HAMILTON GROUP. 53 



Wortheni, Fistulipora, Atrypa reticularis, Pentamerus costatus, 

 Streptorhynchus, Strophodonta concava, Strophodonta nacrea, 

 Productella navicella, Cyrtina Hamiltonensis, Spirifer granu- 

 liferous, Spirifer mucronatus, Lucina elliptica, several casts of 

 Gasteropods, and dermatic plates of fishes. A continuation of 

 the same range of rock exposures of the lower division of the Ham- 

 ilton group is seen on Rainy River, 4 miles from its entrance into 

 Black Lake (Sheboygan Lake), and in the rock bluffs facing Black 

 Lake in Town. 35, R. 2, east, Sect. 7. In both localities, from 30 to 

 40 feet of strata are exposed. Highest are light-colored limestones, 

 with Stromatopora and Cyathophyllum profundum, 20 feet in 

 thickness, and somewhat variable in the structure of the single beds. 

 Below these are about 12 feet of calcareous shales full of well-pre- 

 served fossils, viz. : Cyathophyllum profundum, Cyathophyllum 

 Houghtoni, Cyathophyllum resembling C. cornicula, Cystiphyllum 

 Americanum, Favosites digitatus, Favosites Hamiltonensis, Za- 

 phrentis, Syringopora nobilis, Fistulipora, Chsetetes and other 

 Bryozoa, Atrypa reticularis, Spirigera concentrica, Strophodonta 

 demissa, Strophodonta concava, Spirifer zigzag, Spirifer granulifer- 

 ous, and fragments of Proetus. Lowest are hard, smooth-bedded 

 limestone strata containing few fossils. 



Westward from Black Lake, the environs of Mullett Lake and 

 Burt Lake, and all the district north of them, up to the Straits of 

 Mackinac, are deeply covered with drift deposits, with the ex- 

 ception of the foot of the promontory at McGulpin's Point, which, 

 as we have seen before, presents the upper strata of the Helder- 

 berg group. Much the larger portion of this district is covered 

 by hard-wood timber and has a rich soil, which has attracted a good 

 many settlers, and amply rewarded the labor bestowed on it. North 

 of Burt Lake and in the vicinity of Turtle Lake, the land is sandy 

 and poor, covered by pine forests, but toward Little Traverse 

 Bay it becomes much better again. The soil in the vicinity of 

 Sheboygan is a heavy but fertile clay. The clay of the drift 

 formation furnishes an excellent material for brick manufacture. 

 The north shore of Little Traverse Bay has no rock exposures. 

 High drift bluffs ascend from the lake, and terrace by terrace the 

 land rises into a plateau of about 250 feet elevation, which extends 

 from the bay up to Cross village. 



The south shore of the bay ascends likewise in terrace form, 



