354: GEOLOGY OF EASTERN WISCONSIN. 



ness, constituting three terraces, rising in succession from the lake shore. The ledges 

 here are extremely fossiliferous, and this locality is already known in the literature of 

 the science. The uppermost ledge is capped by a few layers of the Racine limestone. 

 South of Jacksonport, along the lake shore, the Upper Coral limestone is again ex- 

 posed, presenting a thickness of twenty feet, with its usual characteristics and abundance 

 of fossils. 



In the vicinity of Sturgeon Bay, several exposures, both of the Upper and Lower beds, 

 occur. In Sec. 9, there are several shght outcrops of the upper strata, which are here, 

 as usual, quite cherty and contain an abundance of silicified fossils, among which the 

 coralline forms predominate. In Sec. 5, near the village of Sturgeon Bay, the upper 

 poi-tion of the Coral beds have a slight exposure, overlaid by a few of the Racine beds. 

 The junction between the two is here sharp and well defined, the uppermost layers of 

 the Coral beds being highly fossUiferous, a fact which does not seem to be universally 

 true, as at several other points the beds lying immediately beneath the Racine lime- 

 stone ai-e comparatively free from fossils. North of the village, near the mill, the Lower 

 Coral beds are shown imperfectly, but in considerable thickness. Still farther north, 

 along the cliffs facing the bay, at various points, partial sections of the same beds are 

 exposed. On the opposite side of the bay are numerous partial exposures of the Lower 

 Coral beds overlying the Byron beds. Following the outcrops of the formation south- 

 ward, Greening's ledge, in the town of Forrestville (S. W. qr. Sec. 17), is worthy of 

 note for the remarkable abundance of fossils which it presents. Passing by several 

 minor exposm-es, we find, on Scarboro creek, in the town of Casco, and in Sec. 28 of the 

 town of Pierce (T. 24, R. 24), the Upper Coral strata presenting their usual thin, uTeg- 

 ular, cherty outcrops, and characterized by an unusual abundance of well presened 

 sdicified fossils. The latter locality is remarkable for the great number of Pavositoid 

 corals, large masses of Si/ringopora, and frequent specimens of Strombodes, in associa- 

 tion with an abundance of the more usual forms. In Sec. 14, in the town of Kewaunee, 

 at the mill of Mr. Stramsky, tiie uppermost layers of the Coral beds are found immedi- 

 underlying the Racine limestone. They are here more homogeneous and less cherty 

 than at most localities to the northward, and much less fossiliferous than the corres- 

 ponding beds at Sturgeon Bay, only five or six species being observed. In the valley of 

 West Twin river, several notable exposures of this formation occur. In Sec. 28, town of 

 Gibson, a vertical thickness of about forty feet, belonging to the lower division, is ex- 

 posed. The upper portion of the ledge consists of very heavy beds of coarse, rather soft 

 dolomite, characterized by fine specimens of coral. The lower portion of the ledge con- 

 sists of a harder and more compact rock of finer texture, very prolific in Pentamerus. 

 In the vicinity. of the junction of Mud creek with the West Twin river, particularly in 

 Sec. 13, Cooperstown, ledges that appear to represent the transition from the Lower 

 Coral beds to the Byron beds find ample exposure. The following section is observed 

 near the center of Sec. 1-3. 



1. At the top, a broken, grajdsh white dolomite, mottled with pinkish 



red, of porous, rather hard, brittle, crystalline texture and uneven 

 fracture, in beds of 18, 11J^2, 15 and 133^ inches, respectively. The 

 lower layers are more compact than those above 4 ft. 10 in. 



2. Harder laminated dolomite, of slightly porous textm-e, gray, lined 



with pink 1 ft, 54 in. 



3. Similar to No. 1, but more coarse and porous in texture, and rougher 



in general aspect 2 ft. 2^ in. 



4. Similar to No, 2, but not distinctly laminati.-d. In beds of 7}4, 12 and 



] 1 inches respectively 2 ft. 6i in, 



b. Rather soft, granular dolomite, of sandy appearance, streaked with 



white and yellow, and distinctly blotched with copper red 6 in. 



