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.