Summarizing--it appears from the preceding facts that it is

possible to produce at will, purulent infections with no elements

of putrescence, putrescent purulent infections, anthracoid

purulent infections, and finally combinations of these types of

lesions varying according to the proportions of the mixtures of

the specific organisms made to act on the living tissues.

These are the principal facts I have to communicate to the

Academy in my name and in the names of my collaborators, Messrs.

Joubert and Chamberland. Some weeks ago (Session of the 11th of

March last) a member of the Section of Medicine and Surgery, M.

Sedillot, after long meditation on the lessons of a brilliant

career, did not hesitate to assert that the successes as well as

the failures of Surgery find a rational explanation in the

principles upon which the germ theory is based, and that this

theory would found a new Surgery--already begun by a celebrated

English surgeon, Dr. Lister, [Footnote: See Lord Lister's paper

in the present volume.--Ed.] who was among the first to

understand its fertility. With no professional authority, but

with the conviction of a trained experimenter, I venture here to

repeat the words of an eminent confrere.

ON THE EXTENSION OF THE GERM THEORY

TO THE ETIOLOGY OF CERTAIN COMMON DISEASES

[Footnote: Read before the French Academy of Sciences, May 3,

1880. Published in Comptes rendus, de l'Academie des Sciences,

xc., pp. 1033-44.]

When I began the studies now occupying my attention, [Footnote:

In 1880. Especially engaged in the study of chicken cholera and

the attenuation of virulence--Translator.] I was attempting to

extend the germ theory to certain common diseases. I do not know

when I can return to that work. Therefore in my desire to see it

carried on by others, I take the liberty of presenting it to the

public in its present condition.

I. Furuncles. In May, 1879, one of the workers in my laboratory

had a number of furuncles, appearing at short intervals,

sometimes on one part of the body and sometimes on another.

Constantly impressed with the thought of the immense part played

by microscopic organisms in Nature, I queried whether the pus in

the furuncles might not contain one of these organisms whose

presence, development, and chance transportation here and there

in the tissues after entrance would produce a local inflammation,

and pus formation, and might explain the recurrence of the

illness during a longer or shorter time. It was easy enough to

subject this thought to the test of experiment.

First observation.--On June second, a puncture was made at the

base of the small cone of pus at the apex of a furuncle on the

nape of the neck. The fluid obtained was at once sowed in the

presence of pure air--of course with the precautions necessary to

exclude any foreign germs, either at the moment of puncture, at

the moment of sowing in the culture fluid, or during the stay in

the oven, which was kept at the constant temperature of about 35

degrees C, The next day, the culture fluid had become cloudy and

contained a single organism, consisting of small spherical points

arranged in pairs, sometimes in fours, but often in irregular

masses. Two fluids were preferred in these experiments--chicken

and yeast bouillon. According as one or the other was used,

appearances varied a little. These should be described. With the

yeast water, the pairs of minute granules are distributed

throughout the liquid, which is uniformly clouded. But with the

chicken bouillon, the granules are collected in little masses

which line the walls and bottom of the flasks while the body of

the fluid remains clear, unless it be shaken: in this case it

becomes uniformly clouded by the breaking up of the small masses

from the walls of the flasks.

Second observation.--On the tenth of June a new furuncle made its

appearance on the right thigh of the same person. Pus could not

yet be seen under the skin, but this was already thickened and

red over a surface the size of a franc. The inflamed part was

washed with alcohol, and dried with blotting paper passed through

the flame of an alcohol lamp. A puncture at the thickened portion

enabled us to secure a small amount of lymph mixed with blood,

which was sowed at the same time as some blood taken from the

finger of the hand. The following days, the blood from the finger

remained absolutely sterile: but that obtained from the center of

the forming furuncle gave an abundant growth of the same small

organism as before.

Third observation.--The fourteenth of June, a new furuncle

appeared on the neck of the same person. The same examination,

the same result, that is to say the development of the

microscopic organism previously described and complete sterility

of the blood of the general circulation, taken this time at the

base of the furuncle outside of the inflamed area.

At the time of making these observations I spoke of them to Dr.

Maurice Reynaud, who was good enough to send me a patient who had

had furuncles for more than three months. On June thirteenth I

made cultures of the pus from a furuncle of this man. The next

day there was a general cloudiness of the culture fluids,

consisting entirely of the preceding parasite, and of this alone.

Fourth observation.--June fourteenth, the same individual showed

me a newly forming furuncle in the left axilla: there was wide-

spread thickening and redness of the skin, but no pus was yet

apparent. An incision at the center of the thickening showed a

small quantity of pus mixed with blood. Sowing, rapid growth for

twenty-four hours and the appearance of the same organism. Blood

from the arm at a distance from the furuncle remained completely

sterile.

June 17, the examination of a fresh furuncle on the same

individual gave the same result, the development of a pure

culture of the same organism.

Fifth observation.--July twenty-first, Dr. Maurice Reynaud

informed me that there was a woman at the Lariboisiere hospital

with multiple furuncles. As a matter of fact her back was covered

with them, some in active suppuration, others in the ulcerating

stage. I took pus from all of these furuncles that had not

opened. After a few hours, this pus gave an abundant growth in

cultures. The same organism, without admixture, was found. Blood

from the inflamed base of the furuncle remained sterile.

In brief, it appears certain that every furuncle contains an

aerobic microscopic parasite, to which is due the local

inflammation and the pus formation that follows.

Culture fluids containing the minute organism inoculated under

the skin of rabbits and guinea-pigs produce abscesses generally

small in size and that promptly heal. As long as healing is not

complete the pus of the abscesses contains the microscopic

organism which produced them. It is therefore living and

developing, but its propagation at a distance does not occur.

These cultures of which I speak, when injected in small

quantities in the jugular vein of guinea pigs show that the

minute organism does not grow in the blood. The day after the

injection they cannot be recovered even in cultures. I seem to

have observed as a general principle, that, provided the blood

corpuscles are in good physiological condition it is difficult

for aerobic parasites to develop in the blood. I have always

thought that this is to be explained by a kind of struggle

between the affinity of the blood corpuscles for oxygen and that

belonging to the parasite in cultures. Whilst the blood

corpuscles carry off, that is, take possession of all the oxygen,

the life and development of the parasite become extremely

difficult or impossible. It is therefore easily eliminated,

digested, if one may use the phrase. I have seen these facts many

times in anthrax and chicken-cholera, diseases both of which are

due to the presence of an aerobic parasite.

Blood cultures from the general circulation being always sterile

in these experiments, it would seem that under the conditions of

the furuncular diathesis, the minute parasite does not exist in

the blood. That it cannot be cultivated for the reason given, and

that it is not abundant is evident; but, from the sterility of

the cultures reported (five only) it should not be definitely

concluded that the little parasite may not, at some time, be

taken up by the blood and transplanted from a furuncle when it is

developing to another part of the body, where it may be

accidentally lodged, may develop and produce a new furuncle. I am

convinced that if, in cases of furuncular diathesis, not merely a

few drops but several grams of blood from the general circulation

could be placed under cultivation frequent successful growths

would be obtained. [Footnote: This prediction is fully carried

out in the present day successful use of considerable amounts of

blood in cultures and the resultant frequent demonstrations of

bacteria present in the circulation in many infections.--

Translator.] In the many experiments I have made on the blood in

chicken-cholera, I have frequently demonstrated that repeated

cultures from droplets of blood do not show an even development

even where taken from the same organ, the heart for example, and

at the moment when the parasite begins its existence in the

blood, which can easily be understood. Once even, it happened

that only three out of ten chickens died after inoculation with

infectious blood in which the parasite had just began to appear,

the remaining seven showed no symptoms whatever. In fact, the

microbe, at the moment of beginning its entrance into the blood

may exist singly or in minute numbers in one droplet and not at

all in its immediate neighbor. I believe therefore that it would

be extremely instructive in furunculosis, to find a patient

willing to submit to a number of punctures in different parts of

the body away from formed or forming furuncles, and thus secure

many cultures, simultaneous of otherwise, of the blood of the

general circulation. I am convinced that among them would be

found growths of the micro-organism of furuncles.

II. On Osteomyelitis. Single observation. I have but one

observation relating to this severe disease, and in this Dr.

Lannelongue took the initiative. The monograph on osteomyelitis

published by this learned practitioner is well known, with his

suggestion of the possibility of a cure by trephining the bone

and the use of antiseptic washes and dressings. On the fourteenth

of February, at the request of Dr. Lannelongue I went to the

Sainte-Eugenie hospital, where this skillful surgeon was to

operate on a little girl of about twelve years of age. The right

knee was much swollen, as well as the whole leg below the calf

and a part of the thigh above the knee. There was no external

opening. Under chloroform, Dr. Lannelongue made a long incision

below the knee which let out a large amount of pus; the tibia was

found denuded for a long distance. Three places in the bone were

trephined. From each of these, quantities of pus flowed. Pus from

inside and outside the bone was collected with all possible

precautions and was carefully examined and cultivated later. The

direct microscopic study of the pus, both internal and external,

was of extreme interest. It was seen that both contained large

numbers of the organism similar to that of furuncles, arranged in

pairs, in fours and in packets, some with sharp clear contour,

others only faintly visible and with very pale outlines. The

external pus contained many pus corpuscles, the internal had none

at all. It was like a fatty paste of the furuncular organism.

Also, it may be noted, that growth of the small organism had

begun in less than six hours after the cultures were started.

Thus I saw, that it corresponded exactly with the organism of

furuncles. The diameter of the individuals was found to be one

one-thousandth of a millimeter. If I ventured to express myself

so I might say that in this case at least the osteomyelitis was

really a furuncle of the bone marrow. [Footnote: This has been

demonstrated, as is well known.--Translator.] It is undoubtedly

easy to induce osteomyelitis artificially in living animals.

III. On puerperal fever.--First observation. On the twelfth of

March, 1878, Dr. Hervieux was good enough to admit me to his

service in the Maternity to visit a woman delivered some days

before and seriously ill with puerperal fever. The lochia were

extremely fetid. I found them full of micro-organisms of many

kinds. A small amount of blood was obtained from a puncture on

the index finger of the left hand, (the finger being first

properly washed and dried with a STERILE towel,) and then sowed

in chicken bouillon. The culture remained sterile during the

following days.

The thirteenth, more blood was taken from a puncture in the

finger and this time growth occurred. As death took place on the

sixteenth of March at six in the morning, it seems that the blood

contained a microscopic parasite at least three days before.

The fifteenth of March, eighteen hours before death, blood from a

needle-prick in the left foot was used. This culture also was

fertile.

The first culture, of March thirteenth, contained only the

organism of furuncles; the next one, that of the fifteenth,

contained an organism resembling that of furunculosis, but which

always differed enough to make it easy usually to distinguish it.

