HEROES OF GEOLOGY.
The rise of the science which treats of the ancient history
of the earth—Students of the present changes, which are
the examples by which the past may be comprehended—The
Greeks—The life of Pythagoras; a notice of the geology of
Aristoteles—Strabo’s life—The nature of fossils and the life of
Steno.
As was the case in the other branches of natural history already noticed,
the Greeks knew much more about geology than did the nations of the rest
of Europe, subsequently, for nearly seventeen hundred years. The first
recorded teacher of the ancient history of the earth was Pythagoras, who
was born on the island of Samos, about the year 570 B.C. By his mother’s
side he was connected with the principal families of the island, and
his father appears to have been a Phœnician or a Tyrrhenian of Lemnos.
There is nothing known about his childhood, and it is evident that he
studied under the great philosophers of his age in Greece. But he wanted
further information, and therefore travelled into Egypt, and thence into
Chaldæa. Polycrates, the ruler of the island in which Pythagoras was
born, appears to have assisted him with the Egyptians by introductions.
The traveller noticed not only the habits and customs of the people he
visited, but also the aspect of the countries, and the method by which
nature wore the earth, and produced changes on the surface of the ground.
He appears to have been much struck with the periodical nature of many
natural events, such as the succession of the seasons, the time of rain
and inundation, and of great heat, and of all the common examples with
which everyone is familiar at the present day. Returning home he soon
became aware that he could not teach, unreservedly, what he had learned
and discovered during his travels, for fear of Polycrates, and he left
the island. Finally he settled at Croton, in southern Italy, and he
appears to have chosen the locality, in order to propagate his moral and
political, as well as scientific opinions. Unfortunately, this ardent
scholar and teacher did not write any books, but left that task to
his pupils and successors, so that much good sense is mixed with much
nonsense in the so-called doctrines of Pythagoras which came from them.
Some of his opinions are very remarkable and striking, and he introduced
into his own country the statements of the Eastern nations, that there
has been a gradual deterioration of the human race from an original state
of virtue and happiness. But his principal work regarding the earth
has descended to us through the poet Ovid, and it is most interesting.
Pythagoras insisted that there was a perpetual and gradual system of
change, inherent in the earth. This idea, which came into his mind from
the results of observation, he did not apply to very remote ages, or to
what is now called the ancient history of the globe. He simply insisted
on modern changes. Really this limiting of his thought was in the true
scientific spirit, and he dealt with what was true and proveable so far
as he was concerned. It might be supposed that the present changes cannot
come within the studies of the geologist, but they really do so, because,
as will be noticed further on in considering the life of Hutton, the past
history of the earth can only be comprehended by studying the present
state of things. Pythagoras cleared the way, and made a path for the
geologist. He is said by Ovid to have taught as follows:—
“Nothing perishes in this world, but things simply vary and change
their form. To be born means simply that a thing begins to be something
different from what it was before; and dying is ceasing from being the
same thing. Solid land has been converted into sea. Sea has been changed
into land; marine shells lie far distant from the deep, and the anchor
has been found on the summit of the hills. Valleys have been excavated by
running water, and floods have washed down hills into the sea. Marshes
have become dry ground. Dry lands have changed into stagnant pools.
During earthquakes some springs have been closed up, and new ones have
broken out. Rivers have deserted their channels, and have been reborn
elsewhere; as the Erasinus, in Greece, and Mysius, in Asia. The waters of
some rivers, formerly sweet, have become bitter, as those of Anigrus, in
Greece. Islands have become connected with the main land, by the growth
of deltas and new deposits. Peninsulas have been divided from the main
land, and have become islands, as Leucadia; and according to tradition,
Sicily, the sea having carried away the isthmus. Land has been submerged
by earthquakes. The Grecian cities of Helice and Burris, for example, are
to be seen under the sea, with their walls inclined. Plains have been
upheaved into hills by the confined air seeking vent, as at Trœzene, in
the Peloponnesus. There are streams which have a petrifying power, and
convert the substances which they touch into marble. Volcano vents shift
their positions. There was a time when Etna was not a burning mountain,
and the time will come when it will cease to burn; whether it be that
some caverns be closed up by the movements of the earth and others
opened, or whether the fuel is finally exhausted.”
Of course there are several errors in these statements, and especially
those which relate to the causes of volcanic vents are absurd.
