272 GEOLOGY OF ILLINOIS. 



cloned. The beds exposed in the vicinity of Gall's mines give the fol- 

 lowing section : 



No. 1. Calcareous shales 6 to 8 feet. 



No. 2. Compact argillaceous, dark-blue limestone 3 to 4 



No. 3. Bituminous shale 1 to 3 



No. 4. Coal (Belleville seam) 3 to 4 



No. 5. Calcareous shales and nodular limestone 3 to 4 



No. 6. Shale and shaly sandstone 15 



The limestone and shales forming Nos. 1 and 2 of the above sec- 

 tion closely resemble the beds usually overlaying the Belleville coal, in 

 St. Clair county, and contain the same group of fossils, among which 

 are Spirifer cameratus, S. Uneatus, Athyris subtilita, A. Boyissiij Cho- 

 netes mesoloba, C. Smithii, Productus punctatus, P. costatus, P. Pratteni- 

 amtSj P. longispinus and Trachydoma nodosa. Hence we have referred 

 this coal to the horizon of the Belleville seam, although the seam is not 

 so thick here as it is in St. Clair county, and the coal it affords is infe- 

 rior in quality. We saw no indication of the development of the 

 Heuckler scam, in this vicinity, though it is not improbable that it may 

 be found in some portion of this isolated basin. On the creek running- 

 through Mr. Gall's land w r e found continuous exposures from his coal, 

 down to the Lower Carboniferous limestones, without any indications 

 of the presence of any underlaying seam. A little to the eastward of 

 Gall's old shaft the St. Louis limestone may be seen in heavy beds, 

 dipping west 20 deg. south, at an angle of about 30 deg., overlaid by 

 the Chester beds, dipping in the same direction and at a slightly de- 

 creased angle, while the beds of the Coal Measures lie nearly horizonal, 

 and rest unconforrnably upon the subordinate limestones. On the west- 

 ern side of this synclinal the dip of the limestones is much less, varying 

 from 6 to 10 deg. to the eastward. 



Over some portion of this synclinal valley the coal has been swept 

 away by denuding forces, and heavy beds of drift clay now occupy the 

 place of the coal deposits ; and it is not probable that any considerable 

 area is now underlaid by coal of sufficient thickness to be profitably 

 mined, in competition with the well developed coals of St. Clair county. 

 However, the completion of the narrow-gauge railroad from St. Louis, 

 south through this neighborhood, may afford a better market for coal 

 than they have heretofore had, and should stimulate research to develop 

 whatever fuel resources exist in the county. 



Chester Group. This upper group of the Lower Carboniferous system, 

 as developed in this county, consists of a heavy bed of sandstone form- 

 ing its lower division, above which there are two or three beds of lime- 

 stone, alternating with sandstones and sandy and argillaceous shales ; 

 the whole series thinning out to the northward, and scarcely attaining 

 to one-half the thickness in this county that they have iu Randolph. 



