Page:History of Iowa From the Earliest Times to the Beginning of the Twentieth Century Volume 1.djvu/37



of humanity seem to strive,—'to eat and to escape being eaten.' Not only may we restore the forests in the shadow of which prehistoric man lived, we may know the size and habits of the animals that roamed through the forest; those that man chased and those from which he in turn fled; we may even go farther and determine the climatic conditions under which all this assemblage of animal and plant life existed.”

Geology unfolds to us a wonderful history of the most remote periods of time, which reduced to language reads like a fairy tale. It tells us nearly all we know of the countless years that passed away while the continent, of which Iowa is a part, was in the process of formation. Professor Calvin continues:

“These geologic records, untampered with, and unimpeachable, declare that for uncounted years Iowa, together with the great valley of the Mississippi, lay beneath the level of the sea. So far as it was inhabited at all, marine forms of animals and plants were its only occupants.”

During the ages of submergence, the sedimentary strata of Iowa, as well as of all the adjacent States, was being formed on the sea bottom. This formation contains a record of a period of duration altogether incomprehensible. Centuries pass while the light colored limestones so well represented at Anamosa are slowly forming by an imperceptible sedimentary accumulation. Other ages come and go while the limestones represented in Johnson County are forming. About this time a small portion of northeastern Iowa rises above the sea, while all the vast region south and west is still buried deep beneath the all pervading water. Odd shaped fishes and a species of ferns mark the highest point reached in the evolution of animal and plant life at this time.

Ages again go by while the sediment of the sea is forming beds of rock which appear in Marshall, Des Moines and Lee counties. Then slowly come the Coal measures and rocks above them. Ferns and air-breathing creatures have made their appearance. The sea gradually recedes to the southward and the surface of our whole State is visible. Later forests and other forms of vegetation cover