In this way; whilst the parasite of furuncles is arranged in

pairs, very rarely in chains of three or four elements, the new

one, that of the culture of the fifteenth, occurs in long chains,

the number of cells in each being indefinite. The chains are

flexible and often appear as little tangled packets like tangled

strings of pearls.

The autopsy was performed on the seventeenth at two o'clock.

There was a large amount of pus in the peritoneum. It was sowed

with all possible precautions. Blood from the basilic and femoral

veins was also sowed. So also was pus from the mucous surface of

the uterus, from the tubes, and finally that from a lymphatic in

the uterine wall. These are the results of these cultures: in all

there were the long chains of cells just spoken of above, and

nowhere any mixture of other organisms, except in the culture

from the peritoneal pus, which, in addition to the long chains,

also contained the small pyogenic vibrio which I describe under

the name ORGANISM OF PUS in the Note I published with Messrs.

Joubert and Chamberland on the thirtieth of April, 1878.

[Footnote: See preceding paper.]

Interpretation of the disease and of the death.--After

confinement, the pus that always naturally forms in the injured

parts of the uterus instead of remaining pure becomes

contaminated with microscopic organisms from outside, notably the

organism in long chains and the pyogenic vibrio. These organisms

pass into the peritoneal cavity through the tubes or by other

channels, and some of them into the blood, probably by the

lymphatics. The resorption of the pus, always extremely easy and

prompt when it is pure, becomes impossible through the presence

of the parasites, whose entrance must be prevented by all

possible means from the moment of confinement.

Second observation.--The fourteenth of March, a woman died of

puerperal fever at the Lariboisiere hospital; the abdomen was

distended before death.

Pus was found in abundance by a peritoneal puncture and was

sowed; so also was blood from a vein in the arm. The culture of

pus yielded the long chains noted in the preceding observation

and also the small pyogenic vibrio. The culture from the blood

contained only the long chains.

Third observation.--The seventeenth of May, 1879, a woman, three

days past confinement, was ill, as well as the child she was

nursing. The lochia were full of the pyogenic vibrio and of the

organism of furuncles, although there was but a small proportion

of the latter. The milk and the lochia were sowed. The milk gave

the organism in long chains of granules, and the lochia only the

pus organism. The mother died, and there was no autopsy.

On May twenty-eighth, a rabbit was inoculated under the skin of

the abdomen with five drops of the preceding culture of the

pyogenic vibrio. The days following an enormous abscess formed

which opened spontaneously on the fourth of June. An abundantly

cheesy pus came from it. About the abscess there was extensive

induration. On the eighth of June, the opening of the abscess was

larger, the suppuration active. Near its border was another

abscess, evidently joined with the first, for upon pressing it

with the finger, pus flowed freely from the opening in the first

abscess. During the whole of the month of June, the rabbit was

sick and the abscesses suppurated, but less and less. In July

they closed; the animal was well. There could only be felt some

nodules under the skin of the abdomen.

What disturbances might not such an organism carry into the body

of a parturient woman, after passing into the peritoneum, the

lymphatics or the blood through the maternal placenta! Its

presence is much more dangerous than that of the parasite

arranged in chains. Furthermore, its development is always

threatening, because, as said in the work already quoted (April,

1878) this organism can be easily recovered from many ordinary

waters.

I may add that the organism in long chains, and that arranged in

pairs are also extremely widespread, and that one of their

habitats is the mucous surfaces of the genital tract. [Footnote:

When, by the procedure I elsewhere described, urine is removed in

a pure condition by the urethra from the bladder, if any chance

growth occurs through some error of technic, it is the two

organisms of which I have been speaking that are almost

exclusively present.]

Apparently there is no puerperal parasite, properly speaking. I

have not encountered true septicemia in my experiments; but it

ought to be among the puerperal affections.

Fourth observation.--On June fourteenth, at the Lariboisiere, a

woman was very ill following a recent confinement; she was at the

point of death; in fact she did die on the fourteenth at

midnight. Some hours before death pus was taken from an abscess

on the arm, and blood from a puncture in a finger. Both were

sowed. On the next day (the fifteenth) the flask containing the

pus from the abscess was filled with long chains of granules. The

flask containing the blood was sterile. The autopsy was at ten

o'clock on the morning of the sixteenth. Blood from a vein of the

arm, pus from the uterine walls and that from a collection in the

synovial sac of the knee were all placed in culture media. All

showed growth, even the blood, and they all contained the long

strings of granules. The peritoneum contained no pus.

Interpretation of the disease and of the death.--The injury of

the uterus during confinement as usual furnished pus, which gave

a lodging place for the germs of the long chains of granules.

These, probably through the lymphatics, passed to the joints and

to some other places, thus being the origin of the metastic

abscesses which produced death.

Fifth observation.--On June seventeenth, M. Doleris, a well-known

hospital interne, brought to me some blood, removed with the

necessary precautions, from a child dead immediately after birth,

whose mother, before confinement had had febrile symptoms with

chills. This blood, upon cultivation, gave an abundance of the

pyogenic vibrio. On the other hand, blood taken from the mother

on the morning of the eighteenth (she had died at one o'clock

that morning) showed no development whatever, on the nineteenth

nor on following days. The autopsy on the mother took place on

the nineteenth. It is certainly worthy of note that the uterus,

peritoneum and intestines showed nothing special, but the liver

was full of metastatic abscesses. At the exit of the hepatic vein

from the liver there was pus, and its walls were ulcerated at

this place. The pus from the liver abscesses was filled with the

pyogenic vibrio. Even the liver tissues, at a distance from the

visible abscesses, gave abundant cultures of the same organism.

Interpretation of the disease and of the death.--The pyogenic

vibrio, found in the uterus, or which was perhaps already in the

body of the mother, since she suffered from chills before

confinement, produced metastatic abscesses in the liver and,

carried to the blood of the child, there induced one of the forms

of infection called purulent, which caused its death.

Sixth observation.--The eighteenth of June, 1879, M. Doleris

informed me that a woman confined some days before at the Cochin

Hospital, was very ill. On the twentieth of June, blood from a

needle-prick in the finger was sowed; the culture was sterile. On

July fifteenth, that is to say twenty-five days later, the blood

was tried again. Still no growth. There was no organism

distinctly recognizable in the lochia: the woman was

nevertheless, they told me, dangerously ill and at the point of

death. As a matter of fact, she did die on the eighteenth of July

at nine in the morning: as may be seen, after a very long

illness, for the first observations were made over a month

before: the illness was also very painful, for the patient could

make no movement without intense suffering.

An autopsy was made on the nineteenth at ten in the morning, and

was of great interest. There was purulent pleurisy with a

considerable pocket of pus, and purulent false membranes on the

walls of the pleura. The liver was bleached, fatty, but of firm

consistency, and with no apparent metastatic abscesses. The

uterus, of small size, appeared healthy; but on the external

surface whitish nodules filled with pus were found. THERE WAS

NOTHING IN THE PERITONEUM, WHICH WAS NOT INFLAMED; but there was

much pus in the shoulder joints and the symphysis pubis.

The pus from the abscesses, upon cultivation, gave the long

chains of granules--not only that of the pleura, but that from

the shoulders and a lymphatic of the uterus as well. An

interesting thing, but easily understood, was that the blood from

a vein in the arm and taken three-quarters of an hour after death

was entirely sterile. Nothing grew from the Fallopian tubes nor

the broad ligaments.

Interpretation of the disease and of the death.--The pus found in

the uterus after confinement became infected with germs of

microscopic organisms which grew there, then passed into the

uterine lymphatics, and from there went on to produce pus in the

pleura and in the articulations.

Seventh observation.--On June eighteenth, M. Doleris informed me

that a woman had been confined at the Cochin Hospital five days

before and that fears were entertained as to the results of an

operation that had been performed, it having been necessary to do

an embryotomy. The lochia were sowed on the 18th; there was not

the slightest trace of growth the next day nor the day after.

Without the least knowledge of this woman since the eighteenth,

on the twentieth I ventured to assert that she would get well. I

sent to inquire about her. This is the text of the report: "THE

WOMAN IS DOING EXTREMELY WELL; SHE GOES OUT TOMORROW"

Interpretation of the facts.--The pus naturally formed on the

surface of the injured parts did not become contaminated with

organisms brought from without. Natura medicatrix carried it off,

that is to say the vitality of the mucous surfaces prevented the

development of foreign germs. The pus was easily resorbed, and

recovery took place.

I beg the Academy to permit me, in closing, to submit certain

definite views, which I am strongly inclined to consider as

legitimate conclusions from the facts I have had the honor to

communicate to it.

Under the expression PUERPERAL FEVER are grouped very different

diseases, [Footnote: Interesting as the starting point of the

conception of diseases according to the etiological factor, not

by groups of symptoms.--Translator.] but all appearing to be the

result of the growth of common organisms which by their presence

infect the pus naturally formed on injured surfaces, which spread

by one means or another, by the blood or the lymphatics, to one

or another part of the body, and there induce morbid changes

varying with the condition of the parts, the nature of the

parasite, and the general constitution of the subject.

Whatever this constitution, does it not seem that by taking

measures opposing the production of these common parasitic

organisms recovery would usually occur, except perhaps when the

body contains, before confinement, microscopic organisms, in

contaminated internal or external abscesses, as was seen in one

striking example (fifth observation). The antiseptic method I

believe likely to be sovereign in the vast majority of cases. It

seems to me that IMMEDIATELY AFTER CONFINEMENT the application of

antiseptics should be begun. Carbolic acid can render great

service, but there is another antiseptic, the use of which I am

strongly inclined to advise, this is boric acid in concentrated

solution, that is, four per cent. at the ordinary temperature.

This acid, whose singular influence on cell life has been shown

by M. Dumas, is so slightly acid that it is alkaline to certain

test papers, as was long ago shown by M. Chevreul, besides this

it has no odor like carbolic acid, which odor often disturbs the

sick. Lastly, its lack of hurtful effects on mucous membranes,

notably of the bladder, has been and is daily demonstrated in the

hospitals of Paris. The following is the occasion upon which it

was first used. The Academy may remember that I stated before it,

and the fact has never been denied, that ammoniacal urine is

always produced by a microscopic organism, entirely similar in

many respects to the organism of furuncles. Later, in a joint

investigation with M. Joubert, we found that a solution of boric

acid was easily fatal to these organisms. After that, in 1877, I

induced Dr. Guyon, in charge of the genito-urinary clinic at the

Necker hospital, to try injections of a solution of boric acid in

affections of the bladder. I am informed by this skilful

practitioner that he has done so, and daily observes good results

from it. He also tells me that he performs no operation of

lithotrity without the use of similar injections. I recall these

facts to show that a solution of boric acid is entirely harmless

to an extremely delicate mucous membrane, that of the bladder,

and that it is possible to fill the bladder with a warm solution

of boric acid without even inconvenience.

