Geologic units in Randolph county, Arkansas

Geologic units in Randolph county, Arkansas

Additional scientific data in this geographic area

Cotter and Jefferson City Dolomites (Early Ordovician) at surface, covers 61 % of this area

Cotter and Jefferson City Dolomites

Alluvium - Alluvial deposits of local streams or of overbank flow of major streams (Holocene) at surface, covers 11 % of this area

Alluvial deposits of local streams or of overbank flow of major streams - In some areas includes deposits in abandoned meanders of major streams

Dune sand (Late Pleistocene) at surface, covers 9 % of this area

Deposited mostly on terrace deposits of the second level. Younger than some terrace deposits, older than others

Sand and clay (Cretaceous) at surface, covers 6 % of this area

Sand and clay

Terrace deposits (Late Pleistocene) at surface, covers 5 % of this area

Alluvial deposits on one or more terrace levels

Alluvium and terrace deposits (Holocene to Pleistocene) at surface, covers 3 % of this area

Alluvial deposits of present streams and on one or more terrace levels

Powell Dolomite (Early Ordovician) at surface, covers 2 % of this area

Powell Dolomite

Alluvium - Alluvial deposits in major stream channels or in mappable meanders of major streams (Holocene) at surface, covers 2 % of this area

Alluvial deposits in major stream channels or in mappable meanders of major streams - Includes alluvial deposits in natural levees in some areas.

Gravel (Tertiary) at surface, covers 0.2 % of this area

Gravel on isolated hills within 40 miles (64km) of the Mississippi Embayment. Many small deposits to the west not shown

Smithville Dolomite, Powell Dolomite, Cotter Dolomite, Jefferson City Dolomite (Early Ordovician-Ibexian Series) at surface, covers < 0.1 % of this area

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