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The history of the natural sciences may be likened to a book which has been read a little from time to time, but of which no one has gained a full knowledge.
And this is especially true of geology, the science that treats of the history of the earth.
The Greeks, with their eager thirst for knowledge, and untiring zeal in its pursuit, had opened this wonder—book of nature, and read some of the secrets revealed in its fascinating pages, but, as was the case with many other branches of science, the knowledge thus gained consisted more of isolated facts than of any deep comprehension of the great laws which underlie the workings of nature.
Pythagoras, in his journeys through Egypt and Chaldea, noticed the different appearances of the land, and made some observations on the subject, taking for his starting—point the idea of continual change. "Nothing," said he, "perishes, but all things change their form," and it was to these constant changes changes that he claimed all the phenomena connected with the earth were due.
After Pythagoras, other Greek philosophers took up the story where he left off, and read a little further on; but the knowledge thus gained was not of a kind to explain any of the secrets that were hidden in the earth, and can only be likened to the pictures scattered through a volume, and which are understood only when one has read the printed page.
And then for many centuries the history of the earth was like a closed book, and even when astronomy, botany, electricity, and other subjects had received earnest study by the great men of science, geology was still an unexplored region.
Men had learned to count the stars of heaven, to number the flowers of the field, and to control some of the subtlest forces of nature long before any serious attempt was made to read the history of the earth, and all the wonders that lay before their eyes were only regarded as unexplained, and perhaps inexplainable mysteries.
In the old days the popular belief that the interior of the earth was inhabited by races of beings who performed all the miracles of nature, was esteemed a sufficient explanation, and all the vast mineral wealth that is stored away in the earth's great treasure chambers was supposed to be the work of the kind genii who bestowed their riches with lavish hands upon their human favorites.
But it was only in the dark ages of science that this belief could be held, and when nature's wonders ceased to be regarded with the unreasoning awe which the general attendant of ignorance, and it was no longer considered irreligious to study the workings of the universe, then the old superstitions faded away, and man required a more intelligent answer to his questions as to the causes of the wonderful effects that were everywhere visible.
And although geology is one of the sciences that have been very lately developed, yet, when once aroused, the interest in it became so strong that it was pursued with an ardor that soon brought about great results. The earth suddenly ceased to be regarded simply as the abode of man, and interesting only because it produced the wherewithal to supply his needs.
It came to be looked upon instead as a thing in itself so wonderul and with a history of such antiquity, that man's experience seemed insignificant beside it, and geology was clothed with an interest as great as that attached to astronomy when the telescope suddenly revealed the existence of the great star-systems of the remote heavens which had been hitherto invisible to the human eye.
And then came study and research of the most absorbing nature, and in the new light thus given them, men saw even new and greater beauty. Before this the interior of the earth had been considered as a great treasure house, whose largess might be his who would seek it; but now it was found that the rich veins of gold and silver which streamed through the earth, like the rivers that flowed over its surface, the secret mines that held the priceless diamonds and rubies in their hidden chambers, and the great coal measures whose layers bore the impress of the lily and the palm that had perished in dim—forgotten ages, could all tell the magic story of their birth to one who had the gift of hearing their voices.
And the wise seekers after knowledge listened with reverent attention, and gathered what wisdom they could, and thus a little of the marvellous history of the earth was learned.
Chief among these earnest seekers was Charles Lyell, who was born at Kinnordy, Forfarshire, Scotland, November 14, 1797.
Although an intelligent and observing child, Lyell did not show any particular love for nature until his eleventh year, when ill—health made it necessary for him to leave school and go home for a few months.
Then the absence of playfellows, and the bent of his mind toward some absorbing occupation, first led him to notice the world of nature that he had hitherto neglected, and all the myriad forms of life that he saw were suddenly endowed with an unexpected interest.
His attention was thus directed toward the study of the animal kingdom, and he began to observe carefully, if not methodically, the habits and peculiarities of insects.
It happened that his father also had been interested in this branch of study, and the family library was furnished with some valuable volumes on entomology, the illustrations of which served to teach Lyell the names and localities of the butterflies, moths, and aquatic insects that he began to collect.
Although he was not conscious of it, his investigations were carried on in the true scientific spirit, including the study of the insects, particularly of the butterfly, from the hatching of the caterpillar, through the transformation of the chrysalis; while at the same time he learned to discriminate so nicely between the several hundred species that he soon became familiar with, that the names which he gave to certain tribes, such as "the fold—up moths," "the yellow underwings," etc., were afterward found by him to really indicate the natural families of classification.
