40 WISCONSIN" ACADEMY SCIENCES, ARTS, AND LETTERS. 



NOTES ON THE GEOLOGY OF NORTHERN WISCONSIN. 



BY E, T. SWEET, 11. S. 

 Assistant on the Geological Survey of Wisconsin. 



During the summer months of 1873 and 1875, I was occupied, 

 mainly in northern and northwestern Wisconsin, assisting in the 

 prosecution of the field-work of the State Geological Survey. The 

 greater part of the season of 1873 was devoted to an examination of 

 the Penokie Iron Range, including incidental observations upon the 

 geology of Ashland county, iinder the direction of Professor Ir- 

 ving. Late in the season I received instructions from our la- 

 mented chief geologist. Dr. Laphara, to examine and report upon 

 the "Copper Ranges " of Douglas county. My visit to the northern 

 part of the State during the season of 1875 consisted of a reconnoi- 

 sance of northern Wisconsin, under the direction of Dr. Wight, 

 the State Geologist. Canoe-trips were made from St. Croix Falls, 

 nearly to the source of the St. Croix river; from the head of the 

 Chippewa river to Chippewa Falls; from Jenny up the Wisconsin 

 and Pelican Rivers, and from Post Lake down the Wolf River to 

 Shawano. The total distance traveled by the party, during two 

 months, mainly upon these streams, was about 700 miles. 



The main results obtained in Ashland and Douglas counties the 

 first season, have already been made public by Professor Irving, 

 through the second volume of the Transactions of the Academy. I 

 wish to call particular attention to the Professor's paper on " Some 

 Points in the Geology of Northern Wisconsin," and to the conclu- 

 sions reached by him ; for, in many respects, this paper may be con- 

 sidered merely a supplement to that. His general conclusions will 

 be accepted and quoted without reiterating the proof upon which 

 they are based. Several points alluded to in his paper, I wish to 

 still further elaborate in connection with the presentation of facts 

 which were observed for the first time during the reconnoissance. 

 In this paper I shall especially discuss the main features in the ge- 

 ology of the region immediately bordering the St. Croix river from 

 St. Croix Falls to the head of that stream, and shall also frequently 



