GEOLOGICAL AND NATURAL HISTORY SURVEYS. 171 



of nine counties. As if this were not sufficient for a season's work, 

 he says, in beginning his report: 



In addition to the geological exaniimitlons, specimens liave been collecfed 

 tllustratlng the geology, minerr.logy, and soils of tbe counties examined, and 

 * * * field notes for tbe constructioa of accurate topographical maps of 

 nearly every township examined during the past season have been returned to 

 that office [the topographer's]. 



The counties examined were Jackson, Calhoun, Kalamazoo, Eaton, 

 Ionia, Kent, Ottawa, Van Buren, and Allegan. 



In treating these Mr. Douglass gives full details of marls, which 

 are said to occur in nearly every town. He makes brief mention of 

 peat, and devotes a page to clays and sands. He notes the abundance 

 of bowlders of primary rocks; details several occurrences of bog 

 iron ore; mentions kidney ore in Calhoun County; emphasizes the 

 importance of the gypsum of Kent County. Coming to the rocks 

 of the central district of the Peninsula, he recogTiizes two divisions — 

 " the rocks which overlie or associated with the coal, and those which 

 lie below the lowest coal beds." The latter division is remitted to 

 Mr. Hubbard to discuss, while Mr. Douglass takes the coal series. 

 This series he finds made up as follows: 



1. Upper coal strata, consisting of layers of coal, shale, and sand 

 stone. 



2. Limestone, found in limited and apparently irregular beds. 



3. Sandstone, light graj?^ and red. 



4. Lower coal strata, embracing as above, alternating layers of 

 coal, shale, and sandstone. 



As to the lower coal strata, Mr. Douglass's demonstrations are 

 not quite satisfactory. He regards the sandstones of Calh'oun County 

 as belonging here and believes them to be embraced in the coal meas- 

 ures, because fragments of coal occur in the diluvium at Albion, 

 Penfield, and Battle Creek. The " light gray sandstone " is said to 

 occur near Jackson, and to be quarried in Calhoun, Eaton, and other 

 counties well known to be underlaid by coal. This is the material 

 of the penitentiar}^ in Jackson. The "upper limerock" is cited 

 from Spring Arbor, Parma, Bellevue, and Grand Rapids — all 

 localities now known to be underlaid by the Lower Carboniferous 

 limestone. In supplying the local details of the upper coal group, 

 Mr. Douglass is not conscious that he describes precisely the same 

 coal-bearing strata as he had previously described in Jackson County 

 us constituting the lower coal series; and the limestone described, 

 instead of intervening between the lower and upper coal groups is 

 imclerneath all the coal-bearing strata. Hence he is led to remark: 



This gives a greater thickness to the coal-basin than had been before snp- 

 posod. and also proves, what bad been previously suggested, that the Grand and 



