Chapter XIII: The Guadaloupe Human Fossil 159 (1)

THE

PUZZLE OF LIFE.

_THE FRAMEWORK OF THE PUZZLE._

You must often have looked with wondering eyes at this World of ours, and asked yourselves questions about it. How did it come here? What is it made of? How old is it? All of them questions not to be answered without a great deal of thought and study, and even then not so perfectly as we should like. It is easy to say “It is here,” and “It is made of earth,” and “It surely must be old,” but that will not satisfy us. We want to know something more certain than this, if possible. We can see that a clock goes with wheels, but we are not very intelligent people if we do not want to find out what makes the clock go. One way of finding out is to pull things to pieces, but we cannot exactly do this with the World. We must think about it, and put together all the knowledge we can gain from the outside and inside, and from the other Worlds around us, which we can see, and when we have done this we may get something like answers to our questions.

How did it come here? But this is not quite the right way of asking the question, because the World is never for two moments together in the same place. It is travelling in a great circle round the Sun at the rate of more than sixty thousand miles an hour, and has been ever since it was formed. That is a wonderful arrangement by which all Worlds travel round some other World larger than themselves, in greater or less circles, and we do not know why it is, though we are certain that it is so. The Moon travels round us once in about every month, and we and the Moon together round the Sun once in every year.

Then again, other planets, with their moons, such as Jupiter, for instance, travel round the Sun in much larger circles than our World, and take many years to do the journey, while Venus, which is nearer the Sun than we are, travels in a much smaller circle, and takes less time. We do not perceive that we are moving so fast because everything we see is moving equally fast with us; but there is no doubt that we are spinning along at sixty thousand miles an hour.

If we ask an astronomer how our World came into existence, he will tell us that it is probably a mass separated from the Sun, that it was once red-hot, and that it slowly cooled down until animals and plants could live upon it. He will tell us besides, that he can see mountains and valleys in our Moon, and land and sea, snow and clouds, on the planet Mars, with his great telescopes. When he thinks about the planets and our own World, then he believes them to be pieces of some much larger World—perhaps the Sun—which now travel round the Sun and receive their light and heat from it. The World is made of what we call “earth,” and it is of this I mean to tell you now—how it was formed, what changes have taken place in it, what plants and animals have lived upon it, and what reasons there are for thinking that it is an exceedingly old place, with a long and interesting story to tell.

Little was known thirty or forty years ago by the most learned men about the age of our World, and it was thought that the human race had not lived here very long. It was indeed known that many large animals, whose huge bones have been found, must have lived before man came to inhabit the Earth, and that even far smaller creatures—such as fishes, and crabs, and insects, and shell-fish—most probably lived for many generations, and died and left their bones and shells in the soil long before the first man or the first tribes of men came to share the World with them. I hope to be able to tell you something of the strange and beautiful history of all these animals, and of man himself, and to show you what reasons there are now for thinking that the human race has inhabited this Earth for a very long time indeed, and how all this knowledge has been gained and put together piece by piece. It is something like the different parts of a puzzle-map, which might be scattered all over the house, and found at one time or another in different places, and at last made up altogether. Some parts of the puzzle have not been found yet certainly; but so many have been collected, and they fit into one another so well, that we can begin to see its real shape and size. It will perhaps be a very long time before some of the missing pieces are found; but in the meantime we can go on without them, and put the framework together, and no doubt in time we shall see what our puzzle, the history of life on the Earth, was like.

