Geologic units in Oregon county, Missouri

Smithville Dolomite, Powell Dolomite, Cotter Dolomite, Jefferson City Dolomite (Early Ordovician-Ibexian Series) at surface, covers 60 % of this area

Fine crystalline, silty, cherty dolomite, and oolitic chert with local sandstone beds.

Roubidoux Formation (Early Ordovician-Ibexian Series) at surface, covers 35 % of this area

Sandstone, chert and interbedded dolomite

Gasconade Dolomite (Early Ordovician-Ibexian Series) at surface, covers 5 % of this area

Coarse - crystalline cherty dolomite with a basal Gunter Sandstone Member.

Cotter and Jefferson City Dolomites (Early Ordovician) at surface, covers 0.1 % of this area

Cotter and Jefferson City Dolomites

Pennsylvanian Undifferentiated (Pennsylvanian) at surface, covers < 0.1 % of this area

Pennsylvanian Undifferentiated