58 LOWER PENINSULA. 



fracturing limestones, intcrlaminated with shaly seams, and fossi- 

 liferous in nests. The Hmestone with smooth fracture Hke 

 lithographic stone contains 98 per cent of carbonate of lime, i per 

 cent carbonate of magnesia, and i per cent of insoluble silicious 

 matter. Superimposed on these beds are drab-colored, porous 

 dolomites, with Stromatopora monticulifera, Stromatop. Wor- 

 theni, Cyathophyllum profundum, Favosites Hamiltonensis. The 

 outcrop is at this horizon interrupted ; it is the place where 

 the fossiliferous blue shales of the other sections should be 

 found, with the incumbent fossiliferous dolomites. A short 

 distance behind the top of the bluffs which exhibit this section, 

 a second terrace rises, which is composed of dark, drab-colored, 

 cr}''stalline dolomites, identical with those composing the rock 

 bluffs of Khagashewung Point, or with the buff magnesian beds of 

 Prof. Winchell. 



Khagashewung Point, for more than a mile's length, is lined 

 with vertical rock bluffs about 15 feet high. The lowest strata 

 exposed along this point are light-colored, smooth-fracturing 

 limestones, intcrlaminated with thin seams of shale, and with a 

 bed of a crystalline limestone almost entirely composed of Cri- 

 noid joints. Fossils are not numerous in them, and are of the 

 usual kinds found in the other outcrops. Above them are some 

 beds of a blue, argillaceo-arenaceous lime rock, containing many 

 specimens of Cyathophyllum profundum, Favosites Hamiltonensis, 

 Cystiphyllum Americanum, and Atrypa reticularis. Then follow 

 light-colored limestones with earthy fracture and of thinly lami- 

 nated structure, linear carbonaceous seams pervading them in the 

 bedding plains. Their thickness is only a few feet, and they resem- 

 ble the laminated, dolomitic beds at the foot of the Petosky bluffs, 

 inclosing the same fish-bones and a few stems of Favosites. The 

 higher part of the Khagashewung cliffs is formed by layers of a 

 porous, crystalline dolomite, of a brownish yellow color, in thick, 

 homogeneous beds, of variable finer or coarser grain. Fossils are 

 generally rare, but in certain seams casts of Brachiopods, or dis- 

 persed specimens of Favosites, Cyathophyllum profundum, etc., are 

 noticed. Other beds are a coarsely crystalline, crinoidal limestone, 

 with many other fractured shells besides the Crinoid joints. 

 Atrypa, Spirifer, Cyrtina, Strophodonta, Rhynchonella, are the rec- 

 ognizable forms ; Proetus and Phacops are likewise to be found. 



