But, first, perhaps, I had better tell,--just in outline,--something of the earlier history of the world, before any of our Isle of Wight rocks were made. For, if I do not, quite a wrong idea may be formed of the world's history. The time of the Wealden river has seemed to us very ancient. We cannot say how many hundreds of thousands, or rather millions of years have passed since that ancient Wealden age. And you may have thought that we had got back then very near the world's birthday, and were looking at some of the oldest rocks on the globe. But no. We are not near the beginning yet. Compared with the vast ages that went before, our Wealden period is almost modern. We cannot tell with any certainty the comparative time; but we may compare the thickness of strata formed to give us some sort of idea. Now to the first strata in which fossil remains of living things are found we have in all a thickness of strata some 12 times that of all the rocks we have been studying from Wealden to Oligocene, together with the later rocks, Miocene and Pliocene, not found in the Isle of Wight. And before that there is, perhaps, an equal thickness of sedimentary deposits; though the fossils they, no doubt, once contained have been destroyed by changes the rocks have undergone. Now let me try to give you some idea of the world's history up to the point where we began in the Isle of Wight. If we could see back through the ages to the furthest past of geological history, we should see our world,--before any of the stratified rocks were laid down in the seas,--before the seas themselves were made,--a hot globe, molten at least at the surface. How do we know this? Because under the rocks of all the world's surface we find there is granite or some similar rock,--a rock which shows by its composition that it has crystallised from a molten condition. Moreover we have seen that the interior of the earth is intensely hot. And yet all along the earth must be radiating off heat into the cold depths of space, and cooling like any other hot body surrounded by space cooler than itself. And this has gone on for untold ages. Far enough back we must come to a time when the earth was red hot,--white hot. In imagination we see it cooling,--the molten mass solidifies into Igneous rock,--the clouds of steam in which the globe is wrapped condense in oceans upon the surface. The bands of crystalline rock that rise above the primeval seas are gradually worn down by rain and rivers and waves, and the first sedimentary deposits laid down in the waters. And in the waters and on the land life appeared for the first time,--we know not how.