To return to the confinement cases. Would it not be of great

service to place a warm concentrated solution of boric acid, and

compresses, at the bedside of each patient; which she could renew

frequently after saturating with the solution, and this also

after confinement. It would also be acting the part of prudence

to place the compresses, before using, in a hot air oven at 150

degrees C., more than enough to kill the germs of the common

organisms. [Footnote: The adoption of precautions, similar to

those here suggested, has resulted in the practically complete

disappearance of puerperal fevor.--Translator.]

Was I justified in calling this communication "ON THE EXTENSION

OF THE GERM THEORY TO THE ETIOLOGY OF CERTAIN COMMON DISEASES?" I

have detailed the facts as they have appeared to me and I have

mentioned interpretations of them: but I do not conceal from

myself that, in medical territory, it is difficult to support

one's self wholly on subjective foundations. I do not forget that

Medicine and Veterinary practice are foreign to me. I desire

judgment and criticism upon all my contributions. Little tolerant

of frivolous or prejudiced contradiction, contemptuous of that

ignorant criticism which doubts on principle, I welcome with open

arms the militant attack which has a method in doubting and whose

rule of conduct has the motto "More light."

It is a pleasure once more to acknowledge the helpfulness of the

aid given me by Messrs. Chamberland and Roux during the studies I

have just recorded. I wish also to acknowledge the great

assistance of M. Doleris.

PREJUDICES WHICH HAVE RETARDED THE PROGRESS OF GEOLOGY

UNIFORMITY IN THE SERIES OF PAST CHANGES IN THE ANIMATE AND

INANIMATE WORLD

BY

SIR CHARLES LYELL

INTRODUCTORY NOTE

Sir Charles Lyell was born near Kirriemuir, Forfarshire,

Scotland, on November 14, 1797. He graduated from Exeter College,

Oxford, in 1819, and proceeded to the study of law. Although he

practised for a short time, he was much hampered in this

profession, as in all his work, by weak eyesight; and after the

age of thirty he devoted himself chiefly to science.

Lyell's father was a botanist of some distinction, and the son

seems to have been interested in natural history from an early

age. While still an undergraduate he made geological journeys in

Scotland and on the Continent of Europe, and throughout his life

he upheld by precept and example the importance of travel for the

geologist.

The first edition of his "Principles of Geology" was published in

1830; and the phrase used in the sub-title, "an attempt to

explain the former changes of the earth's surface, by reference

to causes now in action" strikes the keynote of his whole work.

All his life he continued to urge this method of explanation in

opposition to the hypotheses, formerly much in vogue, which

assumed frequent catastrophes to account for geologic changes.

The chapters here printed give his own final statement of his

views on this important issue.

Lyell's scientific work received wide recognition: he was more

than once President of the Geological Society, in 1864 was

President of the British Association, was knighted in 1848, and

made a baronet in 1864. He possessed a broad general culture, and

his home was a noted center of the intellectual life of London.

He twice came to the United States to lecture, and created great

interest. On his death, on February 22, 1875, he was buried in

Westminster Abbey.

Persistent as were Lyell's efforts for the establishment of his

main theory, he remained remarkably open-minded; and when the

evolutionary hypothesis was put forward he became a warm

supporter of it. Darwin in his autobiography thus sums up Lyell's

achievement: "The science of geology is enormously indebted to

Lyell--more so, as I believe, than to any other man who ewer

lived."

THE PROGRESS OF GEOLOGY

[Footnote: The text of the two following papers is taken from the

11th edition of Lyell's Principles of Geology, the last edition

revised by the author.]

I

PREPOSSESSIONS IN REGARD TO THE DURATION OF PAST TIME--PREJUDICES

ARISING FROM OUR PECULIAR POSITION AS INHABITANTS OF THE LAND--

OTHERS OCCASIONED BY OUR NOT SEEING SUBTERRANEAN CHANGES NOW IN

PROGRESS--ALL THESE CAUSES COMBINE TO MAKE THE FORMER COURSE OF

NATURE APPEAR DIFFERENT FROM THE PRESENT--OBJECTIONS TO THE

DOCTRINE THAT CAUSES SIMILAR IN KIND AND ENERGY TO THOSE NOW

ACTING, HAVE PRODUCED THE FORMER CHANGES OF THE EARTH'S SURFACE

CONSIDERED

If we reflect on the history of the progress of geology we

perceive that there have been great fluctuations of opinion

respecting the nature of the causes to which all former changes

of the earth's surface are referable. The first observers

conceived the monuments which the geologist endeavours to

decipher to relate to an original state of the earth, or to a

period when there were causes in activity, distinct, in a kind

and degree, from those now constituting the economy of nature.

These views were gradually modified, and some of them entirely

abandoned, in proportion as observations were multiplied, and the

signs of former mutations were skilfully interpreted. Many

appearances, which had for a long time been regarded as

indicating mysterious and extraordinary agency, were finally

recognised as the necessary result of the laws now governing the

material world; and the discovery of this unlooked-for conformity

has at length induced some philosophers to infer, that, during

the ages contemplated in geology, there has never been any

interruption to the agency of the same uniform laws of change.

The same assemblage of general causes, they conceive, may have

been sufficient to produce, by their various combinations, the

endless diversity of effects, of which the shell of the earth has

preserved the memorials; and, consistently with these principles,

the recurrence of analogous changes is expected by them in time

to come.

Whether we coincide or not in this doctrine we must admit that

the gradual progress of opinion concerning the succession of

phenomena in very remote eras, resembles, in a singular manner,

that which has accompanied the growing intelligence of every

people, in regard to the economy of nature in their own times. In

an early state of advancement, when a greater number of natural

appearances are unintelligible, an eclipse, an earthquake, a

flood, or the approach of a comet, with many other occurrences

afterwards found to belong to the regular course of events, are

regarded as prodigies. The same delusion prevails as to moral

phenomena, and many of these are ascribed to the intervention of

demons, ghosts, witches, and other immaterial and supernatural

agents. By degrees, many of the enigmas of the moral and physical

world are explained, and, instead of being due to extrinsic and

irregular causes, they are found to depend on fixed and

invariable laws. The philosopher at last becomes convinced of the

undeviating uniformity of secondary causes; and, guided by his

faith in this principle, he determines the probability of

accounts transmitted to him of former occurrences, and often

rejects the fabulous tales of former times, on the ground of

their being irreconcilable with the experience of more

enlightened ages.

PREPOSSESSIONS IN REGARD TO THE DURATION OF PAST TIME.--As a

belief in the want of conformity in the cause by which the

earth's crust has been modified in ancient and modern periods

was, for a long time, universally prevalent, and that, too,

amongst men who were convinced that the order of nature had been

uniform for the last several thousand years, every circumstance

which could have influenced their minds and given an undue bias

to their opinions deserves particular attention. Now the reader

may easily satisfy himself, that, however undeviating the course

of nature may have been from the earliest epochs, it was

impossible for the first cultivators of geology to come to such a

conclusion, so long as they were under a delusion as to the age

of the world, and the date of the first creation of animate

beings. However fantastical some theories of the sixteenth

century may now appear to us,--however unworthy of men of great

talent and sound judgment,--we may rest assured that, if the same

misconception now prevailed in regard to the memorials of human

transactions, it would give rise to a similar train of

absurdities. Let us imagine, for example, that Champollion, and

the French and Tuscan literati when engaged in exploring the

antiquities of Egypt, had visited that country with a firm belief

that the banks of the Nile were never peopled by the human race

before the beginning of the nineteenth century, and that their

faith in this dogma was as difficult to shake as the opinion of

our ancestors, that the earth was never the abode of living

beings until the creation of the present continents, and of the

species now existing,--it is easy to perceive what extravagant

systems they would frame, while under the influence of this

delusion, to account for the monuments discovered in Egypt. The

sight of the pyramids, obelisks, colossal statues, and ruined

temples, would fill them with such astonishment, that for a time

they would be as men spell-bound--wholly incapable of reasoning

with sobriety. They might incline at first to refer the

construction of such stupendous works to some superhuman powers

of the primeval world. A system might be invented resembling that

so gravely advanced by, Manetho, who relates that a dynasty of

gods originally ruled in Egypt, of whom Vulcan, the first

monarch, reigned nine thousand years; after whom came Hercules

and other demigods, who were at last succeeded by human kings.

When some fanciful speculations of this kind had amused their

imaginations for a time, some vast repository of mummies would be

discovered, and would immediately undeceive those antiquaries who

enjoyed an opportunity of personally examining them; but the

prejudices of others at a distance, who were not eye-witnesses of

the whole phenomena, would not be so easily overcome. The

concurrent report of many travellers would, indeed, render it

necessary for them to accommodate ancient theories to some of the

new facts, and much wit and ingenuity would be required to modify

and defend their old positions. Each new invention would violate

a greater number of known analogies; for if a theory be required

to embrace some false principle, it becomes more visionary in

proportion as facts are multiplied, as would be the case if

geometers were now required to form an astronomical system on the

assumption of the immobility of the earth.

Amongst other fanciful conjectures concerning the history of

Egypt, we may suppose some of the following to be started. 'As

the banks of the Nile have been so recently colonized for the

first time, the curious substances called mummies could never in

reality have belonged to men. They may have been generated by

some PLASTIC VIRTUE residing in the interior of the earth, or

they may be abortions of Nature produced by her incipient efforts

in the work of creation. For if deformed beings are sometimes

born even now, when the scheme of the universe is fully

developed, many more may have been "sent before their time scarce

half made up," when the planet itself was in the embryo state.

But if these notions appear to derogate from the perfection of

the Divine attributes, and if these mummies be in all their parts

true representations of the human form, may we not refer them to

the future rather than the past? May we not be looking into the

womb of Nature, and not her grave? May not these images be like

the shades of the unborn in Virgil's Elysium--the archetypes of

men not yet called into existence?'

These speculations, if advocated by eloquent writers, would not

fail to attract many zealous votaries, for they would relieve men

from the painful necessity of renouncing preconceived opinions.

Incredible as such scepticism may appear, it has been rivalled by

many systems of the sixteenth and seventeenth centuries, and

among others by that of the learned Falloppio, who, as we have

seen (p. 33), regarded the tusks of fossil elephants as earthly

concretions, and the pottery or fragments of vases in the Monte

Testaceo, near Rome, as works of nature, and not of art. But when

one generation had passed away, and another, not compromised to

the support of antiquated dogmas, had succeeded, they would

review the evidence afforded by mummies more impartially, and

would no longer controvert the preliminary question, that human

beings had lived in Egypt before the nineteenth century: so that

when a hundred years perhaps had been lost, the industry and

talents of the philosopher would be at last directed to the

elucidation of points of real historical importance.

