54 WISCONSIN" ACADEMY SCIEIs^CES, ARTS, AXD LETTEES. 



1. The westward extension, to the St. Croix River, of all the for- 

 mations found north of the Penokie Range to Lake Superior. 



2. If the iron bearing belt extends westward, it doubtless follows 

 the southern boundary of the Cupriferous formation. It would 

 therefore cross the St. Croix River some distance below the mouth 

 of Snake River. Then, in the neighborhood of a line drawn from 

 the mouth of Snake River to Penokie Gap, one would expect to 

 find indications of the Huronian magnetic schists. Iron ore is re- 

 ported in place, at several localities in the vicinity of this line. 

 Explorers report its occurrence near the southern end of Long 

 Lake, also on section 18, town 43, range 19 west, and from the 

 northern part of Burnett county. On the original survey plat of 

 town 38, range 19 west, I find on section 19, topographical lines 

 indicating a ledge, and the words '" iron ore." The locality has not 

 been examined by members of the Geological Survey, 



3. The non-occurrence of ranges or marked ridges in the St_ 

 Croix country may be cited in this connection, and reasons given 

 why they should not be expected. In the eastern part of Ashland 

 county the high ridge formed by the Penokie range is due to the 

 nearly vertical dip of the strata. As the formation of northern 

 Wisconsin extend westward the dip gradually decreases and they 

 more nearly approach horizontality. Brooks reports the dip of the 

 Huronian schists in the vicinity of Black River in Michigan, some- 

 times as great as 90"^. At the gorge of Tyler's Fork I found the dip 

 75'^ to the northwest. At Penokie Gap the dip is 6Q° while at At- 

 kins Lake the inclination is onl}' 45° to the northwest. The upper 

 members of the Copper-Bearing series, which have an almost verti- 

 cal dip on the Montreal River and at the mouth of Tyler's Fork, 

 have only a slight dip to the northwest on the St. Croix River. At 

 Lehigh's, on Bad River, the southward dipping sandstones incline 

 38° to the southeast. At Weiton's the dip is 25°, while on the St. 

 Croix it is but 14° to the southeast. As the formations approach 

 the St. Croix they do not form hold ridges^ hut cover a much ivider 

 extent of territory than in the eastern part of the State, and conse- 

 quently the opposite edges of the synclinal are found much closer 

 to each other than farther eastward. 



4. The occurrence of small angular boulders of magnetic rock 

 and iron ore in the drift at numerous localities in Polk and Bur- 

 nett counties. 



