Pg. 1586 (fig. 1), 1589. Abingdon cyclothem. [Name proposed by Weller and Wanless.] Commonly embryonic and thin; characterized only by a dark streak or coal horizon separating underclay and gray shale; in most areas, identified and correlated solely on basis of its stratigraphic position. In area of Knox and Fulton Counties, Illinois, includes basal sandstone, underclay, and a few inches of coal, and gray shale bearing a thin unpersistent layer of brownish- to purplish-gray fine-grained limestone. Neither a basal sandstone nor a marine limestone is characteristically present, and most distinctive member of cyclothem in Iowa is thin red platy almost fissile shale directly above coal horizon. In western Illinois and Iowa, persistently present between Greenbush cyclothem below and Liverpool cyclothem above. Formerly tentatively termed Lower Liverpool.
Well exposed in tributaries of Brush Creek, especially 4 mi east of Abingdon, near the center of sec. 6, T. 9 N., R. 2 E., Knox Co., western IL.

Source: US geologic names lexicon (USGS Bull. 1200, p. 9-10).

Pg. 50 (fig. 22), 83-85, geol. sections 6, 23, 25, 28-32, 34, 36, 37, 40, 42. Abingdon cyclothem. Includes Isabel sandstone. Also includes a channel sandstone, called Browning by Searight (1929). It is possible Browning may be channel facies of Isabel sandstone. However, in this report Browning is included in Liverpool cyclothem. Cyclothem also present in western Indiana and western Kentucky, where it probably includes lowest beds of Carbondale formation as used in Kentucky.

Source: US geologic names lexicon (USGS Bull. 1200, p. 9-10).

Pg. 52 (table 1), pl. 1. Abingdon cyclothem. Recognized in western Illinois. Occurs above Greenbush cyclothem and below Tonica (new) or Liverpool cyclothem (older terminology). Age is Middle Pennsylvanian (Desmoinesian). Report presents new rock-stratigraphic classification of Pennsylvanian strata in Illinois. Cyclical classification is retained but is entirely independent of rock-stratigraphic classification; includes rocks also assigned to Spoon formation of Kewanee group (both new).

Source: Publication; US geologic names lexicon (USGS Bull. 1200, p. 9-10).