WIXXEBAGO COUNTY. 89 



in lithological characters, to the Galena. The elevations here are 

 capped with the latter rock. The Sugar river hills are rock ribbed 

 with the division of the Trenton, now under consideration. 



The fossils noticed in the railroad cuts near Shirland, were so nuraer- 

 ons as to make their description at this time too tedious. They were 

 mostly small and fragmentary. Some of the thinner and more shaly 

 strata are covered with shells, fragments of trilobites, stems of the en- 

 crinites, and pieces of corals, so thick as to resemble masses of fossils 

 stuck together by some adhesive paste. The same limestones at Dixon 

 are exactly similar in appearance. 



The Buff Limestone. This is an unevenly bedded, somewhat argilla- 

 ceous or clayey dolomite. It is, for the most part, of a light-yellowish 

 or brownish color, shading into blue towards the bottom of the quarries; 

 is not very homogeneous in composition or stratification, presenting in 

 some of its layers an earthy and in some a crystaline appearance. In 

 every outcrop, worked to any considerable extent, the lower layers be- 

 come quite massive, and of a dark-blue color. When first taken out 

 this blue stone presents a beautiful appearance, and no materials make 

 handsomer mason work; but when exposed to the weather for some 

 length of time, the dark, rich, blue color fades into a. dirty, whitish-blue, 

 not so beautiful as the original color. This rock, however, makes a 

 good building stone, but, on account of its earthy base, does not burn 

 into a good lime. But a limited portion of the county is underlaid by 

 this formation. If from two points in the boundary line between Wis- 

 consin and Illinois, distant from Bock river on each side three or four 

 miles, we extend two lines southward, following the general course of 

 the river, but drawing gradually nearer together until a point in the 

 center thread of the stream was reached, one or two miles south of the 

 north line of Harlem township, the tongue of land thus inclosed would 

 represent this portion. The chief outcrops of the formation, and in fact 

 the only ones where it can be satisfactorily examined, are at Beloit, a 

 short distance within the. State of Wisconsin, and at Bockton, about the 

 middle of our tongue-shaped strip of laud. The quarry at this latter 

 place is opened on the north face of a low range of hills, ranging along 

 the south bank of Bock river, and distant one mile from the village. 

 The outcrop, as here worked, is forty-five feet thick, and answers well 

 to the above description, except that the upper ten or fifteen feet re- 

 semble beds of passage into the overlying division. This outcrop, to- 

 gether with its closely resembling ones at Beloit, in Wisconsin, and at 

 AVinslow, in Stephenson county, and at Martin's Mill, in Wisconsin, ex- 

 hibits about the following section : 



13 



