Written in the Hills
Geology of the Ozarks, part 3
Bruce Stinchcomb

The Cambrian rocks and fossils of the Ozarks. A major portion of the Ozarks (especially in Missouri),
have Cambrian age rocks cropping out at the surface. These are usually beds of dolomite, shale and
sandstone, with the dolomite beds often containing large amounts of chert and flint which (perhaps)
makes the Ozarks the chert (and flint) capital of the world. Locally the rocks can contain marine fossils,
fossils over half a billion years old from organisms which lived in the shallow seas and from which sediments
the rocks were formed. Mentioned are also the Ozarks extensive lead (galena) deposits which occur in
Cambrian age rocks (Bonneterre Formation). Also mentioned are the peculiar quartz crystals and barite
occurrences (no longer mined). Fossil monoplacophorans are mentioned which were probably the
ancestors of the cephalopods (like the squid and octopus). Some of the large springs of the Ozarks are
shown as well as the tall dolomite bluffs along the Current and Jacks Fork rivers within the Ozark National
Scenic Waterways. Caves, especially those of the Eminence Formation are mentioned which includes
Meramec Caverns and Onondaga Cave both near former route 66.

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Ozarks Paleontology