Before telling you what its parts are, I ought to say where many of them have been found, and how they are still being looked for. They are found _upon_ the ground, _under_ it, in caves, in rivers, and in the sea. Since railways have been in use a great many tunnels have been made, as well as very deep cuttings through hills, and some of these are several miles long. In this way we have come to know something of the Earth below the surface. Some of these tunnels are bored right through high hills and even mountains, and the cuttings are deep enough to hide high houses if they were put into them. While digging these the workmen have found many of the parts of our puzzle, which are the bones of animals, and fishes, and shells, and even smaller things—such as insects. These could not possibly have been put there by anyone, because they were many, many yards below the surface, and, until they were dug up, nobody imagined that they could be there. Many other things besides have been dug out of these places, but nearer the surface, such as weapons and tools made of flint, and stone, and bone, and metal, and pieces of rough crockery, and various ornaments, all of which must at some time or other have been made and used by people very like ourselves. In digging canals, too, the same kinds of things have been found, and some caves are almost filled up with them. We have other means, too, of knowing what is under the surface of the ground we walk upon. Many of the coal-mines are so deep that the Tower of London, or St. Paul’s Cathedral, or York Minster, or even the Pyramids of Egypt could be buried in them! In digging these the workmen have had to go through a great quantity of earth, sometimes chalk, sand, or gravel, or clay or limestone, layer upon layer, placed, like a pile of books of different kinds and different thicknesses, one upon the other, until they have come to the coal. In these different layers of earth parts of the puzzle have been found, and we shall see by-and-by what parts have been found in the coal itself. Then again, when deep mines are made to get the metals, iron and gold and silver, these layers of earth have to be dug through; and when the beautiful kinds of stone, like marble and limestone, are wanted, they must be dug out of the sides of the hills, and in doing this still more pieces of the puzzle come to hand. But there are other places where Nature herself seems to have shown us some of them without the trouble of searching for them. In many parts of the World, by the sea, and on the banks of rivers, there are cliffs hundreds of feet high, like the chalk cliffs at Dover and Ramsgate, and the sandy cliffs at Folkestone and on the south coast of Devonshire. These cliffs have been cut into by the sea very gradually, and a kind of wall has been left, and from the sides of the cliffs great numbers of the pieces of the puzzle, bones, shells, &c., have been collected and taken away to museums. But the little we can do with our mines and railway tunnels is nothing in comparison with the work of Nature. In some of the great mountain chains—the Andes, the Himalayas, and the Alps, for instance—parts of the sides of mountains have fallen down, and rents many miles long have been left, showing what had been buried there in the different kinds of soil; and where rivers have cut deep, narrow channels through the earth, like the Cañons of Colorado, these natural miners have turned out more of the parts of “the puzzle of life” than we can with all our labour.

It will not be easy at first to understand all the wonders I have to show you, but, when we get further on, you will see them one by one, and there will be very little difficulty. You know now where these things are to be found: principally in the ground you walk upon, without knowing all there is beneath you. The creatures here are much more wonderful than any of the monsters of fairy tale or fable, because the works of God are greater than the imagination of men who have invented the stories of flying dragons and griffins, and trees which grew up into the skies; but I cannot help thinking that this imagination shows what men thought _might_ once have been, and we shall see that “truth is stranger than fiction.” Creatures really did live on this Earth of such strange shapes and great size that the imaginations of those who wrote the fairy tales did not exaggerate much; and, though we know that no flying serpents or immense birds like the Roc are living now, and that there is no beanstalk which grows up into the sky while we are asleep, we shall see that there were lizards as large as whales, and birds taller than elephants, and great sloths stronger than the rhinoceros or hippopotamus, and ferns as high as oak trees, and mosses as large as gooseberry bushes; and that perhaps these animals and plants grew much faster than they do now, and that their dead bodies form a very large part of the earth of our World. This is not imagination, and when you go to a museum you can see all these wonders for yourselves, just as they were taken out of the earth; but of course the bones only of the animals are there. The flesh has long since gone away, and some of the stalks and fronds (leaves) only of the ferns remain to show us how large they must have been when they were alive and growing.

It will be necessary to use a few scientific names, most of which are borrowed from the Greek and Latin languages, but I will explain the meaning of them all, so that they will be easily remembered. First of all, then, the pieces of the puzzle are called _fossils_, and the name comes from a Latin word meaning “dug out;” because they have been dug out of the ground either by man in making railways and mines, or by Nature in the many ways in which she works by cutting down cliffs and scooping out valleys. These fossils are bones of animals and fishes, the skins, shells, and wings of insects, and the stalks and leaves of plants, some of which have lain so very long in the ground that they have become as hard and heavy as stone. But the shape of them always remains, and the moment you look at them you see that they once belonged to living creatures.

I shall give you pictures of some of these fossils; and no doubt you will be able to find some like them in the chalk and sands of the seaside—beautiful shells and bones of fishes. You may pick these out of the cliffs, and then go to the pools of salt water left among the rocks by the ebbing tide, and compare your fossils with the living shell-fish, and see how nearly those inhabitants of the ancient oceans resemble the creatures we find now, sporting in the water, just as these fossils did when the sand and chalk cliffs were under the sea. Of course all the bright colours are gone from the fossils, for the colour of animals fades away soon after they die, and the flesh does not last long; but the hard parts—the bones and shells—are not easily destroyed, because they are made of the same material as rocks. And when we look at the fossil plants we see the same thing. The colours of the green stems and leaves have quite faded, but the delicate shapes of the leaves and branches, and the grain of the wood, can still be seen, and you will have no doubt that they once lived and bore flowers and fruit, and died, as plants are living and dying every day.

