AGS / Education / Geology Resources / Physiographic Regions / West Gulf Coastal Plain / Geology
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 clays with lignite beds.
Tertiary outcrop near Little Rock
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
Gypsum beds in the DeQueen Limestone