THE STUEGBON RIVER TONGUE. 459 



the N. quarter post of sec. 13, T. 42 N., R. 29 W., and westward to near the 

 southwest corner of sec. 12, T. 42 N., R. 30 W. From this pomt the Hue 

 leaves the Sturgeon River tongue, curves southward, and returns east on 

 the north side of the Felch Mountain tongue. The eastern boundary of the 

 Sturgeon River Algonldan area is even less definitely determinable than its 

 southern boundary, because of the thick drift covering the rocks. This 

 boundary is placed at about the east lines of sees. 6 and 7, T. 42 N., R. 27 W., 

 because just east of this line, in the NW. ^ sec. 5, ledges of Paleozoic 

 limestone occur. The northern boundary is the most indefinite of all. 

 The southern portions of T. 43 N., Rs. 28, 29, and 30 "W., are so deeply 

 drift covered that but few ledges can be found in them, and these are widely 

 separated. In sec. 6, T. 42 N., R. 27 W., and in sees. 13 and 24, T. 43 N., 

 R. 29 W., are exposures of granite. These, so far as is known, mark the 

 southern limit of an Archeau area which stretches some miles northward 

 and separates the Sturgeon River fragmentals from those of the Marquette 

 district. The line marking the northern boundary of the Sturgeon River 

 tongue begins at the southeast corner of sec. 6, T. 42 N., R. 27 W., and is 

 assumed to run a few degrees north of west from this point until it reaches 

 the west line of R. 29 W., where it turns north. 



Between the northern and the southern boundaries of the sedimentary 

 area as defined, and in the midst of the sediments, are two areas of granite, 

 the rock of one of which is unquestionably, and that of the other presum- 

 ably, older than the conglomerates within the tongue. The best defined of 

 these two areas lies in the northern portions of sees. 7 and 8, T. 42 N., 

 R. 28 W., and sec. 12, T. 42 N., R. 29 W. It measures about 2 J miles in 

 length and less than one-half mile in width. The extent of the second 

 area can not be so accurately outlined. It occupies about three-fourths of 

 a square mile and is entirely within sec. 3, T. 42 N., R. 29 W. 



LITERATURE. 



But few references to the existence of fragmental rocks in this portion 

 of the Upper Peninsula of Michigan can be found in the literature of the 

 region. 



The early United States surveyors^ reported the occurrence of talcose 



' General observations upon the geology and topography of the district south of Lake Superior, 

 by Bela Hubbard: Thirty-first Congress, first session, Executive Documents, 1849-.50, Vol. Ill, No. 1, 

 pp. 846, 847, 848, 855. 



