._

STATEMENT OF THE QUESTION AND EXPOSITION OF THE AUTHORS VIEW.

_The general principles of geological theory accepted by the

author--These principles plainly import the extreme antiquity

of the earth--Illustration from the coal, the chalk, and the

boulder clay--This conclusion not at variance with the inspired

history of creation--Chronology of the Bible--Genealogies of

Genesis--Date of the creation not fixed by Moses--Progress of

opinion on this point--Cardinal Wiseman, Father Perrone, Father

Pianciani--Doctor Buckland--Doctor Chalmers, Doctor Pye Smith,

Hugh Miller--Author’s view explained--Charge of rashness and

irreverence answered--Admonitions of Saint Augustine and Saint

Thomas._

The reader has now before him a general outline of Geological theory,

together with some familiar illustrations of the evidence by which it

is supported. We shall not attempt to enforce this evidence by any

remarks of our own. Indeed it is of a kind that can derive but little

aid from the arts of logic or rhetoric. It needs but to be fairly

understood, and if it does not altogether compel our assent, it begets

at least a presumption so strong as to leave little room for doubt or

hesitation.

Nobody, so far as we know, has ever hesitated to believe that the

Round Towers of Ireland are the work of human hands. And yet if some

incredulous skeptic were to raise the cry against this common opinion,

were to argue that it is a mere hypothesis, and call for proof, we

should be embarrassed how to answer him. We could only say that these

monuments have all the characteristic marks of man’s handiwork;

and that buildings of this kind have never been known to come into

existence except through the agency of Man. But should our vexatious

skeptic contend that they were possibly produced by a freak of Nature;

or that they were built in the beginning by the Creator of the World,

who certainly might have made them had He been so minded, we should

think him very unreasonable, and probably not feel much disposed to

prolong the discussion. In like manner the theory of Geology which we

are defending, cannot be established by a rigid demonstration; but we

believe there is not one man of sense and judgment, who, being fully

master of the evidence on which it rests, hesitates to accept that

theory, at least in its more general outlines. No doubt many able and

eminent men are to be found arrayed against Geology; but it would

be easy to show from their writings that they have never thoroughly

examined the facts about which they talk so flippantly, and which they

often set aside so lightly.

Geology and Revelation or, the Ancient History of the Earth, considered in the geological facts and revealed religion. · 第 20 / 22 章

With this sketch of Geological Chronology before us, we can now more