REVIEWS. 747 



ate in Africa, South Asia and Australia is characterized by Mesozoic 

 types. This change is believed by many to have been brought about 

 by the cold climate which was the determining cause of the conglom- 

 erate beds. Blanford and Waagen go further and connect the decline 

 of the marine Paleozoic types with the cold climate of the end of the 

 Paleozoic. 



In the discussion of the Mesozoic and Neozoic there is scarcely any 

 reference to American geology. In connection with the discussion of 

 Pleistocene geology, two glacial epochs are recognized. The author 

 inclines to the eolian hypothesis for the origin of loess. 



Both the physical and paleontological phases of the subjects dis- 

 cussed in the volume are illustrated by numerous figures, the former 

 rather less fully than the latter. A series of maps, showing the distri- 

 bution and relations of the systems described, would have enhanced 

 the value of the volume which is still great without them. 



Rollin D. Salisbury. 



Iowa Geological Survey. Vol.1. First Annual Report, 1892. Samuel 

 Calvin, State Geologist, Des Moines, 1893. 8vo, 472 pp., 10 

 plates and 26 figures. 



In addition to brief administrative reports, the first report of 

 Iowa's third survey contains papers by S. Calvin, C. R. Keyes, Assistant 

 State Geologist, S. W. Beyer, H. F. Bain and G. L. Houser. 



The introductory paper by Mr. Keyes, on the Geological Formations 

 of Iowa, is a summary of present knowledge of the various formations 

 occurring within the limits of the state. The writer has availed him- 

 self of the various studies made of these rocks in recent years, and the 

 result is shown in an improved classification over that of preceding 

 surveys. While all the formations have come under careful study, the 

 most notable progress is shown to have been made in the classification 

 of the Devonian, the Carboniferous and the Cretaceous. 



Investigations in northwestern Iowa have brought to light the 

 presence of undoubted eruptive rocks at no great depth below the 

 surface. In Mr. Beyer's paper are given the details relating to the 

 discovery of typical quartz-prophyry, interbedded with sandstone 

 and gravel, in a deep well at Hull, Iowa. The discovery by Culver 

 and Hobbs of eruptive rock within the Sioux quartzite in southeastern 



