AMERICAN GEOLOGY DECADE OF 1860-1869. 539 



this salt must have been soon decomposed by the abundant acid car- 

 bonate of lime, he could not suppose it to have been effectual in the 

 final concentration of the large deposits, and he thought it more prob- 

 able that this last was accomplished by the more permanent solution 

 of carbonate and silicate of copper. 



Pumpelh T was assisted by A. R. Marvine, L. P. Emerson, and S. B. 

 Ladd. 



Rominger's report on the Paleozoic rocks of the Upper Peninsula 



formed part 3 of the third volume of the Survey reports (1873). His 



second appeared in 1876, forming one of the four large octavo volumes 



of the Survey, comprising altogether some 386 pages, 



C. Rominger's Work ... „„ , „ , ., , , 1 i • i 



in Michigan, 1873- with oo plates of fossils, and a colored geological map 

 of the area surveyed. The geological portion contains 

 a record of the characteristic rocks, their geographical distribution, 

 and the fossils they contain. It is to be noted that Rominger showed 

 a disposition to disagree in many of his conclusions with Winchell, 

 Brooks, and others who had preceded him. 



The presence of large bowlders in the midst or on top of well-stratified 

 drift layers he conceived to be due to the transportation of the material 

 by means of swimming icebergs during periods of flood. In this he 

 agreed, substantially, with Dawson, of the Canadian Survey. The 

 dolomites of the Ida quarries, which Winchell identified as belonging 

 with the Onondaga salt group (Upper Silurian), he considered as Upper 

 Helderberg (Middle Devonian), and he stated that the mapping b}^ 

 Winchell of Upper Helderberg rocks throughout a great portion of 

 Cass, Van Buren, and all over Berrien County, was an error. He also 

 differed with Winchell regarding the stratigraphic position of the 

 Hamilton rocks of Big Traverse Bay. Winchell's Huron shales he 

 considered from paleontological evidence, to be identical with the 

 Cuyahoga shales of the Ohio geologists, and, therefore, belonging to 

 the lower part of the Carboniferous rather than the Upper Devonian. 

 He also accused Winchell of a peculiar stratigraphic blunder in pre- 

 paring a section west of Flat Rock: 



Unfortunately this section is laid across a synclinal undulation of the formation, 

 and begins at one end with the same rock beds (Marshall sandstone), which on the 

 other end are found very near the base. Under the impression that he was all the 

 while descending, he stands again on the horizon from which he started. 



The salt brines of the State, according to Rominger, are derived 

 from rocks of the Waverly group, and not from those of a higher 

 horizon, which Winchell had designated as the Michigan salt group. 



Rominger also made reports on soils, building stones, and slate 

 quarries, and on the Ontonagon silver mining district. What is per- 

 haps the most valuable part of the report is that relating to the fossil 

 corals- which was. for its time, unsurpassed. 