But the above arguments are aimed against one only of many

prejudices with which the earlier geologists had to contend. Even

when they conceded that the earth had been peopled with animate

beings at an earlier period than was at first supposed, they had

no conception that the quantity of time bore so great a

proportion to the historical era as is now generally conceded.

How fatal every error as to the quantity of time must prove to

the introduction of rational views concerning the state of things

in former ages, may be conceived by supposing the annals of the

civil and military transactions of a great nation to be perused

under the impression that they occurred in a period of one

hundred instead of two thousand years. Such a portion of history

would immediately assume the air of a romance; the events would

seem devoid of credibility, and inconsistent with the present

course of human affairs. A crowd of incidents would follow each

other in thick succession. Armies and fleets would appear to be

assembled only to be destroyed, and cities built merely to fall

in ruins. There would be the most violent transitions from

foreign or intestine war to periods of profound peace, and the

works effected during the years of disorder or tranquillity would

appear alike superhuman in magnitude.

He who should study the monuments of the natural world under the

influence of a similar infatuation, must draw a no less

exaggerated picture of the energy and violence of causes, and

must experience the same insurmountable difficulty in reconciling

the former and present state of nature, If we could behold in one

view all the volcanic cones thrown up in Iceland, Italy, Sicily,

and other parts of Europe, during the last five thousand years,

and could see the lavas which have flowed during the same period;

the dislocations, subsidences, and elevations caused during

earthquakes; the lands added to various deltas, or devoured by

the sea, together with the effects of devastation by floods, and

imagine that all these events had happened in one year, we must

form most exalted ideas of the activity of the agents, and the

suddenness of the revolutions. If geologists, therefore, have

misinterpreted the signs of a succession of events, so as to

conclude that centuries were implied where the characters

indicated thousands of years, and thousands of years where the

language of Nature signified millions, they could not, if they

reasoned logically from such false premises, come to any other

conclusion than that the system of the natural world had

undergone a complete revolution.

We should be warranted in ascribing the erection of the great

pyramid to superhuman power, if we were convinced that it was

raised in one day; and if we imagine, in the same manner, a

continent or mountain-chain to have been elevated during an

equally small fraction of the time which was really occupied in

upheaving it, we might then be justified in inferring, that the

subterranean movements were once far more energetic than in our

own times. We know that; during one earthquake the coast of Chili

may be raised for a hundred miles to the average height of about

three feet. A repetition of two thousand shocks, of equal

violence, might produce a mountain-chain one hundred miles long,

and six thousand feet high. Now, should one or two only of these

convulsions happen in a century, it would be consistent with the

order of events experienced by the Chilians from the earliest

times: but if the whole of them were to occur in the next hundred

years, the entire district must be depopulated, scarcely any

animals or plants could survive, and the surface would be one

confused heap of ruin and desolation.

One consequence of undervaluing greatly the quantity of past

time, is the apparent coincidence which it occasions of events

necessarily disconnected, or which are so unusual, that it would

be inconsistent with all calculation of chances to suppose them

to happen at one and the same time. When the unlooked-for

association of such rare phenomena is witnessed in the present

course of nature, it scarcely ever fails to excite a suspicion of

the preternatural in those minds which are not firmly convinced

of the uniform agency of secondary causes;--as if the death of

some individual in whose fate they are interested happens to be

accompanied by the appearance of a luminous meteor, or a comet,

or the shock of an earthquake. It would be only necessary to

multiply such coincidences indefinitely, and the mind of every

philosopher would be disturbed. Now it would be difficult to

exaggerate the number of physical events, many of them most rare

and unconnected in their nature, which were imagined by the

Woodwardian hypothesis to have happened in the course of a few

months: and numerous other examples might be found of popular

geological theories, which require us to imagine that a long

succession of events happened in a brief and almost momentary

period.

Another liability to error, very nearly allied to the former,

arises from the frequent contact of geological monuments

referring to very distant periods of time. We often behold, at

one glance, the effects of causes which have acted at times

incalculably remote, and yet there may be no striking

circumstances to mark the occurrence of a great chasm in the

chronological series of Nature's archives. In the vast interval

of time which may really have elapsed between the results of

operations thus compared, the physical condition of the earth

may, by slow and insensible modifications, have become entirely

altered; one or more races of organic beings may have passed

away, and yet have left behind, in the particular region under

contemplation, no trace of their existence.

To a mind unconscious of these intermediate events, the passage

from one state of things to another must appear so violent, that

the idea of revolutions in the system inevitably suggests itself.

The imagination is as much perplexed by the deception, as it

might be if two distant points in space were suddenly brought

into immediate proximity. Let us suppose, for a moment, that a

philosopher should lie down to sleep in some arctic wilderness,

and then be transferred by a power, such as we read of in tales

of enchantment, to a valley in a tropical country, where, on

awaking, he might find himself surrounded by birds of brilliant

plumage, and all the luxuriance of animal and vegetable forms of

which Nature is so prodigal in those regions. The most reasonable

supposition, perhaps, which he could make, if by the

necromancer's art he were placed in such a situation, would be,

that he was dreaming; and if a geologist form theories under a

similar delusion, we cannot expect him to preserve more

consistency in his speculations, than in the train of ideas in an

ordinary dream.

It may afford, perhaps, a more lively illustration of the

principle here insisted upon, if I recall to the reader's

recollection the legend of the Seven Sleepers. The scene of that

popular fable was placed in the two centuries which elapsed

between the reign of the emperor Decius and the death of

Theodosius the younger. In that interval of time (between the

years 249 and 450 of our era) the union of the Roman empire had

been dissolved, and some of its fairest provinces overrun by the

barbarians of the north. The seat of government had passed from

Rome to Constantinople, and the throne from a pagan persecutor to

a succession of Christian and orthodox princes. The genius of the

empire had been humbled in the dust, and the altars of Diana and

Hercules were on the point of being transferred to Catholic

saints and martyrs. The legend relates, 'that when Decius was

still persecuting the Christians, seven noble youths of Ephesus

concealed themselves in a spacious cavern in the side of an

adjacent mountain, where they were doomed to perish by the

tyrant, who gave orders that the entrance should be firmly

secured with a pile of huge stones. They immediately fell into a

deep slumber, which was miraculously prolonged, without injuring

the powers of life, during a period of 187 years. At the end of

that time the slaves of Adolius, to whom the inheritance of the

mountain had descended, removed the stones to supply materials

for some rustic edifice: the light of the sun darted into the

cavern, and the seven sleepers were permitted to awake. After a

slumber, as they thought, of a few hours, they were pressed by

the calls of hunger, and resolved that Jamhlichus, one of their

number, should secretly return to the city to purchase bread for

the use of his companions. The youth could no longer recognise

the once familiar aspect of his native country, and his surprise

was increased by the appearance of a large cross triumphantly

erected over the principal gate of Ephesus. His singular dress

and obsolete language confounded the baker, to whom he offered an

ancient medal of Decius as the current coin of the empire; and

Jamblichus, on the suspicion of a secret treasure, was dragged

before the judge. Their mutual enquiries produced the amazing

discovery, that two centuries were almost elapsed since

Jamblichus and his friends had escaped from the rage of a pagan

tyrant.'

This legend was received as authentic throughout the Christian

world before the end of the sixth century, and was afterwards

introduced by Mahomet as a divine revelation into the Koran, and

from hence was adopted and adorned by all the nations from Bengal

to Africa who professed the Mahometan faith. Some vestiges even

of a similar tradition have been discovered in Scandinavia. 'This

easy and universal belief,' observes the philosophical historian

of the Decline and Fall, 'so expressive of the sense of mankind,

may be ascribed to the genuine merit of the fable itself. We

imperceptibly advance from youth to age, without observing the

gradual, but incessant, change of human affairs; and even, in our

larger experience of history, the imagination is accustomed, by a

perpetual series of causes and effects, to unite the most distant

revolutions. But if the interval between two memorable eras could

be instantly annihilated; if it were possible, after a momentary

slumber of two hundred years, to display the new world to the

eyes of a spectator who still retained a lively and recent

impression of the old, his surprise and his reflections would

furnish the pleasing subject of a philosophical romance.'

[Footnote: Gibbon, Decline and Fall. chap, xxxiii.]

PREJUDICES ARISING FROM OUR PECULIAR POSITION AS INHABITANTS OF

THE LAND.--The sources of prejudice hitherto considered may be

deemed peculiar for the most part to the infancy of the science,

but others are common to the first cultivators of geology and to

ourselves, and are all singularly calculated to produce the same

deception, and to strengthen our belief that the course of Nature

in the earlier ages differed widely from that now established.

Although these circumstances cannot be fully explained without

assuming some things as proved, which it has been my object

elsewhere to demonstrate, [Footnote: Elements of Geology, 6th

edit., 1865; and Student's Elements, 1871.] it may be well to

allude to them briefly in this place.

The first and greatest difficulty, then, consists in an habitual

unconsciousness that our position as observers is essentially

unfavourable, when we endeavour to estimate the nature and

magnitude of the changes now in progress. In consequence of our

inattention to this subject, we are liable to serious mistakes in

contrasting the present with former states of the globe. As

dwellers on the land, we inhabit about a fourth part of the

surface; and that portion is almost exclusively a theatre of

decay, and not of reproduction. We know, indeed, that new

deposits are annually formed in seas and lakes, and that every

year some new igneous rocks are produced in the bowels of the

earth, but we cannot watch the progress of their formation, and

as they are only present to our minds by the aid of reflection,

it requires an effort both of the reason and the imagination to

appreciate duly their importance. It is, therefore, not

surprising that we estimate very imperfectly the result of

operations thus unseen by us; and that, when analogous results of

former epochs are presented to our inspection, we cannot

immediately recognise the analogy. He who has observed the

quarrying of stone from a rock, and has seen it shipped for some

distant port, and then endeavours to conceive what kind of

edifice will be raised by the materials, is in the same

predicament as a geologist, who, while he is confined to the

land, sees the decomposition of rocks, and the transportation of

matter by rivers to the sea, and then endeavours to picture to

himself the new strata which Nature is building beneath the

waters.

