Iowa Heritage Digital Collections
State Library of Iowa

Browse Items (748 total) for Calvin Geological Photographs

Gorge in Trenton Limestone at Pinney's Spring, Iowa, late 1890s or early 1900s
Gorge in Trenton Limestone at Pinney's Spring, Iowa, late 1890s or early 1900s
Oneota valley from the south and peneplain, Iowa, late 1890s or early 1900s
Cliff above Rawson's Mill.  The thick ledge at the summit is Niagara limestone.  Iowa, late 1890s or early 1900s
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