48 THE MAECiUETTE IKON-BE AKING DISTRICT. 



WiNCUELL, Alexander. Report on llie progress of the State geological 

 survey of Micbigan. Lansing, 1S71. (H pages. 



The second State geological survey of Michigan was established in 

 May, 1869, with Alexander Winchell as State geologist. Under its opera- 

 tion several valnaljle reports were made, and a new era in the history of 

 geological work in the Marqnette district was ushered in — an era of activity 

 snch as had not been known since the days of Bnrt, Hnbbard, Jackson, 

 and Foster and Whitney. 



In his report of progress the State geologist mentions the condition of 

 the work intrusted to his care, and outlines the contents of the proposed 

 volumes intended to be issued by the survey. With relation to the 

 Marquette district, he states that — 



the rich masses of magnetic and hematitic ores of iron are fonnd not to be those 

 erujited outbursts which the older geologists were inclined to regard them. They 

 are simply constituents of the system of sedimentary deposits which make up the 

 Huronian system of Michigan. The diorites of the region appear to be equally of 

 sedimentary origin, and are found strictly interstratifled with chloritic, silicious, 

 taleose, argillaceous, micaceous, and hematitic schists. * * * (Pp. 26-27.) 



A few other references are made to tlie geology of the Marquette district, 

 and a scheme of superposition for the rocks found there is given; but the 

 same subjects are treated more fully in Brooks's report. 



Brooks, T. B. Iron-bearing rocks (economic). Geol. Surv. of Michigan, Vol. 

 I, 1869-1873, New York, 1873, Part I. 319 pages. With maps. 



In this i'e})ort the author first gives a history of the development of 

 the iron-ore industry on the Upper Peninsula, and then briefly character- 

 izes the difi^erent systems of rocks occiu-ring therein and outlines their 

 distriliution. He recognizes the Laurentian, Huronian, Copper-bearing, 

 and Lower Silurian series, and after a few remarks on the topography of 

 the region underlain by the rocks of each series he proceeds to the detailed 

 desci-iption of the IMarc^uette area. It is with this j)ortion of his paper that 

 we are most concerned. 