Pythagoras also noticed the changes in the animal kingdoms, such as the
metamorphoses of insects. Besides being a naturalist this great man
taught some most extraordinary doctrines for his time of the world and
nation. He stated that virtue was with him and his followers, a harmony,
unity, and an endeavour to resemble the Deity. The whole life of man
should be an attempt to represent, on earth, the beauty and harmony
displayed in the order of the universe. The mind should have the body
and the passions under perfect control; the gods should be worshipped by
simple purifications and offerings, and above all by sincerity and purity
of heart. Pythagoras, by his good teaching and example, established a
great school of philosophy, which influenced the world subsequently in
a marked manner. A political riot dispersed his followers, and he died
about 504 B.C.
A notice of the life of Aristoteles as botanist and zoologist has
already been given, and now a few words must be said about the opinions
held by this very remarkable man regarding changes in the earth. He
progressed beyond Pythagoras, for he refers to many examples of changes
now constantly going on, and insists, emphatically, on the great results
which they must produce _in the lapse of ages_. The changes of the
earth, he says, are so slow in comparison to the duration of our lives,
that they are overlooked, and the migrations of people after great
catastrophes, and their removal to other regions, cause the event to be
forgotten. In one work Aristoteles wrote: “The distribution of land and
sea, in particular regions, does not endure throughout all time, but it
becomes sea in those parts where it was land, and again it becomes land
where it was sea; and there is reason for thinking that these changes
take place according to a certain system and within a certain period.
Everything changes in the course of time.”
There was a great geographer called Strabo, about whose life little is
known, except that he travelled far and wide in Europe and North Africa,
and wrote largely on the earth. He did not content himself with simple
geography, however, for he entered into a discussion, which was a very
common one in those days, as it has been since, concerning the nature of
the fossil shells which are found in strata or layers of the earth remote
from the sea. He attributed the collecting of the shells where they
are found to the former subsidence of the land, and not to the rising
of the sea. It is not, he said, because the lands covered by seas were
originally at different altitudes, that the waters have risen or subsided
or receded from some parts and inundated others, but the reason is, that
the same land is sometimes raised up and sometimes depressed, so that it
either overflows or returns to its own place again. We must therefore
ascribe the cause to the ground, either to that ground which is under
the sea or to that which becomes flooded by it, but rather to that which
lies beneath the sea, for this is more moveable, and on account of its
humidity can be altered with greater celerity. This philosopher clearly
laid down the law that the general level of the sea has remained the
same, but that it has been and is the land which has been or is upheaved
or subsided. It is a fundamental truth on which much of the science of
geology depends. He moreover asserted that volcanoes were safety-valves,
and were the result of subterranean convulsions.
These were the principal writers which influenced geology in the days
before the Christian era, and it is to be noticed that they did not treat
of the construction of the rocks, of the succession of the layers or
strata, or of much concerning the ancient history of the globe. But they
taught, wisely and admirably, the nature of modern changes, and believed
that these and the older ones they could comprehend, were part of a
scheme, and were produced by natural causes, in the course of events.
Aristoteles, Strabo, and Plinius wrote about the changes which were
progressing on the surface of the earth, and compared them, in their
reasoning, with changes they presumed had been, but still no great
advance was made.
In the early part of the sixteenth century a remarkable discussion sprang
up about the nature of shells and bones, which were found in layers of
earth remote from the sea. The celebrated painter Leonardo da Vinci had
seen some of these fossils during his youth, when he planned and carried
out some important canals in the north of Italy. He laughed at the
fancies of the day about the shells, for some people said that they were
made by the stars, and others that they were brought forth naturally, in
the layers of earth in which they were found. He wanted to know where the
things were being made in the hills, by the stars, at the present time,
and stated that, like the rounded stones of gravel, the shells had been
in the sea, and that they were of different ages and kinds, and were once
alive. But the former living condition of fossils, and the possibility of
their being understood, by comparing them with recent or living things,
was, perhaps, most strongly put by Steno, a Dane.
In 1638, a goldsmith, Steno by name, living at Copenhagen, who was a
tradesman of the King Christian IV. of Denmark, had a son. The young
Nicholas was brought up carefully, evidently was well educated, and was
destined for the medical profession. A strict Lutheran, he naturally
went to Holland for a part of his education, and studied at Leyden under
the very distinguished anatomists there, after he had taken his degree.
