42 WISCOJ^SIN ACADEMY SCIENCES, ARTS, A^'D LETTERS. 



east and west. The clip is always at a high angle either to the 

 north or south. 



The Laurentian rocks of Wolf River are very uniform in charac- 

 ter. From Post Lake to Keshena, a distance of about seventy-five 

 miles, the rocks are all exceedingly coarse grained feldspathic gran- 

 ite. The crystals of orthoclase are often several inches across. 

 Biotite, a variety of black mica, appears to be a characteristic of 

 these rocks. At localities it is the exclusive variety of miaa found. 

 At Post Lake dam, on section 9, town 33, range 12 east, a ledge of 

 hornblendic schist gives a strike of north, fifty degrees east. With 

 this exception no undoubted strike or dip was observed in the rocks 

 in the vicinity of Wolf River. A few miles above Keshena the sur- 

 face of the granitic fields has been worn by glacial action into 

 knolls and knobs which present the characteristic appearance of 

 " Roches Montonnees." Large boulders of uniform, coarse grained 

 granite are of frequent occurrence in the channel of Wolf liver 

 from Post Lake dam to Keshena. Many boulders also, of immense 

 size have been transported from this region, far to the southward, 

 aud deposited in Waushara and adjoining counties. 

 % "^ Huronian. — Several new and interesting points showing the re- 

 lationship between the Laurentian and Huronian formations were 

 observed at Penokie Gap, by Mr. C. E. Wright, of Marquette, Mich- 

 igan, and myself, during the season of 1875. We spent nearly three 

 daj's at the " Gap '' and succeeded in making several important ad- 

 ditions to the geological section of the " Range," taken two years 

 before at that point, by Professor Irving and myself. The section 

 referred to accompanies Professor Irving's manuscript report on 

 the Penokie Range now in the office of the Secretary of State. It 

 extends from the fine grained white quartz and siliceous slates on 

 the south to the massive diorites on the north, a distance across the 

 formation, at right angles to the dip, of about four thousand feet. 

 Mr. Wright and myself extended this southward a short distance to 

 the Laurentian gneiss and granite, and northward over two thou- 

 sand feet, probably to the lowest member of the Copper-Bearing 

 Series. 



■ The junction between the Laurentian and Huronian is in the 

 southern part of section 11, town 44, range 3 west. At this point 

 Bad River passes through a narrow gorge having nearly vertical 

 walls on either side. In the left or northern wall of the gorge, fine 



