REVIEWS 547 



Both lithologically and paleontologically the Pottsville formation 

 constitutes a division of the Carboniferous coordinate with the Lower 

 Coal-measures, Alleghany series, etc. As such it forms the lower 

 member of what may in a broad sense, be termed the Mesocarbonifer- 

 ous in the Appalachian province. 



The lowest beds in the thickest sections, which appear to be con- 

 tinuous by transition with the deposition of the Maunch Chunk red 

 shales, are perhaps to be regarded as coarse, coast-detrital redeposi- 

 tions, contemporaneous with the uppermost beds of the red shale or 

 marine Lower Carboniferous sediments of other regions. 



The flora of the Pottsville formation is so far identical, in both its 

 generic and its specific composition, with that from the supposed 

 Middle Devonian beds at St. John, as to leave no room for a great 

 difference in the age of the latter. 



Charles R. Keyes. 



lozva Geological Survey ; Samuel Calvin, State Geologist ; 

 A. G. Leonard, Assistant State Geologist ; Annual Report for 

 1900 (Vol. XI, 519 pages, 12 plates, 43 figures, 9 maps. Des 

 Moines, 1901). 



In scope and style this report follows closely the previous volumes 

 of the series. It includes the usual administrative reports, the statis- 

 tical reports of the mineral production, and detailed reports on 

 Louisa, Marion, Pottawattamie, Cedar, Page, and Clay and O'Brien 

 counties, the last two being treated together. These reports are 

 written by J. A. Udden, B. L. Miller, J. A. Udden, W. H. Norton, 

 Samuel Calvin, and T. H. Macbride respectively. They contain a 

 careful review in each case of the local geology and serve to put on 

 record facts and observations which may be used in later discussion of 

 the theoretical problems involved. Following the usage of the survey, 

 these discussions are taken up as fast as the development of the gen- 

 eral survey allows them to be intelligently discussed. In the case of 

 Louisa county, for example, the problems of the drift of that region 

 have already been discussed in their theoretical phases in Mr. Udden's 

 report on Muscatine county, Mr. Norton's report on Scott county, and 

 Mr. Leverett's well-known monograph.' In the Louisa report Mr. 

 Udden gives many interesting and valuable details confirmatory of the 



'U. S. Geol. Surv., Mon. XXXVIIL The Illinois Glacial Lobe. 



