422 ILLINOIS STATE ACADEMY OP SCIENCE 



2, Matherville section: 



During the field work last fall in preparation for a 

 report on the coal resources of District III, Fusulinas 

 were obtained from the cap rock of what was reported 

 as No, 1 coal in the Pottsville series. 



The section at Matherville where the Fusnlina lime- 

 stone is well exposed includes about forty feet of sand- 

 stone and sandy shale, with purer shale on top. Below is 

 a dark, massive, argillaceous bed several feet thick, 

 known to the miners as the ''blue rock". Below this is 

 the tAvo foot, dark, argillaceous limestone which carries 

 Fusulinas and which caps the coal of the region. Beneath 

 the coal, which is here only 30 inches thick, is a sandy 

 shale which grades to sandstone in less than a yard. Lo- 

 cally there are variations from this section. In southern 

 Mercer County a second limestone and lower coal appear 

 along Pope Creek. In eastern Eock Island County the 

 upper sandy beds include layers and lenses of flint. In 

 places the limestone cap thins out as though removed by 

 erosion prior to the deposition of the overlying beds. A 

 still more common variation is the presence of a few 

 inches to several feet of shale between the coal and the 

 limestone cap. 



Disregarding these variations this same section ap- 

 pears in much of the adjoining area. Thus at the Alden 

 Mine at Matherville, at the mines at Cable and Sherrard, 

 at outcrops on Camp Creek in northern Mercer County, 

 and along the Mississippi bluffs west of Andalusia, are 

 found the blue rock, the Fusulina cap rock, and the coal. 



Eastward the Fusulina limestone is found at Coal Val- 

 ley and both north and west of Geneseo. Following the 

 margin of the Pennsylvanian area southward the Fusul- 

 ina limestone and associated beds are found in Warren, 

 Knox, Fulton, and McDonough counties. 



The Fusulinas appear to be restricted to the limestone 

 overlying the coal, but are by no means uniformly dis- 

 tributed through even this thin stratum. They are most 

 abundant in the lower part of the bed, although rarely 

 found in the basal six inches. 