PREJUDICES ARISING FROM OUR NOT SEEING SUBTERRANEAN CHANGES.--Nor

is his position less unfavourable when, beholding a volcanic

eruption, he tries to conceive what changes the column of lava

has produced, in its passage upwards, on the intersected strata;

or what form the melted matter may assume at great depths on

cooling; or what may be the extent of the subterranean rivers and

reservoirs of liquid matter far beneath the surface. It should,

therefore, be remembered, that the task imposed on those who

study the earth's history requires no ordinary share of

discretion; for we are precluded from collating the corresponding

parts of the system of things as it exists now, and as it existed

at former periods. If we were inhabitants of another element--if

the great ocean were our domain, instead of the narrow limits of

the land, our difficulties would be considerably lessened; while,

on the other hand, there can be little doubt, although the reader

may, perhaps, smile at the bare suggestion of such an idea, that

an amphibious being, who should possess our faculties, would

still more easily arrive at sound theoretical opinions in

geology, since he might behold, on the one hand, the

decomposition of rocks in the atmosphere, or the transportation

of matter by running water; and, on the other, examine the

deposition of sediment in the sea, and the imbedding of animal

and vegetable remains in new strata. He might ascertain, by

direct observation, the action of a mountain torrent, as well as

of a marine current; might compare the products of volcanos

poured out upon the land with those ejected beneath the waters;

and might mark, on the one hand, the growth of the forest, and,

on the other, that of the coral reef. Yet, even with these

advantages, he would be liable to fall into the greatest errors,

when endeavouring to reason on rocks of subterranean origin. He

would seek in vain, within the sphere of his observation, for any

direct analogy to the process of their formation, and would

therefore be in danger of attributing them, wherever they are

upraised to view, to some 'primeval state of nature.'

But if we may be allowed so far to indulge the imagination, as to

suppose a being entirely confined to the nether world--some

'dusky melancholy sprite,' like Umbriel, who could 'flit on sooty

pinions to the central earth,' but who was never permitted to

'sully the fair face of light,' and emerge into the regions of

water and of air; and if this being should busy himself in

investigating the structure of the globe, he might frame theories

the exact converse of those usually adopted by human

philosophers. He might infer that the stratified rocks,

containing shells and other organic remains, were the oldest of

created things, belonging to some original and nascent state of

the planet. 'Of these masses' he might say, 'whether they consist

of loose incoherent sand, soft clay, or solid stone, none have

been formed in modern times. Every year some of them are broken

and shattered by earthquakes, or melted by volcanic fire; and

when they cool down slowly from a state of fusion, they assume a

new and more crystalline form, no longer exhibiting that

stratified disposition and those curious impressions and

fantastic markings, by which they were previously characterised.

This process cannot have been carried on for an indefinite time,

for in that case all the stratified rocks would long ere this

have been fused and crystallised. It is therefore probable that

the whole planet once consisted of these mysterious and curiously

bedded formations at a time when the volcanic fire had not yet

been brought into activity. Since that period there seems to have

been a gradual development of heat; and this augmentation we may

expect to continue till the whole globe shall be in a state of

fluidity, or shall consist, in those parts which are not melted,

of volcanic and crystalline rocks.'

Such might be the system of the Gnome at the very time that the

followers of Leibnitz, reasoning on what they saw on the outer

surface, might be teaching the opposite doctrine of gradual

refrigeration, and averring that the earth had begun its career

as a fiery comet, and might be destined hereafter to become a

frozen mass. The tenets of the schools of the nether and of the

upper world would be directly opposed to each other, for both

would partake of the prejudices inevitably resulting from the

continual contemplation of one class of phenomena to the

exclusion of another. Man observes the annual decomposition of

crystalline and igneous rocks, and may sometimes see their

conversion into stratified deposits; but he cannot witness the

reconversion of the sedimentary into the crystalline by

subterranean heat. He is in the habit of regarding all the

sedimentary rocks as more recent than the unstratified, for the

same reason that we may suppose him to fall into the opposite

error if he saw the origin of the igneous class only.

For more than two centuries the shelly strata of the Subapennine

hills afforded matter of speculation to the early geologists of

Italy, and few of them had any suspicion that similar deposits

were then forming in the neighbouring sea. Some imagined that the

strata, so rich in organic remains, instead of being due to

secondary agents, had been so created in the beginning of things

by the fiat of the Almighty. Others, as we have seen, ascribed

the imbedded fossil bodies to some plastic power which resided in

the earth in the early ages of the world. In what manner were

these dogmas at length exploded? The fossil relics were carefully

compared with their living analogues, and all doubts as to their

organic origin were eventually dispelled. So, also, in regard to

the nature of the containing beds of mud, sand, and limestone:

those parts of the bottom of the sea were examined where shells

are now becoming annually entombed in new deposits, Donati

explored the bed of the Adriatic, and found the closest

resemblance between the strata there forming, and those which

constituted hills above a thousand feet high in various parts of

the Italian peninsula. He ascertained by dredging that living

testacea were there grouped together in precisely the same manner

as were their fossil analogues in the inland strata; and while

some of the recent shells of the Adriatic were becoming incrusted

with calcareous rock, be observed that others had been newly

buried in sand and clay, precisely as fossil shells occur in the

Subapennine hills.

In like manner, the volcanic rocks of the Vicentin had been

studied in the beginning of the last century; but no geologist

suspected, before the time of Arduino, that these were composed

of ancient submarine lavas. During many years of controversy, the

popular opinion inclined to a belief that basalt and rocks of the

same class had been precipitated from a chaotic fluid, or an

ocean which rose at successive periods over the continents,

charged with the component elements of the rocks in question. Few

will now dispute that it would have been difficult to invent a

theory more distant from the truth; yet we must cease to wonder

that it gained so many proselytes, when we remember that its

claims to probability arose partly from the very circumstance of

its confirming the assumed want of analogy between geological

causes and those now in action. By what train of investigations

were geologists induced at length to reject these views, and to

assent to the igneous origin of the trappean formations? By an

examination of volcanos now active, and by comparing their

structure and the composition of their lavas with the ancient

trap rocks.

The establishment, from time to time, of numerous points of

identification, drew at length from geologists a reluctant

admission, that there was more correspondence between the

condition of the globe at remote eras and now, and more

uniformity in the laws which have regulated the changes of its

surface, than they at first imagined. If, in this state of the

science, they still despaired of reconciling every class of

geological phenomena to the operations of ordinary causes, even

by straining analogy to the utmost limits of credibility, we

might have expected, at least, that the balance of probability

would now have been presumed to incline towards the close analogy

of the ancient and modern causes. But, after repeated experience

of the failure of attempts to speculate on geological monuments,

as belonging to a distinct order of things, new sects continued

to persevere in the principles adopted by their predecessors.

They still began, as each new problem presented itself, whether

relating to the animate or inanimate world, to assume an original

and dissimilar order of nature; and when at length they

approximated, or entirely came round to an opposite opinion, it

was always with the feeling, that they were conceding what they

had been justified a priori in deeming improbable. In a word, the

same men who, as natural philosophers, would have been most

incredulous respecting any extraordinary deviations from the

known course of nature, if reported to have happened IN THEIR OWN

TIME, were equally disposed, as geologists, to expect the proofs

of such deviations at every period of the past. * * * *

UNIFORMITY OF CHANGE

II

SUPPOSED ALTERNATE PERIODS OF REPOSE AND DISORDER--OBSERVED FACTS

IN WHICH THIS DOCTRINE HAS ORIGINATED--THESE MAY BE EXPLAINED BY

SUPPOSING A UNIFORM AND UNINTERRUPTED SERIES OF CHANGES--THREE-

FOLD CONSIDERATION OF THIS SUBJECT: FIRST, IN REFERENCE TO THE

LAWS WHICH GOVERN THE FORMATION OF FOSSILIFEROUS STRATA, AND THE

SHIFTING OF THE AREAS OF SEDIMENTARY DEPOSITION; SECONDLY, IN

REFERENCE TO THE LIVING CREATION, EXTINCTION OF SPECIES, AND

ORIGIN OF NEW ANIMALS AND PLANTS; THIRDLY, IN REFERENCE TO THE

CHANGES PRODUCED IN THE EARTH'S CRUST BY THE CONTINUANCE OF

SUBTERRANEAN MOVEMENTS IN CERTAIN AREAS, AND THEIR TRANSFERENCE

AFTER LONG PERIODS TO NEW AREAS--ON THE COMBINED INFLUENCE OF ALL

THESE MODES AND CAUSES OF CHANGE IN PRODUCING BREAKS AND CHASMS

IN THE CHAIN OF RECORDS--CONCLUDING REMARKS ON THE IDENTITY OF

THE ANCIENT AND PRESENT SYSTEM OF TERRESTRIAL CHANGES.

ORIGIN OF THE DOCTRINE OF ALTERNATE PERIODS OF REPOSE AND

DISORDER.--It has been truly observed, that when we arrange the

fossiliferous formations in chronological order, they constitute

a broken and defective series of monuments: we pass without any

intermediate gradations from systems of strata which are

horizontal, to other systems which are highly inclined--from

rocks of peculiar mineral composition to others which have a

character wholly distinct--from one assemblage of organic remains

to another, in which frequently nearly all the species, and a

large part of the genera, are different. These violations of

continuity are so common as to constitute in most regions the

rule rather than the exception, and they have been considered by

many geologists as conclusive in favour of sudden revolutions in

the inanimate and animate world. We have already seen that

according to the speculations of some writers, there have been in

the past history of the planet alternate periods of tranquillity

and convulsion, the former enduring for ages, and resembling the

state of things now experienced by man, the other brief,

transient, and paroxysmal, giving rise to new mountains, seas,

and valleys, annihilating one set of organic beings, and ushering

in the creation of another.

It will be the object of the present chapter to demonstrate that

these theoretical views are not borne out by a fair

interpretation of geological monuments. It is true that in the

solid framework of the globe we have a chronological chain of

natural records, many links of which are wanting: but a careful

consideration of all the phenomena leads to the opinion that the

series was originally defective--that it has been rendered still

more so by time--that a great part of what remains is

inaccessible to man, and even of that fraction which is

accessible nine-tenths or more are to this day unexplored.

The readiest way, perhaps, of persuading the reader that we may

dispense with great and sudden revolutions in the geological

order of events is by showing him how a regular and uninterrupted

series of changes in the animate and inanimate world must give

rise to such breaks in the sequence, and such unconformability of

stratified rocks, as are usually thought to imply convulsions and

catastrophes. It is scarcely necessary to state that the order of

events thus assumed to occur, for the sake of illustration,

should be in harmony with all the conclusions legitimately drawn

by geologists from the structure of the earth, and must be

equally in accordance with the changes observed by man to be now

going on in the living as well as in the inorganic creation. It

may be necessary in the present state of science to supply some

part of the assumed course of nature hypothetically; but if so,

this must be done without any violation of probability, and

always consistently with the analogy of what is known both of the

past and present economy of our system. Although the discussion

of so comprehensive a subject must carry the beginner far beyond

his depth, it will also, it is hoped, stimulate his curiosity,

and prepare him to read some elementary treatises on geology with

advantage, and teach him the bearing on that science of the

changes now in progress on the earth. At the same time it may

enable him the better to understand the intimate connection

between the Second and Third Books of this work, one of which is

occupied with the changes of the inorganic, the latter with those

of the organic creation.

