OF IOWA | 3 |
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:
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