46 WISCOJfSIK ACADEMY SCIENCES, ARTS, AND LETTERS. 



tend. Neither has their relationship to the Lake Superior Copper- 

 Bearing System yet been made out. The bedding, if it exists, is 

 very indistinct. Across the formation at right angles to the ap- 

 parent strike, the distance is between four and five miles. In lith- 

 ological character tire rock differs from any I have noticed in the 

 Lake Superior region. It is usually very fine grained, dark gray 

 in color, and is apparently made up of feldspar, hornblende and 

 quartz. Some varieties are porphyritic, other anwgdaloidal. At 

 the falls and dalles of the St. Croix these rocks are largely exposed. 

 A mine at Taylor's Falls, near the dalles, has been worked to a con- 

 siderable extent in this rock for metallic copper. It is said en- 

 couraging results have been obtained. 



After leaving the St. Croix Falls range, nothing more is seen of 

 the copper-bearing rocks along the river to a point thirty miles 

 north from the Falls. A short distance north of the mouth of 

 Snake River Cupriferous rocks again come in. They are mainly 

 melaphyrs and amygdaloids, and are overlaid by horizontal beds of 

 light colored Potsdam sandstone. A few miles to the north, con- 

 glomerates and reddish shales conformably overlie the Cupriferous 

 strata. The dip, so far as can be made out, is slight, and to the 

 northwest. The conglomerate is heavily bedded, but does not cover 

 the melaphyrs and amygdaloids at all points. It appears rather to 

 fill pockets and depressions in the underlying rocks than to be intr- 

 stratified with them. The pebbles of the conglomerate are usually 

 very large, some of them being over a foot in diametor. They 

 have all evidently been derived from the underlying Cupriferous 

 rocks. The matrix consists of reddish grains of quartz, similar to 

 the Lake Superior sandstone. A short distance above the mouth 

 c>f Kettle River, the most northern exposure of the Kettle Riyer 

 range is found. Across the formation at right angles to its trend, 

 the distance is four and one half miles. Copper has been discovered 

 and locations have been marked upon this range near the St. Croix 

 River. The conglomerates and shales associated with the melaphyrs 

 and amygdaloids of the Kettle River range occupj'- the same strati- 

 grapical position, and are in every respect, except in the degree of 

 inclination, similar to those of the copper range of Ashland county, 

 exposed on Bad River at the mouth of Tylers' Fork. On Bad 

 River the dip is nearly vertical to the northwest, while on the St. 

 Croix it is but a few degrees in the same direction. Between these 