In pursuance, then, of the plan above proposed, I will consider

in this chapter, first, the laws which regulate the denudation of

strata and the deposition of sediment; secondly, those which

govern the fluctuation in the animate world; and thirdly, the

mode in which subterranean movements affect the earth's crust.

UNIFORMITY OF CHANGE CONSIDERED, FIRST, IN REFERENCE TO

DENUDATION AND SEDIMENTARY DEPOSITION.--First, in regard to the

laws governing the deposition of new strata. If we survey the

surface of the globe, we immediately perceive that it is

divisible into areas of deposition and non-deposition; or, in

other words, at any given time there are spaces which are the

recipients, others which are not the recipients, of sedimentary

matter. No new strata, for example, are thrown down on dry land,

which remains the same from year to year; whereas, in many parts

of the bottom of seas and lakes, mud, sand, and pebbles are

annually spread out by rivers and currents. There are also great

masses of limestone growing in some seas, chiefly composed of

corals and shells, or, as in the depths of the Atlantic, of

chalky mud made up of foraminifera and diatomaceae.

As to the dry land, so far from being the receptacle of fresh

accessions of matter, it is exposed almost everywhere to waste

away. Forests may be as dense and lofty as those of Brazil, and

may swarm with quadrupeds, birds, and insects, yet at the end of

thousands of years one layer of black mould a few inches thick

may be the sole representative of those myriads of trees, leaves,

flowers, and fruits, those innumerable bones and skeletons of

birds, quadrupeds, and reptiles, which tenanted the fertik

region. Should this land be at length submerged, the waves of the

sea may wash away in a few hours the scanty covering of mould,

and it may merely impart a darker shade of colour to the next

stratum of marl, sand, or other matter newly thrown down. So also

at the bottom of the ocean where no sediment is accumulating,

seaweed, zoophytes, fish, and even shells, may multiply for ages

and decompose, leaving no vestige of their form or substance

behind. Their decay, in water, although more slow, is as certain

and eventually as complete as in the open air. Nor can they be

perpetuated for indefinite periods in a fossil state, unless

imbedded in some matrix which is impervious to water, or which at

least does not allow a free percolation of that fluid,

impregnated, as it usually is, with a slight quantity of carbonic

or other acid. Such a free percolation may be prevented either by

the mineral nature of the matrix itself, or by the superposition

of an impermeable stratum; but if unimpeded, the fossil shell or

bone will be dissolved and removed, particle after particle, and

thus entirely effaced, unless petrifaction or the substitution of

some mineral for the organic matter happen to take place.

That there has been land as well as sea at all former geological

periods, we know from the fact that fossil trees and terrestrial

plants are imbedded in rocks of every age, except those which are

so ancient as to be very imperfectly known to us. Occasionally

lacustrine and fluviatile shells, or the bones of amphibious or

land reptiles, point to the same conclusion. The existence of dry

land at all periods of the past implies, as before mentioned, the

partial deposition of sediment, or its limitation to certain

areas; and the next point to which I shall call the reader's

attention is the shifting of these areas from one region to

another.

First, then, variations in the site of sedimentary deposition are

brought about independently of subterranean movements. There is

always a slight change from year to year, or from century to

century. The sediment of the Rhone, for example, thrown into the

Lake of Geneva, is now conveyed to a spot a mile and a half

distant from that where it accumulated in the tenth century, and

six miles from the point where the delta began originally to

form. We may look forward to the period when this lake will be

filled up, and then the distribution of the transported matter

will be suddenly altered, for the mud and sand brought down from

the Alps will thenceforth, instead of being deposited near

Geneva, be carried nearly 200 miles southwards, where the Rhone

enters the Mediterranean.

In the deltas of large rivers, such as those of the Ganges and

Indus, the mud is first carried down for many centuries through

one arm, and on this being stopped up it is discharged by

another, and may then enter the sea at a point 50 or 100 miles

distant from its first receptacle. The direction of marine

currents is also liable to be changed by various accidents, as by

the heaping up of new sandbanks, or the wearing away of cliffs

and promontories.

But, secondly, all these causes of fluctuation in the sedimentary

areas are entirely subordinate to those great upward or downward

movements of land, which will presently be spoken of, as

prevailing over large tracts of the globe. By such elevation or

subsidence certain spaces are gradually submerged, or made

gradually to emerge: in the one case sedimentary deposition may

be suddenly renewed after having been suspended for one or more

geological periods, in the other as suddenly made to cease after

having continued for ages.

If deposition be renewed after a long interval, the new strata

will usually differ greatly from the sedimentary rocks previously

formed in the same place, and especially if the older rocks have

suffered derangement, which implies a change in the physical

geography of the district since the previous conveyance of

sediment to the same spot. It may happen, however, that, even

where the two groups, the superior and the inferior, are

horizontal and conformable to each other, they may still differ

entirely in mineral character, because, since the origin of the

older formation, the geography of some distant country has been

altered. In that country rocks before concealed may have become

exposed by denudation; volcanos may have burst out and covered

the surface with scoriae and lava; or new lakes, intercepting the

sediment previously conveyed from the upper country, may have

been formed by subsidence; and other fluctuations may have

occurred, by which the materials brought down from thence by

rivers to the sea have acquired a distinct mineral character.

It is well known that the stream of the Mississippi is charged

with sediment of a different colour from that of the Arkansas and

Red Rivers, which are tinged with red mud, derived from rocks of

porphyry and red gypseous clays in 'the far west.' The waters of

the Uruguay, says Darwin, draining a granitic country, are clear

and black, those of the Parana, red. [Footnote: Darwin's Journal,

p. 163, and edit., p. 139.] The mud with which the Indus is

loaded, says Burnes, is of a clayey hue, that of the Chenab, on

the other hand, is reddish, that of the Sutlej is more pale.

[Footnote: Journ. Roy. Geograph. Soc., vol. iii, p. 142.] The

same causes which make these several rivers, sometimes situated

at no great distance the one from the other, to differ greatly in

the character of their sediment, will make the waters draining

the same country at different epochs, especially before and after

great revolutions in physical geography, to be entirely

dissimilar. It is scarcely necessary to add that marine currents

will be affected in an analogous manner in consequence of the

formation of new shoals, the emergence of new islands, the

subsidence of others, the gradual waste of neighbouring coasts,

the growth of new deltas, the increase of coral reefs, volcanic

eruptions, and other changes.

UNIFORMITY OF CHANGE CONSIDERED, SECONDLY, IN REGERENCE TO THE

LIVING CREATION.--Secondly, in regard to the vicissitudes of the

living creation, all are agreed that the successive groups of

sedimentary strata found in the earth's crust are not only

dissimilar in mineral composition for reasons above alluded to,

but are likewise distinguishable from each other by their organic

remains. The general inference drawn from the study and

comparison of the various groups, arranged in chronological

order, is this: that at successive periods distinct tribes of

animals and plants have inhabited the land and waters, and that

the organic types of the newer formations are more analogous to

species now existing than those of more ancient rocks. If we then

turn to the present state of the animate creation, and enquire

whether it has now become fixed and stationary, we discover that,

on the contrary, it is in a state of continual flux--that there

are many causes in action which tend to the extinction of

species, and which are conclusive against the doctrine of their

unlimited durability.

There are also causes which give rise to new varieties and races

in plants and animals, and new forms are continually supplanting

others which had endured for ages. But natural history has been

sucessfully cultivated for so short a period, that a few examples

only of local, and perhaps but one or two of absolute,

extirpation of species can as yet be proved, and these only where

the interference of man has been conspicuous. It will

nevertheless appear evident, from the facts and arguments

detailed in the chapters which treat of the geographical

distribution of species in the next volume, that man is not the

only exterminating agent; and that, independently of his

intervention, the annihilation of species is promoted by the

multiplication and gradual diffusion of every animal or plant. It

will also appear that every alteration in the physical geography

and climate of the globe cannot fail to have the same tendency.

If we proceed still farther, and enquire whether new species are

substituted from time to time for those which die out, we find

that the successive introduction of new forms appears to have

been a constant part of the economy of the terrestrial system,

and if we have no direct proof of the fact it is because the

changes take place so slowly as not to come within the period of

exact scientific observation. To enable the reader to appreciate

the gradual manner in which a passage may have taken place from

an extinct fauna to that now living, I shall say a few words on

the fossils of successive Tertiary periods. When we trace the

series of formations from the more ancient to the more modern, it

is in these Tertiary deposits that we first meet with assemblages

of organic remains having a near analogy to the fauna of certain

parts of the globe in our own time. In the Eocene, or oldest

subdivisions, some few of the testacea belong to existing

species, although almost all of them, and apparently all the

associated vertebrata, are now extinct. These Eocene strata are

succeeded by a great number of more modern deposits, which depart

gradually in the character of their fossils from the Eocene type,

and approach more and more to that of the living creation. In the

present state of science, it is chiefly by the aid of shells that

we are enabled to arrive at these results, for of all classes the

testacea are the most generally diffused in a fossil state, and

may be called the medals principally employed by nature in

recording the chronology of past events. In the Upper Miocene

rocks (No. 5 of the table, p. 135) we begin to find a

considerable number, although still a minority, of recent

species, intermixed with some fossils common to the preceding, or

Eocene, epoch. We then arrive at the Pliocene strata, in which

species now contemporary with man begin to preponderate, and in

the newest of which nine-tenths of the fossils agree with species

still inhabiting the neighbouring sea. It is in the Post-Tertiary

strata, where all the shells agree with species now living, that

we have discovered the first or earliest known remains of man

associated with the bones of quadrupeds, some of which are of

extinct species.

In thus 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 demarcation, 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. Dr. A. Philippi, indeed, after an elaborate

comparison of the fossil tertiary shells of Sicily with those now

living in the Mediterranean, announced, as the result of his

examination, that there are strata in that island which attest a

very gradual passage from a period when only thirteen in a

hundred of the shells were like the species now living in the

sea, to an era when the recent species had attained a proportion

of ninety-five in a hundred. There is, therefore, evidence, he

says, in Sicily of this revolution in the animate world having

been effected 'without the intervention of any convulsion or

abrupt changes, certain species having from time to time died out

and others having been introduced, until at length the existing

fauna was elaborated.'

In no part of Europe is the absence of all signs of man or his

works, in strata of comparatively modern date, more striking than

in Sicily. In the central parts of that island we observe a lofty

table-land and hills, sometimes rising to the height of 3,000

feet, capped with a limestone, in which from 70 to 85 per cent of

the fossil testacea are specifically identical with those now

inhabiting the Mediterranean. These calcareous and other

argillaceous strata of the same age are intersected by deep

valleys which appear to have been gradually formed by denudation,

but have not varied materially in width or depth since Sicily was

first colonised by the Greeks. The limestone, moreover, which is

of so late a date in geological chronology, was quarried for

building those ancient temples of Girgenti and Syracuse, of which

the ruins carry us back to a remote era in human history. If we

are lost in conjectures when speculating on the ages required to

lift up these formations to the height of several thousand feet

above the sea, and to excavate the valleys, how much more remote

must be the era when the same rocks were gradually formed beneath

the waters!

