GEOLOGICAL EXPLORATIONS AND LITERaTLTRE— 1873. 59 



Wright, Charles K. ^Microscopic tleteriniuatioiis and descii|iti(iiisot" 78 speci- 

 mens of Huroniau rocks and ores. Geol. Surv. of Michigan, 1SG9-1S73, Api)eudix C, 

 Yol. II, New York, 1873, pages 213-231. 



Ill the tliird appendix Wright elassities for the first time the rocks of 

 the Marquette area in accordance witli their microscdpical features. 1 )iorites, 

 diorite - schists, ohh )rite - schists, hornblende - scliists, anthophvlHte - schists, 

 quartzites, argillites, and various specimens of ores -were sul)mitted to tlie 

 author, who describes them briefly, Init -with sufKcient fullness to make their 

 recognition ])ossible. Wright surmises tliat diabase mav exist among the 

 greenstones of the region. 



Houghton, Douglass. Remarks on rocks between Chocolate River and 

 Granite Point, embracing Marcxuette Harbor. From unpublished MS8. Geol. Surv. 

 of Michigan, 1800-1873, Appendix E, Yol. II, New York, 1873, pages 23!»-24(J. 



These notes, which comprise the iiftli appendix to Hmoks's report, 

 possess only a historical value because of the long delay in their publication. 

 It is unnecessary to refer to them further than to state that the author dis- 

 covered and figurt'd the unconformity l)etweeu the Lake Superior sandstone 

 and the quartzite near the mouth of the Carp IJiver. 



Brooks, T. B. The lamination, plication, and faulting of banded ore and 

 jasper (mixed ore), with illustinitious (figs. 10 to 20). Geol. Surv. of Michigan, 

 1869-1873, Appendix K, Yol. II, pages 283-202. 



The final appendix is one added ]>y Brooks liimself It comprises 

 eleven figures of banded jasper and ore, with their exjjlanation. Its object 

 is to illustrate the Avay in which the original parallel lamination of the ore 

 and jasper may be entirely obliterated, and may be replaced by a mechanical 

 brecciated structure. The figures are yery interesting and suggestive. 



ROMINGER, C. PaliBOZoic rocks. Geol. Surv. of Michigan, 1S(;0-1S73, Yol. I, 

 Part III, New York, 1873, 101 pages. 



In the same volume of tlie jMichigan survey in which Brooks's report 

 occurs is one by Rominger on the Paleozoic I'ocks of the Upi)er Peninsula. 

 The only portions of this report in which we are now interested are those 

 relating to the unconformity between the Huroniau and the Potsdam beds 

 near Marquette, and the description of the Presque I.sle rocks. 



