32 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 304 



Farmdalian Substage Thickness 



Farmdale silt (feet) 



2. Silt, clayey, pink to red and red-brown, calcareous, 



massive to indistinctly bedded but locally thin-bedded 

 and blocky, no fossils observed; locally contains small 

 lenses of fine sand, tan, calcareous; upper contact 

 irregular but lower contact conformable on unit below. 

 From the upper part of this unit in a former working 

 face, wood yielded a C 14 date of 24,000 ±700 (W-79). 10.0 to 20.0 

 1. Silt with some clay and fine sand and locally sandy 



streaks near the top, gray-blue to dark gray or black 



with some tan zones, massive, compact, calcareous; 



contains fauna of aquatic mollusks (locality 8); humus 



staining distributed throughout, numerous twigs and 



wood fragments in upper one-third yielded a C^ 4 date 



of 26,800 ±700 (W-871); rests on St. Peter Sandstone. 25.0 



Total Pleistocene measured 94.0 



Illinois State Geological Survey Circular 304 

 32 p., 3 figs., 4 plates, 11 geol. sections, 1960 



