STATE GEOLOGIST. 69 



ence. Mr. Francis showed me here excellent crops of Indian 

 eorn, potatoes and oats. 



9. — Hamilton Group. 

 s On the east side of Thunder Bay Island, the rocks of the 

 Helderberg Group are seen overlain by a black bituminous 

 limestone, abounding in Atrypa reticularis, and numerous other 

 Brachiopods allied to the types of this group. The locality 

 furnishes, also, two or three species of trilobites, a Favosites, 

 a targe coral allied to Acervularia and some fish remains. The 

 rock breaks in every direction, and abounds in partings of dark 

 shaly matter. 



The same beds are again seen at Carter's quarry; two or 

 three miles above the mouth of Thunder Bay river, and here it 

 contains the same fossils. It is seen again on the south shore of 

 Little Traverse Bay, replete with Brachiopods and Bryozoa, and 

 is here eighteen feet thick. It is overlain by two feet of dark 

 chocolate colored, compact, argillaceous limestone, much shat- 

 tered, and abounding in Cyathophylloids and other corals, 

 which, in turn, is surmounted by 14 feet of a limestone varying 

 from calcareous and crystalline to argillaceous, in beds from 2 to 

 24 inches thick. The whole series is completed by 6 inches of 

 black shale. 



The exact order of superposition of all the rocks constituting 

 the Hamilton Group, has nowhere been observed. The bluff at 

 Partridge Point, in Thunder Bay, is believed to come in next 

 above the bituminous limestone of the localities just cited. The 

 rock here is at bottom, a bluish, highly argillaceous limestone, 

 with shaly interlaminations, the whole wonderfully stocked 

 with the remains of Bryozoa and not a few encrinital stems. 

 No calices of Encrinites, however, could be found, except two 

 Pentremites picked up along the beach, and one Cyathocrinoid 

 found in place. Above these beds, which are but five feet thick, 

 occurs a mass of blue shale, six feet thick, calcareous in 

 places, and irregularly interstratified with b'ue, argillaceous 

 limestone. It contains Bryozoa, Oyathopbyllidae and Trilobites. 



