168 BULLETIN 10f>, UNITED STATES NATIONAL MUSEUM. 



Woodville sandstone of later geologists at the top of the coal meas- 

 ures of the State, but at some points the rock is not within the 

 measures, and not unlikely some of the southwestern exposures are 

 of the Paniia sandstone or conglomerate. The various exposures of 

 coal in Ingham County are next enumerated. 



The report of assistant geologist, Bela Hubbard, consisting of 38 

 pages, relates to Wayne and Monroe Counties. He treats of Wayne 

 County under the following heads: Topographical features; soil and 

 agricultural character; bowlders; marshes and wet prairies; en- 

 croachments of the river and lakes; clay; limerock; marl.; peat; 

 bog iron ; chalj'beate springs ; sulphur springs ; brine springs ; water 

 wells and springs; roads. 'Monroe County is treated under nearly 

 the same heads. The limerock is discussed no further than to enum- 

 erate its various outcrops and describe its character. The outcrops 

 in Monroe County are recognized as lying in several distinct ranges, 

 extending in a northeast and southwest direction. The dip is slated 

 at about 5° northwest or northwest hy north. He notices a bed of 

 sandstone included in the formation and describes it as sufficiently 

 pure for glass making. He calls attention to a number of " sink 

 holes," one of which covers nearly 100 acres. The water which ac- 

 cumulates in them disappears " through cavernous apertures in the 

 limestone below." The limestone is designated by Mr. Hubbard 

 " the mountain limerock." 



THIRD YEAR OF THE SURVEY, 1839. 



The report of the State geologist bears date of February 3, 1840, 

 and, with the accompanying documents, covers 124 pages, of which 

 33 pages relate to Doctor Houghton's personal observations and 

 studies. A portion of the season had been devoted " to an examina- 

 tion of the southern slope of the part of the Upper Peninsula extend- 

 ing from the Sault de Ste. Marie to the mouth of the Menominee of 

 Green Bay, a district of country which, with very few exceptions, 

 is a perfect wilderness." After a sketch of the physiographic fea- 

 tures of this district, in which he points out the prospective impor- 

 tance of the lake fisheries, he approaches its general geology. The 

 rocks, he says, are but little varied, and " consist of a series of well- 

 defined limestones and shales that occupy the complete range from 

 Drummond's Island of Lake Huron to Menominee River of Green 

 Bay. As we proceed toward the declivity of the Upper Peninsula, 

 the red sandstone of Lake Superior makes its appearance, underlying 

 the groups of limestones and shales before mentioned." All these 

 rocks are bounded on the east by a range of hills composed of pri- 

 mary rocks, chiefly of quart?;, hornblende, and greenstone. The 



