Page:Popular Science Monthly Volume 53.djvu/41

Rh duration of geological time. It is such magnificent land forms as these plateaus and great valleys, found submerged beneath the sea, which have furnished us with the means for measuring the terrestrial



movements in the opposite direction which have reduced the West Indian region to a group of islands.

As to the causes of these terrestrial movements, at present little can be said. Changes of level of land and sea, similar to those found