Pg 119

          Springs issue from all formations, and from the sides of almost every valley, but they are more numerous, and assume proportions which give rise to the name of sink-holes, along the upland borders of the Upper Iowa River, owing . . .

Pg 120

. . . to the peculiar fissured and laminated character and great thickness of the strata of the age of the Trenton limestone which underlies the whole region of the valley of that stream.

          No mineral springs, properly so called, have yet been discovered in Iowa, though the water of several artesian wells is frequently found charged with soluble mineral substances.