52 LOWER PENINSULA. 



compact spots, while the surrounding hghter-colored rock mass has 

 a certain degree of porosity. Lucina elliptica was the only fossil 

 noticed. About 12 feet above the vertical bluffs is the level of 

 the first terrace, the intervening space being apparently made up 

 of limestone ledges of similar character to the lower beds. On 

 this first terrace rises a second, its elevation above the first being 

 about 25 feet. This likewise is formed of a continued series of 

 lime-rock ledges, and these represent the quarry rock of the so- 

 called Crawford's marble quarry. 



The rock of this second bluff is deposited in uneven beds of quite 

 unhomogeneous structure, not suitable for large blocks, and 

 not susceptible of an equal polish ; some portions are porous, with 

 dull, earthy fracture. Nearly the entire bulk of these rock beds is 

 composed of several species of Stromatopora, Str. monticulifera, 

 Str. Wortheni, and Str. textilis. Other fossils observable are Cyatho- 

 phyllum profundum, Eridophyllum simcoense (similar to), Favosites 

 (various forms), Atrypa reticularis, Strophodonta erratica, Lucina 

 elliptica, Lucina sp. nov. and Orthoceras. The top of the second ter- 

 race is covered by drift deposits. From this level, undulating high- 

 lands extend southward, meeting the highlands surrounding the 

 head branches of Thunder Bay River. Rock beds similar to 

 those of Crawford's quarry, or somewhat higher beds, are, all over 

 these high plains, not very deeply covered by drift, and are fre- 

 quently denuded. The principal denudations of the rock are 

 confined to certain belts striking in a southeast and northwest 

 direction. One of these belts may be indicated by a line drawn 

 from the north end of Long Lake to the mouth of Oqueock River 

 in Hammond's Bay ; another limestone belt can be followed 

 from the head branches of Thunder Bay River (north branch) to 

 Rainy River and Sheboygan Lake. 



The surface rock most frequently seen on these high plains is light- 

 colored, of crystalline grain, and principally contains the already- 

 mentioned species of Stromatopora; a species of Diphyphyllum 

 is also quite common (Diphyph. rectiseptatum). In some localities, 

 shaly beds, intermediate between the limestones, are very fossilifer- 

 ous. On McArthur's farm, 8 miles southwest of Crawford's quarry, I 

 collected from the material thrown out in digging a well, Favosites 

 Hamiltonensis, Favosites digitatus, Cyathophyllum profundum, 

 Chonophyllum ponderosum, Aulopora conferta, Stromatopora 



