34:6 GEOLOGY OF EASTERN WISCONSIN. 



Fossils. These are very rare. At Butler's qimrry, in the town of 

 Byron, Leperditia fonticola is abundant, this being its typical local- 

 ity. Fucoidal impressions are occasionally met with, and an undeter- 

 mined ZapJirentis was found near Sturgeon Bay. 



Thickness. The greatest observed thickness, not including the 

 transition beds above, is 110 feet; incbiding that portion of the transi- 

 tion beds most allied to this division, its maximum thickness would 

 reach perhaps liO feet. 



DistrihMion. The formation presents so great a degree of uni- 

 formity that local sections and descriptions will be unnecessary. 



In delineating the outcroppings of the beds below, we were carried 

 northward to near the extremity of the peninsula east of Green Bay. 

 We may secure continuity of thought and save ourselves mental trans- 

 portation by taking up the distribution of this division at that point. 



It was stated that at Little Sturgeon Bay, the Mayville beds dipped 

 down to near the water's edge. On doing so, they are at once sur- 

 mounted by the Byron beds, in full force. These form a series of 

 bold, picturesque cliffs, extending to the extremity of the peninsula. 

 Two of these cliffs stand like pillars of Hercules, at the mouth of Big 

 Sturgeon Bay, and each of the harbors north of this, on tlie west side 

 of the peninsula, is guarded by at least one such Cyclopean sentinel, 

 and one stands by Death's Door at the extremity. South of Little 

 Sturgeon Bay, this formation lies a little back from the rocky escarp- 

 ment that faces the Green Bay valley, and its strata are beveled down 

 to the general surface of the country, so that it displays itself less 

 conspicuously. The belt which it occupies at the surface lies next 

 east of the Mayville beds as far south as Washington county. South- 

 east of Fond du Lac, it again comes out to the margin of the valley above 

 referred to, and forms the white cliffs in the towns of Empire, Eden, 

 Byron and Oakfield. In this region, the base of the formation is thin 

 bedded, while in the upper portion, the beds are thicker. Soutli of 

 this, the formation again recedes from the chain of ledges, and, at a 

 very unfortunate point is lost beneath the drift of the Kettle Range. 

 This drift moraine crosses the strata under question obliquely, and .ef- 

 fectually conceals them from view for thirty miles. On the other aide 

 of the range, the beds at Pewaukee are the nearest exposed rock east 

 of the Mayville beds. 



The upper strata at this point are very similar to the Byron beds 

 in color, texture and composition, but in fossils, they are closely rela- 

 ted to the Racine limestone, while the Byron beds contain but few 

 remains of any kind, and are separated from the Racine by the Coral 

 beds, containing an abundance of fossils, less closely related to the 