You have got so far now that you know what fossils are, and where they may be found. You know that they are the small and large pieces of the “puzzle of life”—of all sorts of different shapes and sizes—and you know that they are scattered about the Earth, deep down in coal-mines, on the tops of mountains, at the bottoms of rivers, in deep caves, and under the sea. The patience and industry of clever men have been well spent in gathering together all they can find, and arranging them in museums for our instruction, and making a history of them which is more wonderful than the Arabian Nights, and more beautiful because it is all _true_. And, though you may think it strange that I promise to show you creatures more marvellous than those of the fairy tales, I shall keep that promise faithfully. We shall find no Genii with wonderful lamps and magic rings, because they never really lived, though it gave us much pleasure and amusement to read about them; but we shall see what God, the greatest Genius of all, has done by means of His magicians—the laws of Nature. These magicians have built up high mountains and dug out valleys, and sent mighty rivers sweeping down to the sea, and even filled up oceans with sand and chalk, and buried ancient forests deep down under sea and land. They worked with fire, and air, and water; not quickly, but with such strength that nothing could resist them, and they gradually moulded the Earth into the beautiful thing it is, so that

In contemplation of created things,
By steps we may ascend to God.—_Milton._

But, lovely as the Earth is, we should not perhaps have thought so much of it if there had been nothing to discover. We see that it has been prepared for us an immensely long time ago; and when we know a little, we want to search further and find out what the whole plan of Creation is, so far as we can. You will be surprised when you know how many signs of past life there are around you—many more than you can see with the eye. The Earth is one great burying-place of creatures which have passed away. You are walking over their dead and fossil bodies at almost every step. They are built into the walls of our houses, and there are millions of them in some of the commonest stones of the pavement. Those round, smooth pebbles, called flint stones, which we pick out of the gravel walks, were once partly such soft tender things as sponges; but time has hardened them, and they have been rolled together in seas and rivers by the always moving water until they have become quite different to look at from the rough blue flints they were when they were washed out of the chalk beds. When you are walking along the sands of some seacoasts, you are treading on little specks of these small flints which have been ground down fine in that great mill, the ocean. The sponges, then, did some part in the building up of the Earth. The very chalk you draw with is composed of the shells of sea-animals. Your slates and slate pencils were once a fine mud at the bottom of the sea, since become so hard that it is used for covering the roofs of our houses, and in this mud lived myriads of small shell-fish which have sometimes left their frail houses in the slate beds to tell us how they were made. That slate is the hardened mud of an old sea bottom, there is no doubt at all.

There are many other things in common use which show us the life that was.

Perhaps you did not know that coals are _compressed plants_, and that we are now burning the vegetation of the past time! But these will be described in their right places by-and-by, and you will see how certain it is that some of the commonest things we use were living creatures and graceful plants.

Here is “the framework” of the puzzle, and I think you will agree with me that we shall have pleasure in putting it together with all the queerly-shaped pieces we shall find in the following chapters. We have fossil plants to show us what grew upon the Earth, fossil bones to tell us what animals lived here, and thousands of different kinds of fossil shells and fishes to show us that the seas in the long past time were crowded with life; and besides, though there are no written histories of the men whom we shall read about, they, too, have left many things which they used in the caves where they lived and in their graves, to make us feel certain that they were some of the oldest people that ever lived. With all these things to help us, it will be strange if we cannot make out a great deal of the history of life upon our Earth.

_THE GEOLOGICAL PART._

You will have learned from other books something about the size and shape of our World: for instance, that it is a great round body, or rather more like an orange, a little flatter one way than the other, and about 8,000 miles through, from one side to the other, and that it turns round once in every twenty-four hours; but I have only to tell you now what it is made of. The material is called rock, earth, or soil; and there are many kinds of it, such as granite, gravel, clay, sand, chalk, mud, and so on; and we shall see that many of these different soils contain different fossils.

It is supposed that a very long time passed while these were being laid one upon another, and before many plants or animals lived here, and there are good reasons for thinking that underneath these soils the Earth is very hot, perhaps in a melting state, because we know that volcanoes like Vesuvius and Ætna throw out flame and smoke and lava, which is melted earth and rock; and that this lava has run down the sides of the mountains for miles, in a great stream of liquid material, and covered up and destroyed whole villages and towns. You have heard of earthquakes, when the ground shakes and cracks, and houses are thrown down, as they have often been in Spain, Italy, and South America. This convinces us that the inside of the earth must be very different from the outside. Two or three years ago Mount Vesuvius was boiling up, and the people of Naples feared that it would throw out some of the terrible lava and red-hot cinders, and burn up their vineyards and perhaps injure their city; and during the last two or three years many people have been killed by earthquakes in South America. These things seldom happen in the North of Europe, and when they do they are only slightly felt, and people are not killed, neither are houses thrown down. Still, this shows that there must be some great force underneath us, and very much heat. We see nothing of this when we look upon the green fields, and we should scarcely think it possible if there were not histories about these eruptions, as they are called. But when I tell you that I have felt the Earth tremble, and seen fire rushing out from the top of a high mountain whose sides were covered with snow, you will understand how real it is—though it may seem so strange.