Nothing is known about his person or habits, but the results of his
constant labour prove him to have been a most industrious student, and
also an investigator of the human frame in his early days of manhood.
At first the medical profession was everything to him, and he studied
human anatomy and physiology with great success, making some important
and interesting discoveries. He discovered the duct or channel by which
the saliva runs into the mouth from the salivary gland beneath the skin
on the cheek, and in 1664 he published some researches on the manner
in which the chick is nourished in the egg. Moreover, he examined the
structures of the eye of the calf, the nature of the mucous secretion,
and wrote on the heart. While engaged in these researches at Amsterdam,
he heard of the death of his mother, and returned to Copenhagen. After a
short stay there, he set out for Italy, taking France on his way; and he
began a series of researches on the structure of the brain at Paris in
1664. Here a great change occurred, which influenced his future life in a
remarkable degree. Steno, well known then as a successful investigator,
came under the notice of a great French geographer, Thévenot, and, what
was more important, became the friend of Bossuet, one of the greatest
preachers and teachers the Roman Catholic Church has ever produced.
Steno was so influenced by Bossuet, that he became converted to the
Roman Catholic faith, and left the Lutheran Church. Going subsequently
into Italy, Steno pursued his studies, and settled in Florence, in
1667, being well received by the Grand Duke Ferdinand II. de Medici. In
spite of the somewhat natural jealousy of the medical men of the city,
Steno was appointed physician to the Grand Duke, and prosecuted his
anatomical studies under his influence. Then he came across a subject
which directed his attention to geology, or rather to that part of the
science which relates to extinct animals. In a letter to Thévenot, Steno
describes the dissection of a shark which had been captured off Leghorn
in 1666, and especially discussed the mode of growth of the teeth of the
animal. At this time many fossils were picked up and gathered out of
layers or strata, which were called by many curious names, and believed
to be anything but what they really were. They were distinguished by
Steno at once as shark’s teeth, and he insisted that sharks lived during
the former ages of the globe, and that they had become entombed in the
deposits which were then forming a stratum or layer of earth, the result
of deposition in water, being the burial-ground of the time of its
collection or formation.
Fossils were thus shown by Steno to be mineralized or petrified organic
remains, and he gave the hint or method to future investigators, that
the example of the existing animals must be taken, in order to learn
the nature of those creatures whose remains are more or less perfectly
preserved in the fossil condition.
Following out this subject, Steno wrote on the manner in which deposits
accumulate, and accumulated in past ages; and he concluded that if we
found a deposit containing sea-salt and the remains of marine animals,
planks of ships etc., we should believe that the sea had once been there,
whether the bed was exposed in consequence of the sea having retired,
or because the land had been raised. He showed that although the lowest
beds deposited over any area, must conform to the shape of the underlying
rock, the tendency of all sediment must be to occupy the horizontal
position; and so when we find them highly inclined, as in mountains, for
instance, we must refer this to subsequent movement. He noticed that
mountains are made up both of horizontal and inclined strata, as may
be seen along their flanks. He infers that mountains were once not in
existence, and that they do not grow, but that their regions are raised
and depressed and subject to rending and fissuring. Steno clearly showed
that the land had sunk and had been again elevated in the geological
ages, and in considering the causes he seems to have grasped the idea
that the internal heat of the earth becoming less, the mass cools, and
that the movements on the surface have had to do with the cooling. His
most important work was removing fossils out of the category of marvels,
sports of nature, and as things which grew in the earth, to the proper
truth that they are preserved parts of animals and plants which were
formerly alive. In 1688, Steno was appointed to the chair of anatomy
at Copenhagen; but he had to suffer from jealousy, and doubtless some
religious persecution influenced his desire to leave his native country
and to return to Florence again. This he did, and Cosmo III. entrusted
him with the education of his son. Steno then began to give up science
and to study theology, and wrote several works on the subject by which he
hoped to convert his old natural history friends. One of these involved
him in a controversy with the reformed clergy of Jena. The Pope, Innocent
XI., rewarded Steno in 1677, by making him a bishop and apostolic vicar
of Northern Europe. Steno went to reside at Hanover; but he had to leave,
and returning to Schwerin, he died there. His body was, at the request of
the Grand Duke Cosmo, carried back to Tuscany in 1687.
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