Reviews. 



VAN HISE'S "PRINCIPLES OF PRE-CAMBRIAN GEOLOGY." 



For some years investigators and teachers of dynamic geology 

 have needed a revision of the theories of Dana, Fisher, Reade, Dut- 

 ton, Kelvin, and others, with reference to rock deformation. The 

 publications of Van Hise are a contribution to such a revision, and 

 other articles in preparation by him may probably summarize existing 

 knowledge and current theory in a form, which will be a material 

 advance. 



By training, experience, and bent of mind, Van Hise is fitted for 

 the task. As assistant and successor to Irving in the geologic investi- 

 gation of the Lake Superior iron region, he has solved the most diffi- 

 cult problems of the older rocks. In microscopic petrography of the 

 crystalline schists and allied formations he is a leading authority. In 

 obscure stratigraphy and complex structural relations he has had much 

 experience. His base of observation has been broadened to include 

 all important districts from the Pacific to the Atlantic, and the classic 

 localities of Europe. 



The Principles of Pre- Cambrian Geology is a work intended " (i) to 

 give a partial discussion of principles applicable to geological work 

 among the pre-Cambrian rocks of North America, and (2) to give an 

 historical account of the North American pre-Cambrian, and to point 

 out the principles illustrated in the various regions." 



In Part I the author discusses (1) movements of rock materials 

 under deformation, (2) analysis of folds, (3) cleavage and fissility, (4) 

 joints, (5) faults, (6) autoclastic rocks, (7) metamorphism of the sedi- 

 mentary rocks, (8) metamorphism of the igneous rocks, (9) phenomena 

 of stratigraphy. 



Part II describes the facts of historical geology in general for the 

 Archaean and Algonkian periods, and in particular for ten districts of 

 the United States and Canada in which rocks of these ages occur. 

 There is an appendix on " Flow and Fracture of Rocks as Related to 



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