People at one time liked to fancy that powerful spirits lived in volcanoes and made them their workshops: but we know better now.

Well, the interior of the Earth is evidently very different from the part we live upon; and it is the outside we have to think about now, which would be dreadfully cold if the sun did not shine upon it, though the inside is so hot.

I have called this “the Geological Part,” and the name Geological comes from two Greek words meaning “a talk about the earth;” but now you know it in its English dress it will be easy to recollect it. Geology is then the study of the many kinds of rocks and fossils which makeup our World, but we must know something of the way in which they are placed.

You may have noticed, if you have made many journeys to different parts of England or Wales, that the rocks or soils are very different in various places. Sometimes we find numerous chalk-pits, as in parts of Kent, or Sussex; if we go into Devonshire we may notice the very red colour of the soil and of the cliffs, especially near Sidmouth, Dawlish, and Teignmouth; in North Wales we find great quarries and hills of slate; while around London we see a great deal of clay used for making bricks, and called the London clay, as well as many pits in gravel so useful for making paths and mending roads, and in Kent and Sussex chalk cliffs and hills are common.

Now after studying these various rocks all over our country, we find that there is a certain regular order in which they are found; some have been made a long time before others, and while most kinds contain some fossils, those found in the oldest rocks are much less like the living plants and animals than the fossils we find in the newer rocks.

But you will want to know how it is that we can tell that one rock is older than another, when both appear at the surface of the earth. It would take a long time to make sure of this for ourselves, but it will be enough to say that the various cliffs, quarries, and railway-cuttings often show one kind of rock resting upon another, and these always occur in a certain order. Thus we never find the Chalk resting on the London Clay, but we constantly find the London Clay resting on the Chalk. And this is proved in another way, by deep well-borings. Underneath London many wells have been carried down right through the London Clay, and if only continued deep enough they always reach the Chalk. In the same way, the order of the other rocks has been ascertained in different parts of the country, by examining all the pits and quarries, and cliffs and cuttings, with the help of what knowledge can be obtained from deep mines and wells.

You will now begin to wonder why the older rocks should appear at the surface. I have told you about earthquakes, and you will find that many dreadful earthquakes must in former times have ravaged our country. The reason why the old rocks come to the surface is because they have been lifted up sometimes violently, but more often very slowly. And the newer rocks which formerly rested on them have very often been quite washed away, either by the sea or by rivers and little streams which formerly acted upon them.

Suppose then we take six books, some thick and some thin, and pile them up together on the table, the lowest being a good thick one. The lowest we will call granite, the next slate, the third sandstone, the fourth coal, the fifth chalk, and the sixth the London clay. These will represent some of the principal kinds of earths, and you can fancy many more with other names coming between them; but the London clay can never be below the granite nor the chalk below the coal, for the great coal beds were formed long before the chalk and clay. They generally come in much the same order as we have named them, hard rocks like granite at the bottom, and softer earths, like sandstone, chalk and clay, a long way above them. But we do not always find all these earths in one place even if we dig ever so deeply, though the granite would always be found at the bottom if we went deep enough.

Sometimes the granite and other old rocks have been pushed through the upper layers by some great force, and have broken them and risen above them in magnificent mountain chains, like those of the Andes in South, and the Rocky Mountains in North America, the Wicklow Mountains in Ireland, the Grampians in Scotland, and the Cornish mountains in England. We can easily suppose that the lowest of our books (the granite book) has been pushed upwards by some great force from below, and parts of it broken through the others, and raised high above them; and this is what has actually been done with real rocks. And as this kind of upheaval has taken place at different periods of the earths history, we find that granites have come to the surface at different times.

When the layers are thus broken through they are often tilted up on end and tumbled about in confusion. But where there has been no disturbance like this, they generally rest evenly upon one another in their proper order.

