The _ages_ into which the _times_ were divided have their names either from what was produced in them, or from the part of the world where their rocks chiefly appear on the present surface. Thus the Carboniferous age is the carbon or coal age, because then most of our coal-beds were formed. The Silurian age, on the other hand, takes its name from a part of Wales, where its rocks are most conspicuous, and in this part of Wales a people called Silures used to live. A study of the “Table of Earth-building,” which is the frontispiece of this book, will show clearly these times and ages. It is concluded that the first land which appeared was a range of rocks, which is best known in the valley of the St. Lawrence River, and represents the oldest land on the globe. We need not fancy that the new continent occupied a large part of the globe; it was comparatively very small. Neither can we look for it to-day, and find it as when it rose over the hot ocean. The first land of the world lifted above the waters and sank again, and so rose and sank more than once or twice in great lapses of time. This rising and sinking was caused by the action of heat and steam in the interior of the earth, which elevated and rent the crust. From Labrador to Lake Superior the old Laurentian rocks crop out. If you go to the Adirondack Mountains, you stand on the first continent, though it is now covered with a soil which did not exist in that early time of its uplifting. There are spots of this old continent in Nova Scotia, New Brunswick, Sweden, Norway, Bavaria, and the Hebrides. These are then, the oldest parts of the world, and you could take your atlas, and by sketching a continent, long, narrow, and crooked, that would cover these places with a few outlying islands to help it out, you would have a fair idea of the first continent. Probably nothing grew on it, but in the sea there were some plants and animals. The beds of Laurentian rocks in North America are sometimes thirty thousand feet thick. These early rocks, more than any others, show the action of great heat. The action of heat has changed the rocks from their first condition. Time and heat will turn sand, lime, and clay into crystal and marble. For a long time the Laurentian age was supposed to have been wholly destitute of any life, and was called the azoic, or life-lacking time. But Sir William Dawson, after long explorations among the Laurentian rocks, found in them the fossil remains of a once living creature. He named this creature the Dawn Animal, or Eozoön. The name suggests that this is the most ancient animal yet discovered, and represents the dawn of life on our planet.