This pursuit did not meet with the sympathy of the people at home, and young Lyell had to endure much bantering and ridicule in consequence of it, but this did not daunt his enthusiasm, and his persistence clearly indicated the spirit of the true seeker after wisdom who lets nothing turn him aside from the path he has chosen. Lyell's collection of insects made at this time was valuable, even though his methods of preserving the specimens were often unscientific and injurious, and he had the satisfaction in after years of knowing that the butterflies and moths which he captured and preserved with so much patience, finding inspiration and help in his work only from the printed pages of Linnaeus and other naturalists, was considered of sufficient value to be utilized by one of the first entomologists in England.
From this time Lyell's appreciation of nature never failed, and his usual boyish pursuits received new zest whenever they approached the region of living forms; and when he returned to school his ardor by no means decreased; the favorite amusement of birds'—nesting being turned by him to an advantage which resulted in a knowledge of the eggs of almost every bird in that region, which was particularly rich in varieties.
The love of one branch of natural scieince invariably leads to an interest in others, for in the world of nature all things are so closely allied that an interest in one presupposes an interest in all, and thus it happened that Lyell's taste for entomology eventually led to the selection of his life's work.
When he was seventeen he entered Oxford, and although he pursued the regular course with a fair amount of interest, he still showed a love for the works of nature which distinguished him from his companions.
He continued his studies of insects in his leisure hours, having at this time the assistance of an experienced naturalist, and it was during this period also that he became aware that there was such a science as geology, and that the history of the earth might be studied with the same exactness as distinguished the classification of animals and plants.
The knowledge that the earth, which he had hitherto regarded only as the abode of man, possessed an antiquity far exceeding the most remote history of the human race, excited his imagination to such a degree that he knew no rest until he undertook a course in geology. He was thus led to an interest in fossils, and at once began to form acquaintances among collectors, recognizing in one instance the house of a prominent naturalist by a large ammonite which he saw at the door.
From the time of his second year at Oxford geology occupied a prominent part in Lyell's mind, and the study of the earth became gradually of absorbing interest; and he was more and more amazed to find that, while science had progressed in every other department, the earth still remained almost as great a mystery as it had been in the first dawn of scientific thought.
The genius of Galileo and Herschel had read the secret of the heavens, and mapped out the star-system so that remote space had long since ceased to be regarded as an unknown region, and the astronomer could find the orb he sought with the same ease that one might walk into a garden and pluck a favorite flower.
Kepler and Newton had formulated the great laws of planetary motion, and the discoveries in electricity had revealed a subtle force which pervaded all nature to an extent that had not been dreamed of before. Linnaeus had demonstrated the order which harmonized the animal and vegetable worlds, and chemistry had brought to light the unsuspected resources of nature, but as yet no one had given a theory of the earth's history which would satisfactorily account for its present state, and place geology among the familiar sciences.
Besides the gold and gems, other things served to tell man of the wonders of the earth; the fossils found in Europe, in America, and in Asia showed that the earth had undergone changes as great as those which turn the nebulous masses of infinite space into great stars, whose light will shine on for countless ages after man has ceased to exist, or that which converts the sunshine and the dew into the flowers that spangle the meadows or brighten the wayside.
Leaf by leaf the great book of nature was turned, and the story found to be marvellous beyond any conception of poet or romancer. To the common eye the surface of the earth, with its wide diversity of mountain, valley, ocean, and plain seemed wonderful enough, but the geologist looked deeper and found still more enchanting scenes. Like a magician of old he bade the earth lay aside her green veil of mystery, and claimed her secrets for his own.
He examined the rocks and found that the white cliffs of England were the products of living animals, and that the tiny shells, pieces of coral, fragments of sponges, and other fossils found in limestone or chalk rocks, indicated clearly the sources of formation, and pointed to a time when myriads of animals swarmed in the seas where now stand the long ranges of hills that give beauty to the land.
He looked at the great coal measures of Europe and America, and read in their records even more wonderful accounts of the time when the continents were clothed in verdure to the shores of the Arctic seas; imprinted in the dark layers of coal he saw the plume of the fern, great tree—ferns that towered like palm—trees, resembling species now found in tropical regions; while other forms, such as large cone—bearing trees resembling the pines, and trees of a type that has now disappeared from the earth, having the whole surface of the bark covered with leaves thickly set like scales, gave greater evidence of the abundant vegetation which gave grace and beauty to those far—off ages.
