Brereton cyclical formation. [A name applied to lower part of McLeansboro formation (Pennsylvanian) and uppermost part of Carbondale formation (Pennsylvanian) of central-western Illinois, based upon the rhythmic-cycle theory of sedimentation. Includes coal No. 6. Origin of name not stated.]

Source: US geologic names lexicon (USGS Bull. 896, p. 259).

Pg. 145 (table 1). Brereton cyclothem. In list of Upper Pennsylvanian cyclothems, occurs below Jamestown cyclothem (new).

Source: US geologic names lexicon (USGS Bull. 1200, p. 468).

Pg. 50 (fig. 22), 60-61, 103-113, pl. 5. Brereton cyclothem in Carbondale group. Described in Beardstown, Glasford, Havana, and Vermont quadrangles, west-central Illinois, where it includes (ascending) Cuba sandstone. Big Creek shale, Herrta (No. 6) coal, Brereton limestone, and Sheffield shale. Underlies Pokeberry cyclothem believed to be equivalent to Jamestown cyclothem. Age is Pennsylvanian. Origin of name and type locality given.
Type section: along Middle Branch of Copperas Creek, 2 mi northeast of Brereton, in NE/4 SE/4 NE/4 sec. 1, T. 7 N., R. 4 E., Glasford 15-min quadrangle, Fulton Co., central western IL.

Source: US geologic names lexicon (USGS Bull. 1200, p. 468).

Pg. 52 (table 2), pl. 1. Brereton cyclothem. Above St. David cyclothem and below Jamestown cyclothem. Age is Pennsylvanian. Report presents new rock-stratigraphic classification of Pennsylvanian strata in Illinois. Cyclical classification retained but is entirely independent of rock-stratigraphic classification; includes rocks also assigned to Carbondale formation of Kewanee group (new).

Source: Publication; US geologic names lexicon (USGS Bull. 1200, p. 468).