The intense cold of the Glacial period was spoken of in the tenth

chapter. Although we have not yet succeeded in detecting proofs

of the origin of man antecedently to that epoch, we have yet

found evidence that most of the testacea, and not a few of the

quadrupeds, which preceded, were of the same species as those

which followed the extreme cold. To whatever local disturbances

this cold may have given rise in the distribution of species, it

seems to have done little in effecting their annihilation. We may

conclude therefore, from a survey of the tertiary and modern

strata, which constitute a more complete and unbroken series than

rocks of older date, that the extinction and creation of species

have been, and are, the result of a slow and gradual change in

the organic world.

UNIFORMITY OF CHANGE CONSIDERED, THIRDLY, IN REFERENCE TO

SUBTERRANEAN MOVEMENTS.--Thirdly, to pass on to the last of the

three topics before proposed for discussion, the reader will

find, in the account given in the Second Book, Vol. II., of the

earthquakes recorded in history, that certain countries have from

time immemorial, been rudely shaken again and again; while

others, comprising by far the largest part of the globe, have

remained to all appearance motionless. In the regions of

convulsion rocks have been rent asunder, the surface has been

forced up into ridges, chasms have opened, or the ground

throughout large spaces has been permanently lifted up above or

let down below its former level. In the regions of tranquillity

some areas have remained at rest, but others have been

ascertained, by a comparison of measurements made at different

periods, to have risen by an insensible motion, as in Sweden, or

to have subsided very slowly, as in Greenland. That these same

movements, whether ascending or descending, have continued for

ages in the same direction has been established by historical or

geological evidence. Thus we find on the opposite coasts of

Sweden that brackish water deposits, like those now forming in

the Baltic, occur on the eastern side, and upraised strata filled

with purely marine shells, now proper to the ocean, on the

western coast. Both of these have been lifted up to an elevation

of several hundred feet above high-water mark. The rise within

the historical period has not amounted to many yards, but the

greater extent of antecedent upheaval is proved by the occurrence

in inland spots, several hundred feet high, of deposits filled

with fossil shells of species now living either in the ocean or

the Baltic.

It must in general be more difficult to detect proofs of slow and

gradual subsidence than of elevation, but the theory which

accounts for the form of circular coral reefs and lagoon islands,

and which will be explained in the concluding chapter of this

work, will satisfy the reader that there are spaces on the globe,

several thousand miles in circumference, throughout which the

downward movement has predominated for ages, and yet the land has

never, in a single instance, gone down suddenly for several

hundred feet at once. Yet geology demonstrates that the

persistency of subterranean movements in one direction has not

been perpetual throughout all past time. There have been great

oscillations of level, by which a surface of dry land has been

submerged to a depth of several thousand feet, and then at a

period long subsequent raised again and made to emerge. Nor have

the regions now motionless been always at rest; and some of those

which are at present the theatres of reiterated earthquakes have

formerly enjoyed a long continuance of tranquillity. But,

although disturbances have ceased after having long prevailed, or

have recommenced after a suspension for ages, there has been no

universal disruption of the earth's crust or desolation of the

surface since times the most remote. The non-occurrence of such a

general convulsion is proved by the perfect horizontality now

retained by some of the most ancient fossiliferous strata

throughout wide areas.

That the subterranean forces have visited different parts of the

globe at successive periods is inferred chiefly from the

unconformability of strata belonging to groups of different ages.

Thus, for example, on the borders of Wales and Shropshire, we

find the slaty beds of the ancient Silurian system inclined and

vertical, while the beds of the overlying carboniferous shale and

sandstone are horizontal. All are agreed that in such a case the

older set of strata had suffered great disturbance before the

deposition of the newer or carboniferous beds, and that these

last have never since been violently fractured, nor have ever

been bent into folds, whether by sudden or continuous lateral

pressure. On the other hand, the more ancient or Silurian group

suffered only a local derangement, and neither in Wales nor

elsewhere are all the rocks of that age found to be curved or

vertical.

In various parts of Europe, for example, and particularly near

Lake Wener in the south of Sweden, and in many parts of Russia,

the Silurian strata maintain the most perfect horizontality; and

a similar observation may be made respecting limestones and

shales of like antiquity in the great lake district of Canada and

the United States. These older rocks are still as flat and

horizontal as when first formed; yet, since their origin, not

only have most of the actual mountain-chains been uplifted, but

some of the very rocks of which those, mountains are composed

have been formed, some of them by igneous and others by aqueous

action.

It would be easy to multiply instances of similar

unconformability in formations of other ages; but a few more will

suffice. The carboniferous rocks before alluded to as horizontal

on the borders of Wales are vertical in the Mendip hills in

Somersetshire, where the overlying beds of the New Red Sandstone

are horizontal. Again, in the Wolds of Yorkshire the last-

mentioned sandstone supports on its curved and inclined beds the

horizontal Chalk. The Chalk again is vertical on the flanks of

the Pyrenees, and the tertiary strata repose unconformably upon

it.

As almost every country supplies illustrations of the same

phenomena, they who advocate the doctrine of alternate periods of

disorder and repose may appeal to the facts above described, as

proving that every district has been by turns convulsed by

earthquakes and then respited for ages from convulsions. But so

it might with equal truth be affirmed that every part of Europe

has been visited alternately by winter and summer, although it

has always been winter and always summer in some part of the

planet, and neither of these seasons has ever reigned

simultaneously over the entire globe. They have been always

shifting from place to place; but the vicissitudes which recur

thus annually in a single spot are never allowed to interfere

with the invariable uniformity of seasons throughout the whole

planet.

So, in regard to subterranean movements, the theory of the

perpetual uniformity of the force which they exert on the earth's

crust is quite consistent with the admission of their alternate

development and suspension for long and indefinite periods within

limited geographical areas.

If, for reasons before stated, we assume a continual extinction

of species and appearance of others on the globe, it will then

follow that the fossils of strata formed at two distant periods

on the same spot will differ even more certainly than the mineral

composition of those strata. For rocks of the same kind have

sometimes been reproduced in the same district after a long

interval of time; whereas all the evidence derived from fossil

remains is in favour of the opinion that species which have once

died out have never been reproduced. The submergence, then, of

land must be often attended by the commencement of a new class of

sedimentary deposits, characterized by a new set of fossil

animals and plants, while the reconversion of the bed of the sea

into land may arrest at once and for an indefinite time the

formation of geological monuments. Should the land again sink,

strata will again be formed; but one or many entire revolutions

in animal or vegetable life may have been completed in the

interval.

As to the want of completeness in the fossiliferous series, which

may be said to be almost universal, we have only to reflect on

what has been already said of the laws governing sedimentary

deposition, and those which give rise to fluctuations in the

animate world, to be convinced that a very rare combination of

circumstances can alone give rise to such a superposition and

preservation of strata as will bear testimony to the gradual

passage from one state of organic life to another. To produce

such strata nothing less will be requisite than the fortunate

coincidence of the following conditions: first, a never-failing

supply of sediment in the same region throughout a period of vast

duration; secondly, the fitness of the deposit in every part for

the permanent preservation of imbedded fossils; and, thirdly, a

gradual subsidence to prevent the sea or lake from being filled

up and converted into land.

It will appear in the chapter on coral reefs, that, in certain

parts of the Pacific and Indian Oceans, most of these conditions,

if not all, are complied with, and the constant growth of coral,

keeping pace with the sinking of the bottom of the sea, seems to

have gone on so slowly, for such indefinite periods, that the

signs of a gradual change in organic life might probably be

detected in that quarter of the globe if we could explore its

submarine geology. Instead of the growth of coralline limestone,

let us suppose, in some other place, the continuous deposition of

fluviatile mud and sand, such as the Ganges and Brahmapootra have

poured for thousands of years into the Bay of Bengal. Part of

this bay, although of considerable depth, might at length be

filled up before an appreciable amount of change was effected in

the fish, mollusca, and other inhabitants of the sea and

neighbouring land. But if the bottom be lowered by sinking at the

same rate that it is raised by fluviatile mud, the bay can never

be turned into dry land. In that case one new layer of matter may

be superimposed upon another for a thickness of many thousand

feet, and the fossils of the inferior beds may differ greatly

from those entombed in the uppermost, yet every intermediate

gradation may be indicated in the passage from an older to a

newer assemblage of species. Granting, however, that such an

unbroken sequence of monuments may thus be elaborated in certain

parts of the sea, and that the strata happen to be all of them

well adapted to preserve the included fossils from decomposition,

how many accidents must still concur before these submarine

formations will be laid open to our investigation! The whole

deposit must first be raised several thousand feet, in order to

bring into view the very foundation; and during the process of

exposure the superior beds must not be entirely swept away by

denudation.

In the first place, the chances are nearly as three to one

against the mere emergence of the mass above the waters, because

nearly three-fourths of the globe are covered by the ocean. But

if it be upheaved and made to constitute part of the dry land, it

must also, before it can be available for our instruction, become

part of that area already surveyed by geologists. In this small

fraction of land already explored, and still very imperfectly

known, we are required to find a set of strata deposited under

peculiar conditions, and which, having been originally of limited

extent, would have been probably much lessened by subsequent

denudation.

Yet it is precisely because we do not encounter at every step the

evidence of such gradations from one state of the organic world

to another, that so many geologists have embraced the doctrine of

great and sudden revolutions in the history of the animate world.

Not content with simply availing themselves, for the convenience

of classification, of those gaps and chasms which here and there

interrupt the continuity of the chronological series, as at

present known, they deduce, from the frequency of these breaks in

the chain of records, an irregular mode of succession in the

events themselves, both in the organic and inorganic world. But,

besides that some links of the chain which once existed are now

entirely lost and others concealed from view, we have good reason to

suspect that it was never complete originally.

It may undoubtedly be said that strata have been always forming

somewhere, and therefore at every moment of past time Nature has

added a page to her archives; but, in reference to this subject, it

should be remembered that we can never hope to compile a consecutive

history by gathering together monuments which were originally

detached and scattered over the globe. For, as the species of organic

beings contemporaneously inhabiting remote regions are distinct, the

fossils of the first of several periods which may be preserved in any

one country, as in America for example, will have no connection with

those of a second period found in India, and will therefore no more

enable us to trace the signs of a gradual change in the living

creation, than a fragment of Chinese history will fill up a blank in

the political annals of Europe.

