PETROGEAPHIOAL CHAEACTERS OF UPPER HURONIAN. 173 



Brooksh mucroscojncal descr'qjtioii, of rods, etc. — Coiitiiuied. 



SornMencle-schiat or gneiss, black, slaty, banded with gneissic 



layers (2453) 100 



Gneiss and mica-scliist 300 



Covered 150 



StauroUiio Diica-scliist on south, overlaid with mica-schist and 



gneiss (2455) JOO 



Covered 150 



Gneiss ■ 100 



Mica-schist _ 100 



Micaceous quartz- schist or gneiss (2381, 2457) 250 



Covered 500 



Gneiss ' 150 



He then mentions the occurrence farther up the Michig-amme River of 

 exposures of "a heavy bed of fjneiss, dipping north at a high angle," and 

 also speaks of "outcrops along the river of hornUendic and other rocks, often 

 granitic in appearance." He writes also of "chloritic and hornblende schists 

 exposed for a thickness of over 1,000 feet" at the Norway portage, farther 

 up the river. "They dip south at a high angle under the granite horn- 

 blende belt just described, and are probably the equivalents of some 

 portion of the Long Portage series on the opposite side of this synclinal, 

 althoug'h these differ from the prevailing rocks of that series in being 

 decidedly moi'e chloritic and hornblendic.^ 



It is seen from the above quotations that the general characters of the 

 rocks were, recognized by Brooks. His schists are for the most part the 

 metamorphosed sediments, and the hornblendic and granitic rocks are the 

 various basic and acid rocks which intrude them. 



Specimens from these interesting beds were collected by the Michigan 

 and Wisconsin surveys, and were described by Julien, Wichmann, and 

 Wright in lithological reports appended to the reports of those surveys.^ 



' Geology of Menominee iron region, by T. B. Brooks : Geol. of Wis., Vol. Ill, 1880, Pt. VII, p. 497. 



- Microscopical observations on the iron-bearing rocks from the region south of Lake Superior 

 by Arthur Wichmann: Chapter V of Brooks's Geology ofthe Menominee iron region, Geol. Survey of 

 Wis., Vol. Ill, 1880, pp. 600-656. 



Lithology, by A. A. Julien: Geol. of Mich., Vol. II, 1873, pp. 1-197. Appendix A. 



Geology of the Menominee iron region, by C. E. Wright: Geol. Survey of Wis., 1880, part 8, 

 pp. 690-717. 