Granite, and rocks of the same kind, are not in the least like chalk, or clay, or even sandstone, and when once you have seen any of these you will not be likely to mistake it for the others. Granite is excessively hard, and has a beautiful appearance when polished, with a number of brilliant white and some dark specks in it. It is used for paving the streets of towns, for which purpose it is cut into oblong blocks, and for the pillars of fine buildings. Sometimes it is dark brown, sometimes reddish, but generally a bluish grey. This rock is composed of a great quantity of crystals, and for this reason it is thought it must have been melted at one time by intense heat in the earth, and afterwards slowly cooled. Chalk is very different, and sandstone, though it is also hard, not in the least like granite.

HOW THE ROCKS WERE FORMED.

What I have just said is about all that we know of the formation of the oldest and hardest granite rocks: but there is something going on now which confirms the belief that the materials of which they are made were melted together by a greater heat than we can make in our furnaces for melting iron; for I should tell you that it is easier to melt iron and copper than granite rocks. Volcanoes often throw out melted earths which when cooled appear to be made of much the same materials as these granites.

SANDSTONE.

But we know more of the manner of the formation of sandstone. This rock is composed of rounded grains of sand just like that we find upon the sea shore. If you take a handful of this sand and squeeze it tightly, it will keep together a little while. Now suppose a quantity of this sand was pressed by a very great weight—the weight of a large hill for instance—after many years the grains would stick firmly together, and become a sort of stone. It is in this way the sandstones must have been formed, and perhaps heat helped the work, though not so great a heat as melted the granite. The sand, after it had been washed upon the sea shore, became gradually covered with other earths hundreds of feet thick, and the immense weight above it pressed it into stone: but you may imagine how very long a time it took to do this. Sandstones are used for building, but they do not last very long; the frost makes little cracks in them and they soon crumble away to the grains of sand of which they were made. Several fossils are found in some of these sandstones, which have been formed at many different periods of the earth’s history.

CHALK.

You have seen those high cliffs of chalk along the south coast of England, perhaps, and you have wondered what that beautiful white earth was, and how it came there. It is found in many parts of the world, and the south and south-east of England are to a great extent composed of it. The material is called by chemists carbonate of lime. It is almost entirely made up of minute shells called _foraminifera_, from two Latin words which mean that there are many openings or chambers in their shells, and there are many beautiful fossils called _ammonites_ imbedded in the chalk. These are shell-fish, two or three inches, and sometimes a foot across, and their shape is very like that of the young leaves of the common fern before it has opened in the spring.

Millions of these tiny foraminifera are living now in parts of the Atlantic and Pacific oceans, and when they die their shells sink to the bottom and form a greyish mud, something like chalk.

When H.M.S. “Challenger” was sent out in the year 1873, to find out what was at the bottom of the deepest seas of the World, great interest was felt in the expedition, because we were sure that we should learn something about the manner in which some of the rocks were formed.

We knew that the whole of the beds of the present seas must be receiving the washings of the rivers and the bodies of many fishes and animals, and that the rocks of the future must be forming down there by these accumulations. Long lines were let down from the ship with a dredge at the end, and thus parts of the bottom of the sea were brought up and carefully examined. It was found that the washings, stones, clay, and mud of the land were carried hundreds of miles out to sea, and laid upon the bottom. But in the deeper parts, where the Alps would be almost covered—there was a fine grey mud composed almost entirely of the shells of the little foraminifera, and this, no doubt, is the chalk of future times, or perhaps limestone of a harder kind. Deeper, too, than where this grey mud is found, there is a reddish mud, exceedingly fine and soft. We cannot exactly say yet whether this is formed from the remains of shell-fish; but it is, at all events, very like the clay of the land, and in some future time will most likely become like that stiff mud we know so well. So that even the materials for bricks are being made now, and perhaps when all those hundreds of islands scattered about the Pacific Ocean are joined into one great Continent, this red mud will be raised and made use of for building the houses of new peoples and nations.

When we see this going on now, of course it is very easy to conclude that the chalk, a great deal of which is above the sea now, must have been formed in the same way at the bottom of an ancient ocean, and afterwards raised by the same kind of upward force which made the granite break through other earths.

If we did not know that the same cause was at work now, and that the same kinds of shell-fish were living and laying down new beds of chalk under the sea, we should not know how to account for the quantities of chalk in the world. For innumerable ages these little creatures have thus been paving the floor of the ocean with their dead bodies, and you may suppose that countless millions of them must have lived and died! In some of the chalks the shells of the foraminifera can be quite distinctly seen with a microscope, and when these are compared with the shells of living ones, they are seen to be almost exactly alike. Next time you pass through one of the railway cuttings through the chalk in going to Brighton, or Ramsgate, or Dover, remember that those high cliffs were built up by these Liliputian giants under the sea, and you may think of the chalk as “foraminifera earth”.

