342 THE GEOLOGIC ATLAS OF THE UNITED STATES 



by a summary account of the geography, including climate and 

 vegetation, agriculture, etc. Next follows an account of the gen- 

 eral geology, including a history of physical changes, set forth 

 verbalty and graphically. In this division of the work the char- 

 acteristics of the formations are described, the sources of materials 

 are -considered, the subsequent alterations recorded in texture 

 and structure are investigated, and the great orogenic and epeiro- 

 genic movements that produced the majestic Rocky mountains 

 and (especially) the broad plains at their base are interpreted — 

 i. e., the phenomena are treated both locally and comparatively, 

 and in remarkably luminous and attractive fashion. The for- 

 mations range from recent alluvium through earlier Pleistocene, 

 Neocene, Cretaceous, Juratrian, Carboniferous, and Silurian to 

 the Archean nucleus exposed in the ranges ; and there were sev- 

 eral periods of deformation, the movements of which have been 

 analyzed and clearly set forth. In describing the formations 

 and discussing the deformations full recognition is given to the 

 principles of geomorphy and to homogenic correlation, and the 

 histor}'' of the tract is thereby made clear and definite. There 

 is a final chapter on economic geolog}' in which the resources, 

 including phreatic water, are fully described. 



This synopsis merely indicates the scope of a notable publica- 

 tion ; it does not and cannot give any adequate idea of the high 

 scientific and educational value of a great work which can be 

 properly appreciated only after examination. It is not too much 

 to say that this atlas folio by itself would, in the hands of a com- 

 petent teacher, serve as a complete introduction to geology, by 

 means of which any pupil might gain an elementary knowledge 

 of the science; or that in the hands of a competent teacher (or, 

 indeed, of an intelligent student without a teacher) within the 

 tract described the work would be more serviceable than any 

 manual or text-book of geology ever written. The publication 

 of these atlas-folios representing particular tracts in all parts of 

 the country is bound to revolutionize geologic teaching quickly, 

 completely, and permanently. W J M. 



At the annual meeting of the Royal Geographical Societ}^, 

 held recently in London, the Founders' Medal of the Society 

 was conferred on Dr Sven Hedin for his explorations in Central 

 Asia, and the Patrons' Medal on Lieut. Robert E. Peary, U. S. N., 

 for his work in Greenland. 



