Geology Web Map

The geology of the map below represents geological mapping projects in the Ouachitas and Arkansas River Valley under the COGEO mapping program and in the West Gulf Coastal Plain under the STATEMAP program. You can zoom to a chosen county or quadrangle using the drop-down menus located above the map, and you can adjust the opacity of the surface geology layer using the opacity slider opacity slider icon located at the top left corner of the map. For best printing results use either the Mozilla Firefox or Google Chrome web browsers.

ZOOM TO:   County     7.5' Quadrangle
Coordinates format:

Geology Web Map Legend

Inclined bedding - Showing approximate strike and dip Overturned bedding - Showing approximate strike and dip
Contact - Existence certain, location approximate Igneous Dike - Existence certain, location approximate
Normal Fault - Existence certain, location approximate Normal Fault - Inferred or concealed
Tear Fault - Existence certain, location approximate Tear Fault - Inferred or concealed
Thrust Fault - Existence certain, location approximate Thrust Fault - Inferred or concealed
Overturned Thrust Fault - Existence certain, location approximate
Alluvium - Quaternary Sand & Gravel - Quaternary
Stream Overbank - Quaternary Terrace - Quaternary
River Terrace - Quaternary Sand & Gravel - Tertiary
Gravel - Tertiary Claiborne Group - Tertiary
Wilcox Group - Tertiary Midway Group - Tertiary
Arkadelphia Marl - Cretaceous Nacatoch Sand - Cretaceous
Saratoga Chalk - Cretaceous Marlbrook Marl - Cretaceous
Annona Chalk - Cretaceous Ozan Formation - Cretaceous
Brownstone Marl - Cretaceous Tokio Formation - Cretaceous
Woodbine Formation - Cretaceous Kiamichi/Goodland Formation - Cretaceous
Trinity Group - Cretaceous De Queen Limestone - Cretaceous
Dierks Limestone - Cretaceous Igneous Rocks - Cretaceous
Boggy - Pennsylvanian, Desmoinesian Series Savanna - Pennsylvanian, Desmoinesian Series
McAlester - Pennsylvanian, Desmoinesian Series Hartshorne Sandstone - Pennsylvanian, Desmoinesian Series
Upper Atoka - Pennsylvanian, Atokan Series Middle Atoka - Pennsylvanian, Atokan Series
Lower Atoka - Pennsylvanian, Atokan Series Johns Valley Shale - Pennsylvanian, Morrowan Series
Jackfork Sandstone - Pennsylvanian, Morrowan Series Stanley Shale - Mississippian
Arkansas Novaculite - Devonian and Early Mississippian Missouri Mountain Shale - Silurian
Blaylock Sandstone - Silurian Missouri Mountain Shale / Polk Creek Shale - Silurian and Late Ordovician
Polk Creek Shale - Late Ordovician Bigfork Chert - Middle and Late Ordovician
Womble Shale - Middle Ordovician Blakely Sandstone - Middle Ordovician
Mazarn Shale - Early Ordovician Crystal Mountain Sandstone - Early Ordovician
Collier Shale - Late Cambrian and Early Ordovician Strip Mine