Part 11

You must know that certain sorts of shells live in deep water, and certain in shallow. You may prove this to yourselves, on a small scale, whenever you go to the seaside. You will find that the shell which crawl on the rocks about high-water mark are different from those which you find at low-tide mark; and those again different from the shells which are brought up by the oyster-dredgers from the sea outside. Now, the lower part of the clay, near here, contains shallow-water shells: but if you went forty miles to the eastward, you would find in the corresponding lower beds of the clay, deep- water shells, and far above them, shallow-water shells such as you find here: a fact which shows plainly that this end of the clay sea was shallowest, and therefore first filled up.

But again--and this is a very curious fact--between the time of the Plastic clays and sands, with their oyster-beds and black pebbles, and that of the London clay, great changes had taken place. The Plastic clay and sands were deposited during a period of earthquake, of upheaval and subsidence of ancient lands; and therefore of violent currents and flood waves, seemingly rushing down from, or round the shores of that Wealden island to the south of us, on the shore of which island Odiham once stood. We know this from the great irregularity of the beds: while the absence of that irregularity proves to us that the London clay was deposited in a quiet sea.

But more. A great change in the climate of this country had taken place meanwhile; slowly perhaps: but still it had taken place.

In the lowest clay above the chalk are found at Reading many leaves, and buds, and seeds of trees, showing that there was dry land near; and these trees, as far as the best botanists can guess, were trees like those we have in England now. Not of the same species, of course: but still trees belonging to a temperate climate, which had its regular warm summer and cold winter.

But before the London clay had been all deposited, this temperate climate had changed to a tropical one; and the plants and animals of the upper part of the London clay had begun to resemble rather those of the mouths of the African slave-rivers.

Extraordinary as this is, it is certainly true.

We know that the country near the mouth of the Thames, and probably the land round us here, was low rich soil, some half under water, some overflowed by rivers; some by fresh or brackish pools. We know all this; for we find the shells which belong to a shallow sea, mixed with fresh-water ones. We know, too, that the climate of this rich lowland was a tropical one. We know that the neighbourhood of the Isle of Sheppey, at the mouth of the Thames, was covered with rich tropic vegetation; with screw pines and acacias, canes and gourds, tenanted by opossums, bats, and vultures: that huge snakes twined themselves along the ground, tortoises dived in the pools, and crocodiles basked on the muds, while the neighbouring seas swarmed with sharks as huge and terrible as those of a West Indian shore.

It is all very wonderful, ladies and gentlemen: but be it is: and all we can say is, with the Mussulman--"God is great."

And then--when, none knows but God--there came a time in which some convulsion of nature changed the course of the sea currents, and probably destroyed a vast tract of land between England and France, and probably also, that sunken island of Atlantis of which old Plato dreamed--the vast tract which connected for ages Ireland, Cornwall, Brittany, and Portugal. That convulsion covered up the rich clays with those barren sands and gravels, which now rise in flat and dreary steppes, on the Beacon Hill, Aldershot Moors, Hartford Bridge Flat, Frimley ridges, and Windsor Forest. That rich old world was all swept away, and instead of it desolation and barrenness, piling up slowly on its ruins a desert of sand and shingle, rising inch by inch out of a lifeless sea. There is something very awful to me in the barrenness of those Bagshot sands, after the rich tropic life of the London clay. Not a fossil is to be found in them for miles. Save a few shells, I believe, near Pirbright, there is not a hint that a living being inhabited that doleful sea.

But do not suppose, gentlemen and ladies, that we have yet got our gravel-pit made, or that the way-worn pebbles of which it is composed are near the end of their weary journey. Poor old stones! Driven out of their native chalk, rolled for ages on a sea-beach, they have tried to get a few centuries' sleep in the Eocene sands on the top of the chalk hills behind us, while the London clay was being deposited peacefully in the tropic sea below; and behold, they are swept out, once more, and hurled pell-mell upon the clay, two hundred feet over our heads.

Over our heads, remember. We have come now to a time when Hartford Bridge Flats stretched away to the Beacon Hill, and many a mile to the south-eastward--even down into Kent, and stretched also over Winchfield and Dogmersfield hither.

What broke them up? What furrowed out their steep side-valleys? What formed the magnificent escarpment of the Beacon Hill, or the lesser one of Finchamstead Ridges? What swept away all but a thin cap of them on the upper part of Dogmersfield Park, another under Winchfield House; another at Bearwood, and so forth?

The convulsions of a third world; more fertile in animal life than those which preceded it: but also, more terrible and rapid, if possible, in its changes.

Of this third world, the one which (so to speak) immediately preceded our own, we know little yet. Its changes are so complicated that geologists have as yet hardly arranged them. But what we can see, I will sketch for you shortly.

A great continent to the south--England, probably an island at the beginning of the period, united to the continent by new beds--the Mammoth ranging up to where we now stand.

Then a period of upheaval. The German Ocean becomes dry land. The Thames, a far larger river than now, runs far eastward to join the Seine, and the Rhine, and other rivers, which altogether flow northward, in one enormous stream, toward the open sea between Scotland and Norway.

And with this, a new creation of enormous quadrupeds, as yet unknown. Countless herds of elephants pastured by the side of that mighty river, where now the Norfolk fisherman dredges their teeth and bones far out in open sea. The hippopotamus floundered in the Severn, the rhinoceros ranged over the south-western counties; enormous elk and oxen, of species now extinct, inhabited the vast fir and larch forests which stretched from Norfolk to the farthest part of Wales; hyenas and bears double the size of our modern ones, and here and there the sabre-toothed tiger, now extinct, prowled out of the caverns in the limestone hills, to seek their bulky prey.