Then the zoölogist added his gifts of fossil animals, and it was found that the earth was full of the remains of ancient life, and that from the skeleton of the great mastodon, whose tread would trample down the trees of the forest, to the tiny leaf imprisoned in a crystal drop of amber, all could contribute to the story of the earth and make its meanings clearer.
But, while geologist and zoölogist combined their powers for the accumulation of innumerable facts, there was yet no theory perfect enough to account for the earth's formation, and to give the order of its successive stages.
And it was in this respect that geology became especially important to Lyell. He studied the different strata, the fossils, and the rocks that contained no fossils, earthquakes, volcanoes, the courses of rivers and glaciers, the fall of avalanches, and in fact all the phenomena connected with the changes going on in the earth, and it seemed to him that, as nature always works harmoniously and according to fixed laws, it might be possible to learn how all the changes that have taken place came to pass, and to formulate some law that should explain the workings of nature in this regard. Whle yet a student at Oxford a hint of the great system that he was to build up came to Lyell, but as this was in direct opposition to the popular theory of the history of the earth, he refrained from making it known until his studies and experience should have made him better able to pronounce upon such an important matter. With this in view he began to travel, visiting France, Germany, and Italy, and making the most accurate observations on everything that came in his way.
He studied the rocks of the Jura, the Alps, and the Valley of Chamouni, the glaciers of the Rhone, and the floods of the Valois, and in his descriptions of these places showed remarkable power both as a botanist and geologist.
When he returned from his journey he began geologizing through England, examining chalk beds, crystallized rocks, alluvial marsh lands, and clay pits, and from his indefatigable industry soon became known to all the leading geologists, who were glad to give to his powers of observation and generalization the tribute which they justly deserved.
In 1823 he was elected a secretary of the GeologicalSociety, being in his twenty—fourth year. In the same year he visited France again, and saw Cuvier and Humboldt, both of whom recognized in the young geologist a worthy student of science. For several years after this Lyell's time was spent, partly in England and partly on the Continent, studying volcanic and glacial action, and preparing his work on geology which appeared in 1830.
Up to this time there had been a wide diversity of opinion among geologists as to the causes of the changes in the earth's surface. About the middle of the seventeenth century, Steno, a Danish geologist, gave to the world his explanation of fossils, claiming that they were the mineralized remains of animals, and said that the animals now in existence could only be properly studied by comparing them with the fossil remains of other ages. This was a step far in advance of the time when it was claimed that the shells and fossils found in mountains remote from the sea were made by the stars, or produced by some trick of nature, and the suggestion to study the past from the present was made in the true scientific spirit.
A century later, Hutton, a Scottish geologist, whose love for the chemistry had led to the study of geology, made some interesting observations on the changes which water will produce on the hardest rocks, and gave it as his belief that all the former changes in the earth's surface were due to the same agents that are now at work. He claimed that the strata which composed the earth at present were once under the sea, and said that the ruins of an older world were visible in the present structure of our planet, and that the same forces were now at work destroying the hardest rocks and carrying them to the sea, where they become again altered by volcanic heat, and that thus there was a constant change going on all the time in which nothing was lost, but everything gradually transformed.
At that time the popular theory of the changes in the earth's surface was quite opposed to the views of Hutton; nearly all scientists taught that all the changes that had taken place in the earth's crust had been caused by great and sudden convulsions, such as earthquakes, volcanic eruptions, floods, upheavals and depressions of the land and similar phenomena, which clearly indicated that nature acted spasmodically, and the earth had reached its present condition through the action of forces very different from those now in operation.
This view would, of course, preclude the idea that nature acted in a uniform or constant way, and supposed all her laws to be subject to violent changes.
Hutton's theory was recieved with little favor by the public, who saw in it a disposition to ignore the Biblical account of the creation, and the author recieved a storm of abuse from critics who thought that any inquiry into the origin of the universe was an act of impiety. But to all his opposers Hutton only replied that the laws of nature were immutable, and that the forces which governed the changes on the earth were as unalterable as those which kept the planets in their courses, and held the reins of life and death.
Hutton's theory was far in advance of his age, and was not generally accepted even by the most liberal men of science, but it is interesting to know that it became Lyell's work to elaborate the same idea, and to so strengthen it with indubitable proofs as to make its acceptance a necessity.