COAL.

You see this black shining substance almost every day, and you know it is dug up from very deep pits where the poor miners are often killed by explosions of gas escaping from it. But it is as well to know what it is and how it comes to be so useful to us. In the language of chemistry it is called “carbon”, and a great writer has given it the poetical name of “compressed sunlight”. But you will ask how sunlight could possibly get into a deep mine, and how it could be compressed there. You will see that the explanation is really quite simple by-and-by. This coal was once above ground, and was a splendid forest of waving palm-trees, and ferns, and gigantic mosses, as you will see by the pictures of the fossils of them.

Many of the animals and plants of past times were giants compared to those living now, of the same species or kind, and many of the plants of the present time are dwarfs to those of the same kind which formed the coal beds. Many generations of trees must have grown and died, and others must have sprung up, and so on, until beds of them, some ten, others twenty, or even thirty feet thick, were formed. Here, buried in the coal, are the stems, leaves, bark, roots, fruit, and seeds of these trees, and we can have no doubt that almost the whole of the coal is composed of them. You must not expect to find the shapes of these in every piece of coal you may happen to look at, because most of it has been greatly changed by the great weight and pressure upon it, and the length of time: but it is certainly all the same substance—wood turned into coal. The fossil plants of the coal are of course entirely black, but there is no mistake about their having once been living plants.

You will ask perhaps how the coal came to be buried so deep. It is not so always, being sometimes at the surface. But just as the granite has been pushed up through the other rocks, so has the coal in some places been uplifted and in others has sunk down. It was often covered up by other earths to a great depth, after the trees which composed it had died; but where it is now at the surface these newer earths have been afterwards worn away. When the sun shone upon these coal trees they took its warmth and light into their stems and leaves, for they could not live without, and this made them grow so fast and become so large that it is not untrue to call coal “compressed sunlight.” Charcoal is in some respects so like coal that it would seem to you at once that they were probably the same material. Charcoal is simply burnt wood, and when the coal forests had died down, and when these beds sank down beneath other layers the pressure and heat together turned the wood and leaves into a hard mass like charcoal in colour, but heavier and more solid, and just enough of the stems and leaves have been left to enable us to know with certainty that coal was once wood.

We light our fires now and drive our steam-engines with the heat of the sun which shone upon the coal forests, and has been stored up for many thousands of years in the Earth, to be brought out once more to give us light and warmth.

CLAY AND MUD.

While the ancient forests were growing up to form the coal beds, and the foraminifera were slowly building up the chalk, as I have explained, the Earth was covered with water in some places which are now dry land, and the sea now flows over parts of the World which were once the habitations of plants and animals. These great changes have left their marks upon many a mountain side, and many an old river or sea bed has become filled up. A map of Europe during the chalk period would show that the places where Paris, London, Copenhagen, and Berlin now are were then under the ocean; but since then these places have been lifted up, and mud, clay, and gravel swept over the chalk in many places by the action of new rivers and seas. Water, you perceive, has had a great deal to do with these changes, and indeed it is one of Nature’s most powerful tools, for it can wash down rocks and cliffs and cut its way in rivers for thousands of miles over the Earth’s surface. It carries down mud, and clay, and gravel, and this soil, which has been named alluvium, is one of the most interesting of all to us, because it contains the bones of the immense animals we shall talk about presently, as well as those of the oldest races of men with their weapons and ornaments.

The mud age, and we are in the mud and gravel age now, belongs to what is called the Tertiary period, and we shall see that this age has lasted a very long time already, so long that though it is still going on, the most extraordinary animals have lived and died, and not one of them is now left alive. Still the same washing and cutting of water is going on which buried their bones in swamps, and bogs, and river caves, and may perhaps carry away some of the bones of us who are living now, to be found ages afterwards by future generations who will read our history in these silent witnesses, as we read the history of the tree ferns and foraminifera in the coal and the chalk.

The present age of the World’s history is the Mud age, or, as we shall call it in future, the Tertiary period, and I think you will agree with me when I come to describe it, that it contains the most interesting of all the pieces of “the puzzle of life.”

The earth of the Tertiary period is very different from a great many of the older earths. Clay, mud, and gravel are the washings only of the older rocks, the fine particles which have been worn off from them by frost and water and carried down by rivers and left in large beds, and sometimes they have a good deal of decayed wood and weeds mixed with them. Here are found the bones of the great animals which were so much larger and stronger than those of the same kind living now, or any that lived before them.

UPHEAVAL AND DEPRESSION.

