TRAVERSE GROUP OF MICHIGAN 519 



The last paper of the morning session was the following : 



TEA VERSE GROUP OF MICHIGAN 

 BY A. W. GRABAU 



[Abstract] 



Two sections, one on Thunder bay and the other on Little Traverse bay, show 

 the strongly calcareous facies of the strata, which is most marked in the western 

 section. In both sections the upper limit of the Traverse group is indicated by the 

 Saint Clair black shale, and the lowest portion of the group is a bed of blue clay 

 80 feet thick. The fauna varies with the rock. The reef character of the lime- 

 stone strata was discussed. 



Questions and remarks were made on Mr Grabau's paper by H. S. 

 Williams and the President. 



At 12.20 p m the Society adjourned for the noon recess. At 2 p m 

 the Society met and resumed the reading of papers. The first paper 

 was 



LOWER CARBONIFEROUS AREA IN INDIANA* 

 BY T. C. HOPKINS 



[Abstract] 



In the southern and west central portions of Indiana the strata of Lower Carbon- 

 iferous age are divided into five well marked lithologic units as follows: 



The Huron limestone and sandstone. 



The Mitchell limestone. 



The Bedford oolitic limestone. 



The Harrodsburg limestones and shales. 



The Knobstone shales and sandstones. 

 The upper division, the Huron, is overlain by the Mansfield sandstone, a 

 heavy bed of sandstone and conglomerate which forms the base of the Coal 

 Measures, while the lower division, the Knobstone, is underlain by the Devonian 

 black shales. 



The lower group consists of a thick series of drab-colored shales, which locally 

 grade into sandstones of sufficient firmness to be quarried in some places for build- 

 ing stone. It is one of the thickest formations in the state, reaching in places 

 more than 500 feet. It forms many quite prominent hills or knobs in the central 

 and southern portions of the area, which suggests the origin of the name.f 



The second division, the Harrodsburg limestone, is so called from the village of 

 that name in Lawrence county, where the rock is well exposed. It consists of 

 crystalline to subcrystalline fossiliferous limestones, in places very crinoidal, with 

 more or less intercalary shale. It forms a transition bed from the underlying 



*By permission of the State Geologist of Indiana. Full paper published in the 26th Ann. Rept. 

 State Geologist of Indiana along with a new geological map of the State. 



fFor detailed description of this group see paper by J. F. Newsom in 26th Ann. Rept. State Geol- 

 ogist of Indiana, 1901. 