Contemporarily with Hutton lived the English geologist, William Smith, whose good fortune it was to carry geology a step farther than it had yet reached.
The different strata of layers found in rocks had heretofore attracted the attention of geologists very slightly, and the beds of different materials which lay one over the other in pits, and rock quarries were little regarded. Thery were known to exist, just as the beds, or strata of mud, gravel, and sand were known to alternate in the mouth of a river, but they were hardly recognized as of more importance than that given by the old botanists to the different colors of the rose, or the varied tints of the lily.
But Smith studied the strata of all the rocks that he saw, and was able, from his accurate observations and logical reasoning, to deduce a theory of the earth's formation in which the strata formed a prominent part.
Two important discoveries were made by this geologist : first, that there is a regular order of succession of the strata, or beds, which proves them to have been formed at different times, and that in every case the beds at the bottom are the oldest; also that this same order of succession may be found all over the world; and so sure was Smith of the truth of this theory that even at the time of its first conception he guessed correctly the nature of some hills he saw in a distance by their relative position in regard to certain rocks in the county through which he was passing. The second discovery was of equal importance, namely, that each stratum contained fossils differing from those fossils in other layers, and that knowing the fossils one could determine the strata from which they were taken. From these two discoveries Smith deduced a general law which he summed up as follows : The same strata are always found in the same order of succession, and contain the same peculiar fossils.
Lyell's "Principles of Geology," which was pupblished nine years before the death of Smith, incorporated the views of all those geologists who had striven to prove that nature works in a uniform manner, and the author announced as the foundation of his theory the belief that the past could only be studied from the present.
Lyell's studies, travels, experiments, and observations had all led him to the same conclusions, that in nature there is no life or death, but only change; and that the same agents which produced the great changes on the earth's crust are at work now, although they work so slowly that the effects are almost imperceptible.
Murchison, a distinguished contemporary of Lyell, taught that the mountains, and hill, and valleys had been created by great and violent convulsions of nature. This was called the convulsionist theory and had many adherents, who explained every change by saying it was the result of some great catastrophe.
But Lyell had the book of nature with a clearer eye, and his study had led him to a belief more in harmony with the known laws of the universe. He taught that those subtle alchemists, the rain, and the frost, and the snow, the rivers and the glaciers, carried on their silent work of transformation in the remote ages as surely and as steadily as they labor now; that the river which comes down from the mountain cutting its way slowly through the solid rock till the path has deepened into a trench, and the trench widened into a ravine, and the ravine become a valley, is but a type of the action of all the rivers that have flowed since time began; and that the rain and frost which splintered the mountain crest into peak and pinnacle, and carved out crag and cliff from its rocky sides are still carrying on the work begun when first the mountains were upheaved by the great forces working in the interior of the earth, and never to cease till all the ages of the future have passed away.
Lyell took the minerals and rocks of the earth and placed them one by one in their proper places till the great book of the earth's history could be read from beginning to end, and all its text and pictures rendered so clear that even the most ignorant could understand it, and know that the child who stands by the mountain rill watching the strong current sweep along the shining pebbles is reading the secret by which the great rocks were formed; and that the violet which drifts upon the surface of the meadow brook till it is caught and tangled among the debris at its outlet is but a type of those great deposits which it took thousands of years to harden into imperishable forms of beauty : while the tiny sea—shell which he picks up along the shore tells the same wonderful story of those bygone ages when all the teeming life of the animal and vegetable worlds had not yet turned to stone.
The fact that the different strata could be recognized by their fossils was made by Lyell the basis of the law of succession of life upon the globe, and from this time geologists began to speak of the different ages of the world in reference to the life of plants and animals upon it; those rocks in which few fossils are found belonging to one age, those which contain fossils resembling living species, another age, and so on, until the present was bound to the past with the strongest links, and the succession of life was proven with the same ease that one might demonstrate a law of mathematics.
Although the "Principles of Geology" met with severe criticism from those who fancied that they saw in it proof that the author wished to inculcate views different from those taught by the Church as to the origin of the world, it grew steadily in popular favor, and is the theory accepted at the present time. And Lyell's work later on showed the same spirit of progressive thought.
His travels in Europe and America only served to deepen his belief in his first impressions. Thirty years after the publication of the "Principles" he published his "Antiquity of Man," in which he claimed that the human race was many thousands of years older than had been supposed, a theory which later researches have all strengthened, while his observations on the great ice age an equal value for later geologists.