GEOLOGICAL EX PLOKATIONS AND LITEKATURE. 67 



Keweeuawau aud Huroiiiau (pp. 402-409), and the nature (pp. 37-58), 

 origin (p. 144), distribution (pp. 231-233), and relations to the Penokee 

 series (p. 156) ot" the coarse grained gaJjbros which are so largely devel- 

 oped in the Bad river country of Wisconsin. 



ISRi. 



KoJilNGER (Dr. v.). Geological lieport on the Upper Peninsula of Michigan, 

 exhibiting the Progress of the Work from 1881 to 1884. Manuscrii»t copy of Part i of 

 vol. V (unpublished) of the reports of the Geological Survey of Michigan. 



Through the kindness of Dr. Romiuger, I have been furnished with a 

 transcript of that portion of this volume which refers to the pre-Keweena- 

 wan rocks. In it are included the results of certain studies made by the 

 author in the Gogebic district, between lake Gogebic and the Montreal 

 river. No maps or other illustrations accompany the volume. The head- 

 ings under which the subject-matter of the report is classified are the names 

 of certain of the several rock groups, into which the author had previously 

 divided the pre-Keweenawan rocks of the Upj^er peninsula (vol. iv, Geol. 

 Survey, Mich.), viz : the Granitic, Dioritic, Iron Ore, Arenaceous Slate, 

 and Mica-Schist groups. Under each of these headings is given the addi- 

 tional information obtained since the publication of the previous volume 

 (iv) of reports, for the entire extent of the Upper Peninsula of Michigan. 



The following are full extracts from those portions of the report which 

 apply to the Gogebic district : 



Granitic group. — . . . The granites bordering the south side of the Gogebic 

 iron range and of its continuation into Wisconsin, the Penokee range, came unKter 

 my observation during the progress of the survey. I found them iu every respect 

 analogous to the granites of the Marquette country. 



The rocks of that part are not so excessively corrugated; the upheaval lifted 

 the strata more in coutiuuous sheets, and belts of granite intrusive into the incum- 

 bent strata could not often be observed, although several granite seams cutting across 

 dioritic schists were seen about 4 or 5 miles west from the shore of lake Gogebic. 



Following the range the granite is not always found in contact with tlie .same 

 kind of strata. Locally heavy quartzite strata are in contiguity with it, the lower 

 layers of the quartzite being often reiiresented by a conglomerate filled with rounded 

 granite pebbles or by brecciated quartzose beds crowded with orthoclase crystals and 

 cemented by a wax-colored hydroraicaceous interstitial mass, which rocks resemble 

 granite so much that it is difficult to distinguish the contiguous beds. These rocks 

 correspond accurately with the rocks 1 have described in the previous report as 