These two words are so often used in books on geology that we shall not be able to get on without knowing their meaning. We have seen that the rocks have been formed in a certain way—some by heat, some by water, and some by dead forests—and that they lie over one another in pretty regular order. But this order has sometimes been disturbed and the layers have been tumbled about among one another very much. In some places the older rocks, such as granite, slate, and sandstone, have been pushed up through those above, and in others the coal has sunk down and been covered with thick layers of chalk, sand, and mud. When the force below pushes a layer up through the others it is called _upheaval_, and when a layer sinks down it is called _depression_, or _subsidence_. Both these actions are going on now in different parts of the Earth. A great part of Sweden, Norway, and Denmark, of Spitzbergen, Siberia, and the north of America, is being slowly raised higher above the sea, as we know by the height their old sea beaches now are above the water; while part of the shore of America opposite to Europe and also the south of Greenland is slowly sinking down, as we know by the remains of land animals and trees which are now covered by the tide; and at many places on the coast of India this subsidence is also going on. Nearer home, too, there is an example of it in the island of Guernsey. All round the coast of this island, like that of Jersey, are found tree trunks and other remains of old forest land beneath the water. Old histories refer to this as dry land; and if a map of it made in 1406 is correct, this land must have sunk about 150 feet since that time.

Thus we can see, even at the present time, the very same changes which have worked upon our Earth for innumerable ages. It is now easy to understand how the forests which must have grown above in the air have, after a long time, sunk down to a great depth, and been turned into coal, and covered with the sediment, sand, gravel, and chalk from the seas which afterwards flowed over the places where they grew.

Sometimes the rocks by the sea shore are cut into terraces or steps by the constant wear of the water, and when we see these water marks far above the present level of the sea we know that the land must have been lifted up gradually above the sea. There are many such terraces in Norway. To prove whether this is so marks have been cut upon rocks at a measured height above the sea, and after some years these marks have been noticed to have been raised much above the water by the “upheaval” of the earth at that place.

Generally this change of level has taken place gradually, and the greatest work in moving the layers of earth and displacing them has been very slow. But in some places violent and sudden shocks have happened, tearing up the rocks and piling them up in heaps; and now and then islands have suddenly appeared in the sea and vanished out of sight completely in a short time. Islands have thus come up in the Mediterranean Sea within the memory of man. In the year 1831 the island of Julia suddenly appeared near the coast of Sicily, and since the year 186 B.C. no less than three islands have started up in the bay of the island of Santorin. In this century islands have appeared among the Azores, the Indian Archipelago, the Philippines, the Moluccas, and on the coast of Kamtschatka and other places. Some of these have appeared suddenly, others slowly, and they no doubt have been raised by a great force from below.

You will see now how easy it is to account for the changes of the places of the layers of rock. The same thing is going on now which has been going on throughout all time, only perhaps with more energy formerly than now, making mountains, islands, and continents, raising up a large tract of land in one place and sinking an island or a sea shore in another.

These changes have been of great use to us too. Suppose all England had been covered with coal or slate, we should not have been able to grow anything! As it is we have sand and gravel in one county, chalk in another, slate or granite in another, and coal down below in several, and we can grow a great variety of plants on all these different soils. We have to thank “upheaval” and “depression” for this. The force which is always working below us has turned up the different soils like a gigantic plough, and brought some to the top and covered others, so that instead of having to dig down deeper than ever we have yet, we have only to go from one county to another to find the different rocks. We know that we could not get at the coal in Sussex without going down an unknown depth through the chalk and other earths, but we dig for it in the North of England, where we know its depth below the surface.

I will try now to give you some idea of the way in which the rocks come in their order, or the succession of formations as geologists call it. If we started to walk from Wales to London the rocks we should pass over would be—slate and flagstones in Wales, and going on towards London, limestone, old red sandstone, more limestones, coal beds, new red sandstone, oolite, greensand, chalk, and last London clay. We might not always find each of these near the surface, but they would be found to be the principal rocks on a line between Wales and London, the oldest being in Wales and the newest or most recent as we get nearer London. That word “oolite” which I used comes from two Greek words meaning “roe” and “stone,” because the rock is composed of little rounded grains of a chalky substance shaped like the hard roe of a fish, or like sago before it is cooked.

If you look at the following table you will see how the principal rocks are placed one upon the other, beginning at the lowest or oldest at the bottom and going up to the newest at the top of the table, and on the right hand side I have written the names of the principal fossils which each kind of earth contains.

TABLE OF THE SUCCESSION OF FORMATIONS.

