Next after the highlands north of the St. Lawrence up came the tops of the mountains you see running along the eastern coast, what we now call the Appalachians. Then the Rocky Mountains began to raise their heads and looked eastward toward their brother mountains across a great mediterranean sea, the bottom of which is now the Mississippi Valley. Mediterranean means "middle of the land." [Illustration: HOW YOUR GEOGRAPHY ROSE OUT OF THE SEA] ADMITTING NEW STATES TO THE MAP Wisconsin, into which I moved from the Laurentian Highlands in later years, was on the lower end of a long, thin tongue of rock reaching out from these highlands to the southwest. While Wisconsin went on growing, the Alleghanies came up and brought some Middle Atlantic geography with them. Up with all these early settler mountains came, in the course of time, the beginnings of neighbor States. All these big, barren rocks (as they were then), rising and ever rising, age after age, spread more surface to the sun. And the sun, and the wind, and the frost, followed by the lowest forms of plant life--the Adams of the vegetable world--gradually worked the surface of the rock into soil; and so, as we may say, got ready for the spring plowing. [Illustration: LANDS THE SEA HAS SWALLOWED Parts of the continents as they used to be but which are now beneath the waters are here shown. Compare this with the globe map in your geography. It is estimated that there are 10,000,000 square miles of this land. You'll hear more about this swallowing habit of the sea in Chapter X; but, as you will learn, there's nothing to be frightened about. ] By this constant rising and building on of the soil the foundations of our States grew out toward one another in order, according to the constitution of things, "to form a more perfect union." The United States, at a time which, we may say, corresponds to "The Expansion Period" in your school history, grew southward from Wisconsin and westward from the Appalachians until they made continuous land; and there was your Ohio and Indiana and the rest of the North Central group. Below, toward the south, were more big stone islands here and there, the first sketches or blockings out of the Southern States. Florida seems to have been added later, as a final touch; an afterthought, as one of my Wisconsin neighbors puts it. And it was much enlarged by those remarkable little world builders, the corals. Mexico and Central America, of course, are a part of the Rocky Mountain system. [Illustration: _From Gilbert and Brigham's "An Introduction to Physical Geography." By permission of D. Appleton and Company_ BUT WON'T WE GO UNDER AGAIN?