Pg. 37, 49 (table 1), pl. 1. Lake Creek coal member of Modesto formation of Modesto formation (new) of McLeansboro group. Name applied to coal encountered at depth of 86.5 feet in drillhole. Occurs above Pond Creek coal member (new) and below West Franklin limestone member. Coal has been referred to informally as 3rd Cutler Rider coal. Name credited to Cady (unpub. ms.). Piasa limestone and DeGraff, Pond Creek, and Lake Creek coals may be included in complex West Franklin limestone in eastern part of area. Age is Pennsylvanian. Presentation of new rock-stratigraphic classification of Pennsylvanian in Illinois. Cyclical classification is retained but is entirely independent of rock-stratigraphic classification.
Type locality (subsurface): depth 86.5 feet, Consolidated Coal Company No. 91 drillhole, in SW/4 NE/4 NE/4 sec. 21, T. 8 S., R. 3 E., Williamson Co., southeastern IL. Named from Lake Creek Twp. in which drillhole is located.

Source: US geologic names lexicon (USGS Bull. 1200, p. 2081).