269 



The Hueon Group in Western Monroe and Eastern 

 Greene Counties, Indiana. 



By F. C. Greene. 



The opening of the right-of-way of the Indianapolis Southern Railway 

 between Indianapolis. Indiana, and Effingham, Illinois, presented an un- 

 usual opportunity for the study of the so-called Huron group, west of Bloom- 

 ington, Indiana, in western Monroe and eastern Greene counties. The 

 Huron group is the youngest formation of the Mississippian of Indiana. 

 The name Huron was first apji^lied by Dr. Ashley in his paper on the 

 Lower Carboniferous Area of Southern Indiana.^ 



The type locality is at Huron, Lawrence County, a station on the B. & 

 O. S.-W. Railway. According to his definition, the boundaries of the Huron 

 group are fixed at the base of the lowest sandstone in the group and the 

 unconformity at the top which marks the division between the Mississip- 

 pian and Pennsylvanian. The discussion of his reasons for so drawing 

 the limits at these points may be found in his report and will not be re- 

 l)eated here. However, as the name Huron is preoccupied-, it must be 

 replaced by another, and it is here proposed to substitute the name Chester, 

 as the group can be correlated with the upper Mississippian of Illinois 

 or Kentucky. 



Blatchley gives a concise summary of the formation.' He says. "In 

 Orange County, where the Huron group is perhaps the most typically ex- 

 posed, it is represented by a lower limestone, a lower sandstone, a middle 

 limestone, an upper sandstone and an upper limestone 



The lower Huron limestone is a compact, smooth-grained, ash-gray to 

 blue limestone, which varies from five to eight feet in thickness. In struc- 

 ture it is a close-grained, fine-textured, non-crystalline stone, breaking with 

 a sub-conchoidal fracture 



' Ashley, G. H., Dcpt. of Geol. and Nat. Res. of Ind.. 1902. 



2 In the Rept. of Progress in 1869, Geol. Survey of Ohio, Part I, p. 18, Dr. S. 

 W. Newberry proposed the name Huron for a shale formation of the Devonian of 

 Ohio. 



^Blatchley, W. S., Thirtieth Ann. Rept. Ind. Dept. Geol. and Nat. Res., pp. 144- 

 145. 



