Here is a specimen that I got right here where they are ballasting the road. Here you could see a mass of sand and gravel. It goes on wherever there is sand and gravel and there is lime and water; it is compounded together. We have there fossils. Here, for instance, you have various forms of plants and corals, and so on, and you have here in the rocks right about you shells, coral, seaweed, preserved in the same way. Thus you get your petrefactions. Thus you get the layers that you call strata. All these layers of rock are simply sediment that was once carried down and spread out in a body of water. Is not that simple enough? Here is that slab, all covered over with seaweed and shells, that was one time a bottom of the ocean; there was a volume of clay, and you see resting in there rolls of seaweed. Trailing over this all along these shores on the spot where we now stand, there were seaweed, and coral, and all the animal life. Here is a head of a large animal, a cephalopod, and here is a tail, and the rest of the body is probably under the railroad track. Here is a curved shell. This rock abounds in the ocean. They were the pirates of the ocean. They were the ancient devilfish. They had enormous arms. They were very fine in their time, but, as some one says about the Pilgrim Fathers, we should be thankful that they did not come down to us. We have another class of rocks in our boulders and hard heads. Here are some without any section. Here is a mass of modern lava. Here you see this huge mass. All these landscapes show the different kinds of rocks in their relations. This irregular mass is the unstratified rocks. They have been melted and cooled from a state of melting. We know them to be crystals. They consist of quartz, feldspar, and mica, which are the alphabet of mineralogy. We have the crystals, which we know only exist when there has been a state of melting. These unstratified rocks are the material of all our quarries and great rocks. There are two great classes: the stratified, in layers, which came from sediment deposited in the ancient seas, and the unstratified, which were once melted masses thrown out of the interior of the earth. The granite, the unstratified rocks, form the backbone of the continent; they are the underlying rocks. They occur as veins, coming up through the stratified rocks, and overflowing the surface.