Now, in this section of the rocks which we have as they are stratified, formed in layers one above the other, we come to the idea of time. I was going along this morning, with a basket and one of these stones in my hand, and a man’s attention was attracted, and he asked how long since those animals were alive. I said a million of years. He looked rather astonished, and expressed himself that I could not know. The idea of such great amounts of time strikes any one like the vast areas of space. At the first step in geology we have got to expand our notions of time. The six thousand years will not do. Some people think there is something in the Bible about six thousand years. There is no such thing. It is a chronology that has grown up like Milton’s Paradise Lost. Many people think that Milton’s Paradise Lost is a part of the Bible. In Genesis we are told of days, which everybody understands to mean periods of time, and of time since the beginning, when the earth was without form and void. We have nothing definite said in the Bible, or any other book, except the approximate indications which are found in the great stone book of Nature. Let us look at the idea of time, and see how we get at it. If we should come again to the mud puddle dried up, we should get an approximate idea of how long it took to form the deposit. Suppose we do not know the history, we know about the number of storms that are usual, and the amount of rainfall, and we have some guide in that succession of layers that are there. In the ancient rocks we have exactly the same guide. Somebody says in answer to all this, that in some places deposits take place very rapidly, and we can not judge. For instance, a flood in the Mississippi bears down a vast amount of matter. There is a delta of the Mississippi that has been built out during the memory of man. Whenever we find coarse material in a delta we say it was rapidly formed; if it is fine material, we say it was formed slowly. To-day the Mississippi is bearing down a vast mass of material, and the coarser materials drop by the mouth, but the finer are carried out over the sea, perhaps along the shore. This fine silt settles down amid the corals, the sea-weed and the ships. If the ocean could be drained, we would find on the decks of the ships that have been sunk a hundred years, as the divers tell us, this deposition on the bottom of the sea. No one can doubt about these deposits which have so many shells, that the deposit was made very slowly, because it would have been impossible for the shells to have lived if the material had been thrown down rapidly.