72 REPORT OP THE 



months, in one case 16 months. The cinders resulting from these 

 fires are still very conspicuous. These shales furnish no fossils, 

 except a few vegetable impressions resembling a Catamites, and 

 some very indistinct impressions of shells. Pyritous nodules and 

 septaria are quite common. Capt. Maiden, of Thunder Bay 

 Island, gave me a specimen of the latter, in the shape of a very 

 oblate ellipsoid, 14 inches in its greater diameter and 3 in the 

 lesser. 



At Squaw Pt., on the main land south of the island, near the 

 residence of the old Indian Chief, Zwanno Quaddo, the black 

 slates are found in place, in a cliff 10 feet high. The exposed 

 surfaces are very much discolored by oxide of iron. 



On the opposite side of the State the black shales are seen at 

 the south-east extremity of Mucqua Lake, in Emmet county; on 

 the north side of Pine Lake, (sec. 3, T. 33 N., 1 W.); near the 

 outlet of Grand Traverse Bay, (sec. 3, T. 32 N., 9 W.), and a 

 few miles south of there, and again near the head of Carp 

 Lake, in Leelanaw county. The greatest observed thickness in 

 this part of the State is 20 feet. 



On the east shore of Grand Traverse Bay, nearly opposite 

 the north end of Torch Light Lake, is a bed of green shale oc- 

 cupying a position above the black shale. It is rather a soft, 

 semi-indurated clay, traversed by bands of lighter color, appar- 

 ently calcareous. 



No rocks have anywhere been seen reposing upon the black 

 or green shales. 



From Sulphur Island, in Thunder Bay, the black shales pass 

 under the bed of Lake Huron toward the south-east, and 

 emerge at Cape Ipperwash, on the Canadian shore. From here 

 they are traced to the township of Mosa, in Middlesex county, 

 and, from their occurrence at Enniskillen and other localities in 

 the vicinity, they may be regarded as occupying the triangle 

 embraced between the two belts of Hamilton rocks, before 

 referred to, and the National boundary line. This triangle 

 would be the thinning out corner of the great basin which 

 forms the Lower Peninsula of Michigan. 



