Erosion occurs in the Interior Highlands. Present only in the subsurface in southern Arkansas. Erosion occurs in the Interior Highlands. Intrusion of small localized bodies of magma in southern Arkansas, which crystallized to form igneous rocks. Triassic 208 to 245 Ma Accumulation of predominantly red clay and silt, sand and gravel, and minor beds of anhydrite in a non-marine environment.
Age is indefinite.
Erosion occurs in the Interior Highlands. Last interval of uplift of the Interior Highlands and end of milky quartz-vein formation. Deposition of clastic sediments occurs. Rapid infilling of clastic sediments and development of growth faults along northern basin margin. Concurrent formation of quartz veins.