STATE GEOLOGIST. IT 



ter of a black bituminous shale. In Mr. Canwright's well, near 

 Ooldwater, the upper part is also bituminous, but soon passes 

 into a plastic dark blue clay, which he has worked very exten- 

 sively in the vicinity, in the manufacture of bricks. For this 

 use, the kidney iron clays are generally well adapted. 



No fossils have been detected in this group in the southern 

 part of the State, except a Tellina, a Solen undistinguishable 

 from one in the Marshall Group, a Ghonetes and a Grammysia. 



The bituminous character of most of the shales of this group, 

 * 

 and especially of that portion known as the "Black Bituminous- 

 Shales," has given rise to numerous misapprehensions in regard 

 to their geological relations, and has been the occasion of the 

 practice of a great amount of geological quackery The pop- 

 ular opinion is, that coal must exist somewhere in the vicinity 

 of the black shales. The opportunity has been very many 

 time3 presented for discouraging explorations contemplated or 

 undertaken, under the influence of this illusion. Large tracts 

 of land have been secretly taken up, with the view of securing 

 eligibly situated coal mines. The reports so rife among the 

 Indians and their missionaries, of the occurrence of coal in 

 the neighborhood of Grand Traverse Bay, are undoubtedly 

 traceable to the same illusory shale. There is not the remotest 

 probability of the occurrence of coal within a hundred miles of 

 Grand Traverse Bay. This statement is made in full recollec- 

 tion of the allegation of a learned judge, that he had seen 

 anthracite coal that was said to have been collected in that region. 

 One of the localities, of Indian notoriety, is at the southern 

 extremity of Mucqua Lake, south of Little Traverse Bay. The 

 Indians report that they have often resorted there for fuel, and 

 that they have burned the coal in their camp fires — a statement 

 perfectly credible if we substitute shale for coal. 



Similar misguided expenditures have been made in the same 

 rocks in Canada, New York, Ohio and other States. 



The geological positon and equivalents of the Huron Group 

 of rocks, cannot yet be regarded as satisfactorily settled, and 

 for this reason they have received a provisional, local name. 



