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 locaUties bearmg on tlie same conclusion. It is only necessary 

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

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

 Oecomes necessary to believe that tlie surrounding Ingh-level sandstone, apparently 

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

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

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



Sandstone is quarried, of excellent quality, at several places near Baraboo. 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 sis-feet face, showing heavy and regular beds of 

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

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

 splits easily into tliin 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. 





'.isttme.. 



Map and SEOiroN SiiowiNS the Kelativb Posrrmits oP the Book OuTcnopa at Wood's, nuab 



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 hmestone closely like that at 

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

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

 per cent, of insoluble ingredients, which are aluminous rather than sihcious. In places 

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

 oliserved. On the south face of the same ridge, and on the south hne of Sec. 10, is a 

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

 surfaced, subangular grains of glassy quartz, and contams many pebbles of red 

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