TERTIARY, or Upper Rocks

Peat bogs and caves Fossil Man, with stone implements,
River-mud and brickearth, &c., mammoth,
gravels, and hippopotamus, rhinoceros,
boulder clay (alluvium) Irish stag, cave lion,
&c.
Crag of Eastern Counties Numerous shell-fish, mastodon
London clay, &c. Turtles, crocodiles, shell-fish

SECONDARY, or Middle Rocks

Cretaceous

Chalk (with and without Foraminifera, &c., sponges,
flints) corals, sea-urchins, shell-fish
Greensand and gault (Belemnites, Ammonites,
Wealden clay, &c. &c.), fishes

Oolites

Portland stone
Kimmeridge clay
Coral rag Immense reptiles, the Ichthyosaurus,
Oxford clay Plesiosaurus,
Cornbrash and forest Megalosaurus, Pterodactyl,
marble &c.
Great oolite
Fullers’ earth Animals allied to the opossum
Lower oolite and kangaroo

Lias clay and limestone Cycads and other plants
New red marl and
sandstone

PRIMARY, or Lower Rocks

Coal Ferns, club-mosses, a few
Millstone grit firs, calamites, &c., in
Mountain limestone great abundance
Old red sandstone Numerous corals, shell-fish,
Silurian limestones and trilobites, fishes, &c.
slates
Cambrian slates The Laurentian rocks contain
Laurentian rocks the oldest known
fossil, the Eozöon (or
“life-dawn animal”)

IGNEOUS, or Volcanic Rocks

Greenstone, basalt Of various ages (no fossils)
Porphyry
Granite, &c.

If you read this table upwards from the bottom you will notice that life began in a very small way with Eozöon (the “life-dawn animal”), that fishes appeared afterwards, that the wonderful forests of the coal period then grew and were covered up by other rocks and pressed into solid coal, that numbers of great crocodile-like animals lived all through the oolite time, how the deep wide beds of chalk were laid down by humble foraminifera, and when we get to the recent newest beds of gravel, mud, sand, clay, &c., the sweepings by water of the older rocks ground down by ages of wear and tear, we have the mammoth, mastodon, megatherium, and other great vegetable eaters, and lastly Man himself with his simple weapons of stone, bone, and horn—our early forefathers.

You must always keep in mind that the greatest of these changes have taken place very slowly. Mountains have been raised, and whole continents have been sunk by movements so slow that if the hands of a clock went only once round the dial in a year the hand would go faster than these mountains have risen or the continents sunk. Almost always whenever there has been sudden and _violent_ action it has been near volcanoes or during earthquakes; but these things, terrible as they are to the people living near, disturb only a very small part of the surface, and such violence neither buried the coal beds nor raised the slate hills of Wales. Many of the small effects of the internal force of the earth have been sudden and violent, but the greatest and grandest have been slower than anything we can imagine.

If this had not been so, we should not find fossil shells just as they sank quietly to the bottom of ancient seas, quite undisturbed. We should not find delicate ferns and insects with all their breakable parts perfectly preserved, and as lightly laid as if you had put them away carefully in a cabinet upon cotton wool. Yet many of these have sunk down hundreds of feet below the open air where they _must_ have lived. We find the ripple marks of the waves on old sandstones, and even the prints of the feet of birds and animals as they walked upon that rock when it was soft sand, and the little pits made by rain-drops on the moist earth. All this speaks of stillness, and gentle movement, no violence. So slowly and softly have these rocks settled down, that we can read in them the history of the life that was. But if there had been any sudden and rough movement all these fossils might have been broken up and we should have had nothing but fragments, and the “puzzle of life” could never have been put together. Nature’s forces are immense, but they work slowly, irresistibly, and majestically.

THE ICE AGE.

We have seen now what the principal rocks are made of and the way in which their places have been changed by upheaval and depression. Water, as we know, has been at work and has done great things in _all_ ages of the World’s history. I have called it “one of Nature’s most powerful tools,” and when we look at the quantity of chalk alone that there is in the world, and remember that this was all laid down in water, and perhaps a great part of its lime carried down by rivers to the seas where it settled to the bottom, after the corals and small shell-fish had worked it into their bodies, we are right in thinking water a great Magician indeed. Why, even so small a river as the Thames carries down to the sea every year as much dissolved earth as would make a good large hill; and what must such rivers as the Nile, the Amazon, the Mississippi, and the great Chinese rivers do! There must have been gigantic rivers, too, in the old times, or else it would have been impossible that the deep sandstone and slate beds could have been formed; for these are all laid down by the washing away of earth in water.