The absence of any deposits of importance containing recent shells in

Chili, or anywhere on the western coast of South America, naturally

led Mr. Darwin to the conclusion that "where the bed of the sea is

either stationary or rising, circumstances are far less favourable

than where the level is sinking to the accumulation of conchiferous

strata of sufficient thickness and extension to resist the average

vast amount of denudation." [Footnote: Darwin's S. America, pp. 136,

139.] In like manner the beds of superficial sand, clay, and gravel,

with recent shells, on the coasts of Norway and Sweden, where the

land has risen in Post-tertiary times, are so thin and scanty as to

incline us to admit a similar proposition. We may in fact assume that

in all cases where the bottom of the sea has been undergoing

continuous elevation, the total thickness of sedimentary matter

accumulating at depths suited to the habitation of most of the

species of shells can never be great, nor can the deposits be thickly

covered by superincumbent matter, so as to be consolidated by

pressure. When they are upheaved, therefore, the waves on the beach

will bear down and disperse the loose materials; whereas, if the bed

of the sea subsides slowly, a mass of strata, containing abundance of

such species as live at moderate depths, may be formed and may

increase in thickness to any amount. It may also extend horizontally

over a broad area, as the water gradually encroaches on the subsiding

land.

Hence it will follow that great violations of continuity in the

chronological series of fossiliferous rocks will always exist, and

the imperfection of the record, though lessened, will never be

removed by future discoveries. For not only will no deposits

originate on the dry land, but those formed in the sea near land,

which is undergoing constant upheaval, will usually be too slight in

thickness to endure for ages.

In proportion as we become acquainted with larger geographical areas,

many of the gaps, by which a chronological table, like that given at

page 135, is rendered defective, will be removed. We were enabled by

aid of the labours of Prof. Sedgwick and Sir Roderick Murchison to

intercalate, in 1838, the marine strata of the Devonian period, with

their fossil shells, corals, and fish, between the Silurian and

Carboniferous rocks. Previously the marine fauna of these last-

mentioned formations wanted the connecting links which now render the

passage from the one to the other much less abrupt. In like manner

the Upper Miocene has no representative in England, but in France,

Germany, and Switzerland it constitutes a most instructive link

between the living creation and the middle of the great Tertiary

period. Still we must expect, for reasons before stated, that chasms

will for ever continue to occur, in some parts of our sedimentary

series.

Concluding remarks on the consistency of the theory of gradual change

with the existence of great breaks in the series.--To return to the

general argument pursued in this chapter, it is assumed, for reasons

above explained, that a slow change of species is in simultaneous

operation everywhere throughout the habitable surface of sea and

land; whereas the fossilisation of plants and animals is confined to

those areas where new strata are produced. These areas, as we have

seen, are always shifting their position, so that the fossilising

process, by means of which the commemoration of the particular state

of the organic world, at any given time, is effected, may be said to

move about, visiting and revisiting different tracts in succession.

To make still more clear the supposed working of this machinery, 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 births 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

those 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 the intervals 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. There are, undoubtedly, other causes,

besides the mere quantity of time, which may augment or diminish the

amount of discrepancy. Thus, at some periods a pestilential disease

may have lessened the average duration of human life; or a variety of

circumstances may have caused the births to be unusually numerous,

and the population to multiply; or a province may be suddenly

colonised by persons migrating from surrounding districts.

These exceptions may be compared to the accelerated rate of

fluctuations in the fauna and flora of a particular region, in which

the climate and physical geography may be undergoing an extraordinary

degree of alteration.

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

pretensions 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 fossilised,

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 equidistant 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

dying-out and renovation of 'species.

As all the conclusions above insisted on are directly opposed to

opinions still popular, I shall add another comparison, in the hope

of preventing any possible misapprehension of the argument. Suppose

we had discovered two buried cities at the foot of Vesuvius,

immediately superimposed upon each other, with a great mass of tuff

and lava intervening, just as Portici and Resina, if now covered with

ashes, would overlie Herculaneum. An antiquary might possibly be

entitled to infer, from the inscriptions on public edifices, that the

inhabitants of the inferior and older city were Greeks, and those of

the modern towns Italians. But he would reason vary hastily if he

also concluded from these data, that there had been a sudden change

from the Greek to the Italian language in Campania. But if he

afterwards found three buried cities, one above the other, the

intermediate one being Roman, while, as in the former example, the

lowest was Greek and the uppermost Italian, he would then perceive

the fallacy of his former opinion, and would begin to suspect that

the catastrophes, by which the cities were inhumed might have no

relation whatever to the fluctuations in the language of the

inhabitants; and that, as the Roman tongue had evidently intervened

between the Greek and Italian, so many other dialects may have been

spoken in succession, and the passage from the Greek to the Italian

may have been very gradual, some terms growing obsolete, while others

were introduced from time to time.

If this antiquary could have shown that the volcanic paroxysms of

Vesuvius were so governed as that cities should be buried one above

the other, just as often as any variation occurred in the language of

the inhabitants, then, Indeed, the abrupt passage from a Greek to a

Roman, and from a Roman to an Italian city, would afford proof of

fluctuations no less sudden in the language of the people.

So, in Geology, if we could assume that it is part of the plan of

Nature to preserve, in every region of the globe, an unbroken series

of monuments to commemorate the vicissitudes of the organic creation,

we might infer the sudden extirpation of species, and the

simultaneous introduction o! others, as often as two formations in

contact are found to include dissimilar organic fossils. But we must

shut our eyes to the whole economy of the existing causes, aqueous,

igneous, and organic, if we fail to perceive that such is not the

plan of Nature.

I shall now conclude the discussion of a question with which we have

been occupied since the beginning of the fifth chapter--namely,

whether there has been any interruption, from the remotest periods,

of one uniform and continuous system of change in the animate and

inanimate world. We were induced to enter into that enquiry by

reflecting how much the progress of opinion in Geology had been

influenced by the assumption that the analogy was slight in kind, and

still more slight in degree, between the cases which produced the

former revolutions of the globe, and those now in every-day

operation. It appeared clear that the earlier geologists had not only

a scanty acquaintance with existing changes, but were singularly

unconscious of the amount of their ignorance. With the presumption

naturally inspired by this unconsciousness, they had no hesitation in

deciding at once that time could never enable the existing powers of

nature to work out changes of great magnitude, still less such

important revolutions as those which are brought to light by Geology.

They therefore felt themselves at liberty to indulge their

imaginations in guessing at what might be, rather than enquiring what

is; in other words, they employed themselves in conjecturing what

might have been the course of Nature at a remote period, rather than

in the investigation of what was the course of Nature in their own

times.

It appeared to them far more philosophical to speculate on the

possibilities of the past, than patiently to explore the realities of

the present; and having invented theories under the influence of such

maxims, they were consistently unwilling to test their validity by

the criterion of their accordance with the ordinary operations of

Nature. On the contrary. the claims of each new hypothesis to

credibility appeared enhanced by the great contrast, in kind or

intensity, of the causes referred to and those now in operation.

Never was there a dogma more calculated to foster indolence, and to

blunt the keen edge of curiosity, than this assumption of the

discordance between the ancient and existing causes of change. It

produced a state of mind unfavourable in the highest degree to the

candid reception of the evidence of those minute but incessant

alterations which every part of the earth's surface is undergoing,

and by which the condition of its living inhabitants is continually

made to vary. The student, instead of being encouraged with the hope

of interpreting the enigmas presented to him in the earth's

structure--instead of being prompted to undertake laborious enquiries

into the natural history of the organic world, and the complicated

effects of the igneous and aqueous causes now in operation--was

taught to despond from the first. Geology, it was affirmed, could

never rise to the rank of an exact science; the greater number of

phenomena must for ever remain inexplicable, or only be partially

elucidated by ingenious conjectures. Even the mystery which invested

the subject was said to constitute one of its principal charms,

affording, as it did, full scope to the fancy to indulge in a

boundless field of speculation.

The course directly opposed to this method of philosophising consists

in an earnest and patient enquiry, how far geological appearances are

reconcilable with the effect of changes now in progress, or which may

be in progress in regions inaccessible to us, but of which the

reality is attested by volcanos and subterranean movements. It also

endeavours to estimate the aggregate result of ordinary operations

multiplied by time, and cherishes a sanguine hope that the resources

to be derived from observation and experiment, or from the study of

Nature such as she now is, are very far from being exhausted. For

this reason all theories are rejected which involve the assumption of

sudden and violent catastrophes and revolutions of the whole earth,

and its inhabitants--theories which are restrained by no reference to

existing analogies, and in which a desire is manifested to cut,

rather than patiently to untie, the Gordian knot.

We have now, at least, the advantage of knowing, from experience,

that an opposite method has always put geologists on the road that

leads to truth--suggesting views which, although imperfect at first,

have been found capable of improvement, until at last adopted by

universal consent; while the method of speculating on a former

distinct state of things and causes has led invariably to a multitude

of contradictory systems, which have been overthrown one after the

other--have been found incapable of modification--and which have

often required to be precisely reversed.

The remainder of this work will be devoted to an investigation of the

changes now going on in the crust of the earth and its inhabitants.

The importance which the student will attach to such researches will

mainly depend on the degree of confidence which he feels in the

principles above expounded. If he firmly believes in the resemblance

or identity of the ancient and present system of terrestrial changes,

he will regard every fact collected respecting the cause in diurnal

action as affording him a key to the interpretation of some mystery

in the past. Events which have occurred at the most distant periods

in the animate and inanimate world will be acknowledged to throw

light on each other, and the deficiency of our information respecting

some of the most obscure parts of the present creation will be

removed. For as, by studying the external configuration of the

existing land and its inhabitants, we may restore in imagination the

appearance of the ancient continents which have passed away, so may

we obtain from the deposits of ancient seas and lakes an insight into

the nature of the subaqueous processes now in operation, and of many

forms of organic life which, though now existing, are veiled from

sight. Rocks, also, produced by subterranean fire in former ages, at

great depths in the bowels of the earth, present us, when upraised by

gradual movements, and exposed to the light of heaven, with an image

of those changes which the deep-seated volcano may now occasion in

the nether regions. Thus, although we are mere sojourner's on the

surface of the planet, chained to a mere point in space, enduring but

for a moment of time, the human mind is not only enabled to number

worlds beyond the unassisted ken of mortal eye, but to trace the

events of indefinite ages before the creation of our race, and is not

even withheld from penetrating into the dark secrets of the ocean, or

the interior of the solid globe; free, like the spirit which the poet

described as animating the universe,

------ire per omnes

Terrasque, tractusque maris, ccelumque profisndutn.

[Footnote: "To go through all binds, and the tracts of the ocean, and

the boundless heaven."]

End of Project Gutenberg's The Harvard Classics Volume 38, by Various