48 WISCOJS^SIJT ACADEMY SCIENCES, ARTS, AND LETTERS. 



gives 3,949 feet for the thickness of the bed. The sandstona is red- 

 dish, fine grained and argillaceous. Flakes and concretions of in- 

 durated reddish clay are of frequent occurrence in the layers. The 

 most northern exposure is near Chase's dam on section 36, town 

 44, range 13, west. Above here, on the St. Croix, no rock in place 

 has been found. Two localities of southward dipping sandstone 

 are known in Ashland county — the first at Lehigh's, on Bad 

 River, where the thickness is 2,000 feet, and the second twelve 

 miles southwest from Lehigh's — at Welton's, on White River — 

 where onl}' a few hundred feet are exposed. Owen, in an old execu- 

 tive document, reports southward dipping sandstone, at the head 

 of White River, twenty miles still farther southwest. From here 

 it is only 32 miles in the direction of the general trend of the for- 

 mation to the southward dipping sandstones of the St, Croix, at 

 Chase's dam. It is therefore probable that the bed extends entirely 

 across the State from the St. Croix River to Lake Superior, enter- 

 ing the Lake at the mouth of the Montreal River. Owen reports 

 southward dipping sandstones in Minnesota, on Kettle River, six 

 miles above the falls of that stream. These exposures may be a 

 westward continuation of the same bed. 



The southward dipping sandstones and shales, form with the 

 northward dipping sandstones, shales and conglomerates, a syncli- 

 nal extending entirely across the State, the opposite edges of which 

 approach on the west within four miles of each other, but on the 

 east are separated by eight or nine miles. From this fact and oth- 

 ers to be given, the conclusion may be assumed that the northward 

 and southward dipping beds are the equivalents of each other. As 

 both are largely represented on Bad River, and, moreover,"as it was 

 upon that stream that the southward dipping bed was first ob- 

 served, I propose the name of Bad Riva' sandstone for these, the 

 upper beds of the copper-bearing ^series, 



4:^ Lake Superior sandstone.— "Ihi^ term is generally employed 

 to designate the reddish aluminous sandstones which nearly every- 

 where border the south shore of Lake Superior. Thej' also form 

 the basement rock of the Apostle Islands. They have never been 

 found in a tilted condition/" The interesting question of their age 

 has been ably discussed by numerous writers upon the geology of 

 Lake Superior. Without commenting upon the opinions which 

 have been advocated upon this subject, some referring them to the 



