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AGS / Education / Geology Resources / Physiographic Regions / West Gulf Coastal Plain / Geology

Geology of the Tertiary Area

This part of the state contains mostly early Tertiary aged rocks, mostly sands, silts and clays, deposited in streams, swamps and shallow marine water.  Lignite beds occur throughout the sequence.  Quaternary alluvium and terrace deposits are present from rivers in the area.  Underneath the Tertiary deposits are the sands, gravels, limestones, chalks and marls seen in the Cretaceous area.

Wilcox sand and  clay with lignite beds
Wilcox sand and clays with lignite beds.

tertiary outcrop near Little Rock
Tertiary outcrop near Little Rock

Geology of the Cretaceous Area

The geology of the Cretaceous area within the West Gulf Coastal Plain is characterized by gently southward-dipping sedimentary rocks deposited mostly in shallow marine water of the Gulf of Mexico that once extended into Arkansas. Alluvium deposits from older and present day streams are common

The Annona Formation at Whitecliffs near Millwood Lake

                      The Annona Formation at Whitecliffs near Millwood Lake

Gypsum beds in the DeQueen Limestone

Gypsum beds in the DeQueen Limestone

Tokio Gravel

Tokio Gravel                                     

See Cretaceous on map

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Arkansas Geological Survey
Vardelle Parham Geology Center
3815 West Roosevelt Road
Little Rock, AR 72204
Phone: 501-296-1877 | Fax: 501-663-7360
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