Where shall we go to find these volcanoes? Are there any upon the Atlantic coast or neighboring highlands? Though you may travel over all that portion of our country, you will find none, although you will discover in places, as for instance in the palisades of the Hudson, lavas which came from very ancient volcanoes, worn down so long ago that their very sites are lost to view.

If we search the Mississippi basin we find there even fewer traces of volcanic action than upon the eastern highlands. The greater portion of the vast area embraced by the Mississippi River and its tributaries has had a very uneventful history, although at times earthquakes may have occurred and the sky may have been darkened by ashes from eruptions in distant parts of the earth.

FIG. 25.—FISSURE IN THE LAVA, SHADOW MOUNTAIN

The groovings in the lava show that it was squeezed out in a half-solid condition

It is in the country west of the Rockies, the region last to be explored and settled, that the objects of our search come to light. Here are volcanoes and lava fields so extensive as almost to bury from sight the older surface of the earth. Some of them appear as if but yesterday they had been glowing with heat.

In the Cordilleran region Nature has carried on her work with a master hand. She has lifted the earth's crust to form a great plateau. Portions of the plateau she has broken, projecting the fragments upward to form