We see, too, a period--whether the same as this, or after it, I know not yet--in which the mountains of Wales and Cumberland rose to the limits of eternal frost, and Snowdon was indeed Snowdon, an alp down whose valleys vast glaciers spread far and wide; while the reindeer of Lapland, the marmot of the Alps, and the musk ox of Hudson's Bay, fed upon alpine plants, a few of whose descendants still survive, as tokens of the long past age of ice. And at every successive upheaval of the western mountains the displaced waters of the ocean swept over the lower lands, filling the valley of the Thames and of the Wey with vast beds of drift gravel, containing among its chalk flints, fragments of stone from every rock between here and Wales, teeth of elephants, skulls of ox and musk ox; while icebergs, breaking away from the glaciers of the Welsh Alps, sailed down over the spot where we now are, dropping their imbedded stones and silt, to confuse more utterly than before the records of a world rocking and throbbing above the shocks of the nether fire.

At last the convulsions get weak. The German Ocean becomes sea once more; the north-western Alps sink again to a level far lower even than their present one; only to rise again, but not so high as before; sea-beaches and sea-shells fill many of our lower valleys; whales by hundreds are stranded (as in the Farnham vale) where is now dry land. Gradually the sunken land begins to rise again, and falls perhaps again, and rises again after that, more and more gently each time, till as it were the panting earth, worn out with the fierce passions of her fiery youth, has sobbed herself to sleep once more, and this new world of man is made. And among it, I know not when, or by what diluvial wave out of hundreds which swept the Pleistocene earth, was deposited our little gravel-pit, from which we started on our journey through three worlds.

When?

Enough for us that He knows when, in whose hand are the times and the seasons--God the Father of the spirits of all flesh.

And now, ladies and gentlemen, take from hence a lesson. I have brought you a long and a strange road. Starting from this seemingly uninteresting pit, we have come upon the records of three older worlds, and on hints of worlds far older yet. We have come to them by no theories, no dreams of the fancy, but by plain honest reasoning, from plain honest facts. That wonderful things had happened, we could see: but why they had happened, we saw not. When we began to ask the reason of this thing or of that, remember how we had to stop, and laying our hands upon our mouths, only say with the Mussulman: "God is great." We pick our steps, by lanthorn light indeed, and slowly, but still surely and safely, along a dark and difficult road: but just as we are beginning to pride ourselves on having found our way so cleverly, we come to an edge of darkness; and see before our feet a bottomless abyss, down which our feeble lanthorn will not throw its light a yard.

Such is true science. Is it a study to make men conceited and self- sufficient? Believe it not. If a scientific man, or one who calls himself so, be conceited, the conceit was there before the science; part of his natural defects: and if it stays there long after he has really given himself to the patient study of nature, then is he one of those of whom Solomon has said: "Though you pound a fool in a mortar among wheat with a pestle, yet will not his folly depart from him."

For what more fit to knock the conceit out of a student, than being pounded by these same hard facts--which tell him just enough to let him know--how little he knows? What more fit to make a man patient, humble, reverent, than being stopped short, as every man of science is, after each half-dozen steps, by some tremendous riddle which he cannot explain--which he may have to wait years to get explained-- which as far as he can see will never be explained at all?

The poet says: "An undevout astronomer is mad," and he says truth. It is only those who know a little of nature, who fancy that they know much. I have heard a young man say, after hearing a few popular chemical lectures, and seeing a few bottle and squirt experiments: Oh, water--water is only oxygen and hydrogen!--as if he knew all about it. While the true chemist would smile sadly enough at the youth's hasty conceit, and say in his heart: "Well, he is a lucky fellow. If he knows all about it, it is more than I do. I don't know what oxygen IS, or hydrogen, either. I don't even know whether there are any such things at all. I see certain effects in my experiments which I must attribute to some cause, and I call that cause oxygen, because I must call it something; and other effects which I must attribute to another cause, and I call that hydrogen. But as for oxygen, I don't know whether it really exists. I think it very possible that it is only an effect of something else--another form of a something, which seems to make phosphorus, iodine, bromine, and certain other substances: and as for hydrogen--I know as little about it. I don't know but what all the metals, gold, silver, iron, tin, sodium, potassium, and so forth, are not different forms of hydrogen, or of something else which is the parent of hydrogen. In fact, I know but very little about the matter; except this, that I do know very little; and that the more I experiment, and the more I analyse, the more unexpected puzzles and wonders I find, and the more I expect to find till my dying day. True, I know a vast number of facts and laws, thank God; and some very useful ones among them: but as to the ultimate and first causes of those facts and laws, I know no more than the shepherd-boy outside; and can say no more than he does, when he reads in the Psalms at school: "I, and all around me, are fearfully and wonderfully made; marvellous are Thy works, and that my soul knoweth right well."

And so, my friends, though I have seemed to talk to you of great matters this night; of the making and the destruction of world after world: yet what does all I have said come to? I have not got one step beyond what the old Psalmist learnt amid the earthquakes and volcanoes of the pastures and the forests of Palestine, three thousand years ago. I have not added to his words; I have only given you new facts to prove that he had exhausted the moral lesson of the subject, when he said:

These all wait upon thee, that thou mayest give them their meat in due season.

Thou givest, and they gather: thou openest thy hand, and they are filled with good.