14 REPORT OF THE 



A. Yellow and greenish sandstones. (lb.) The sand- 



stones XVII are supposed to be equivalent to the 

 Ohio "Conglomerate" and "Waverly Sandstone.* 

 (Hubbard, 1841, p. 132.) 

 XVI. Clay Slates and Flags of Lake Huron, 180 ft. (Hub- 

 bard, 1841, p. 136.) Divided into 



B. Argillaceous sandstone, alternating with sandstone 



and clay slates. 



A. Blue clay slates and flags, with alternating gyp- 



sum beds and gypseous marls. These two (A and 

 B) constitute the "Upper Salt Rock" (Hubbard, 

 1841, p. 133). The gypsum of Grand Rapids is 

 placed here by Hubbard, (1841, p. 133). 

 XV. Pt. au Gres and Manistee* limestone (Douglass, 1841, 



pp.102, 103). 

 XIV. Soft, coarse-grained sandstones, 230 ft. (Hubbard, 

 1841, p. 133.) Pierced at Grand Rapids, in the salt 

 well of Lucius Lyon. The "lower salt rock" of 

 Ohio, Va. and Mich. (lb. 133.) 

 XIII. Black bituminous, aluminous slate, with pyrites (Hub- 

 bard, 1841, p. 134). 



B. Light blue, argillaceous (Douglass, 1841, p. 102). 

 A. Black, containing p3 r rites. (lb.) 



XII. Limestone of Lake Erie, (Hubbard, 1839, pp. 88, 105; 

 1840, p. 83 ; 1841, p. 134). Subdivided as follows: 

 D. Corniferous limestone, (Douglass, 1841, p. 102). 



C. Thunder Bay and Little Traverse Bay limestones, 



(Douglass, 1841, pp. 112, 103). 



(/) Blue silicious limestone, (Douglass, 1841, p. 



100.) 

 (e) A confused mass of broken fossils, imbedded 



in clay. (lb.) 

 (d) Vesiculated chert, colored with iron. (lb.) 

 (c) Flaggy limestone in very thin layers. (lb.) 



♦The liimstono referred to by Douglass seems to bo rather on tho Muskegon than on th» 

 Majiistee river, which is many miles further north. 



