THE LOWER SILURIAN ROCKS. 



595 



Eiky limestone meets with considerable difficulties, and has quite important conclusions 

 depending upon it. This subject is discussed briefly in another place, in connection 

 with facts from other localities bearing on the same conclusion. It is only necessary 

 to say here that the fossils from this limestone are regarded by Mr. Whitfield as cer- 

 tainly not lower than the Lower Magnesian, and that, if we receive this reference, it 

 becomes necessary to believe that the surrounding high-level sandstone, apparently 

 without doubt of the Potsdam series, had been extensively eroded before the deposition 

 of the limestone, and that the latter forms merely a nest lying upon the -eroded surface 

 of the older sandstone, as indicated by the dotted line of Fig. 48. 



Sandstone is quarried, of excellent quality, at several places near Bare boo. One of 

 these is on the south side of a ridge on the N. E. qr. of Sec. 1, T. 11, R. 6 E., just east 

 of the village. The quarry here has a six-feet face, showing heavy and regular beds of 

 moderately fine-grained, white, non-calcareous sandstone (1230), which is marked with 

 fine brownish lamination lines, is made up of glassy, subangular quartz grains, and 

 splits easily into thin slabs. Another and much larger quarry is opened on the 

 " stossed " point of a ridge, southwest of Baraboo, on the N. E. qr. of Sec. 2, T. 11, R. 

 6 E. The end of the ridge is planed and scratched on a large scale. The total thick- 

 ness seen is about thirty feet, the sandstone being white, fine-grained, firm, and obtain- 

 able in large, well-shaped blocks. In places, a net- work of thin quartz seams is notice- 

 able. This stone, as well as that quarried at other points in the Baraboo valley, is an 

 unusually good sandstone to come from the Potsdam, series, much of which is so loose- 

 and friable, or badly colored, as to have no value as a stone for building. 



FIG. 49. 



MAP AND SEJTION SHOWING THE KELATIVB POSITIONS OF TIIE EOCK OUTCROPS AT WOOD'S, NKAR 



BARABOO. 



On the N. W. qr. of the S. W. qr. of Sec. 10, T. 11, R. 6 E., on Mr. Joseph W. 

 Wood's land, is a small quarry, on the point of a ridge, of limestone closely like that at 

 Eiky's quarry in Greenfield. The rock (1260) is brownish, porous, rough-surfaced, and 

 minutely crystalline, with, in places, a concretionary structure, and contains only 9.03 

 pec cent, of insoluble ingredients, which are aluminous rather than silicious. In places 

 an indistinct columnar, coral-like structure is noticeable, but no undoubted fossils were 

 observed. On the south face of the same ridge, and on the south line of Sec. 10, is a 

 long ledge of fine-grained, reddish-brown sandstone (1262), which is composed of rough- 

 surfaced. subangular grains of glassy quartz, and contains many pebbles of red 

 quartzite. numerous Scolithus borings, and fine, large impressions of Dicellocephalus 



