Name applied to a dark-gray, glauconitic, fossiliferous shale that occurs in the subsurface near the top of the nearshore facies of the Dorcheat member (new) of the Schuler formation (new) of the Cotton Valley group (rank raised). Named for occurrence near Wesson, Union Co, AR in the Arkla basin. Type section designated and well cuttings described as interval between 5,710 and 5,735 ft in Standard Oil Co. of Louisiana D. A. Zimmerman No. 1, SE SE sec 29, T18S, R16W, Union Co, AR in the Arkla basin. At type well, lower contact is with shale in lower part of Dorcheat. Upper contact is with white fine-grained sandstone of upper part of Dorcheat. Consists at type of 25 ft of dark-gray glauconitic shale with a small gastropod. Recognized in wells in southern AR and northern LA. To south, expands into off-shore facies. Cross sections. Late Jurassic age.

Source: GNU records (USGS DDS-6; Denver GNULEX).