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origin, as well as layers of coarse debris derived from cliffs, are fully 

 described, but no insh eared layers of mingled glaciated material ranging 

 from rock-flour to great striated bowlders are described. From the 

 causal point of view, this is a matter of the utmost importance, for this 

 kind of work is glacier work par excellence. But this review has already 

 grown so long that, most interesting as this is, it cannot be discussed here. 

 The book closes with "A Review of the Causes of Glacierisation " 

 (C. S. W.) (pp. 463-70). As the climax of a discussion of glacierization 

 of the colossal Antarctic type, this dwells too long on causes of climatic 

 variation whose known cycles are so short as to need to be multiplied 

 thousands or ten thousands of times to fit the glacial types, and not 

 long enough on the necessity of selecting causes whose cycles are of the 

 same order as those of the great glacial epochs themselves. Objections 

 to such putative causes, of course, presented themselves. From these 

 the discussion leads up (or down) to the suggestion that the theory of 

 Wegener, if tenable, might solve some of these difficulties. The reader 

 may perhaps sympathize with the reviewer in wishing he had closed the 

 book before he reached this anticlimax. But, without disguising the 

 fact that the report limps badly at times on one of its legs, it is neverthe- 

 less a contribution to glaciology of a very high order of value. 



T. C. C. 



Geology of the Tertiary and Quaternary Periods in the Northwest Part 

 of Peru. By T. O. Bosworth. London: Macmillan and Co., 

 Ltd., 1922. Pp. xxiiH-434, pi. 26, folders 11, fi.g. 150. 



This volume constitutes a very notable contribution to the geology 

 of South America. It is a departure from the reconnaissance reports 

 of large areas which constitute so large a part of the pioneer geologic 

 literature on South America, inasmuch as it reports in considerable detail 

 and in thoughtful and painstaking fashion careful geological observations 

 within a comparatively restricted area. 



The area described is a strip of arid territory twelve to fifteen miles 

 wide, lying between the westernmost range of the Andes and the Pacific 

 Ocean, a short distance south of the Ecuador boundary. The Amotape 

 Mountains to the east, 3,000 to 5,000 feet high, consist of Cretaceous and 

 Paleozoic rocks. From them a great "breccia deposit," or peidmont 

 alluvial plain, slopes westward onto a series of three pebble-covered 

 raised sea beaches, called Tablazos, which constitute plateaus stepped 

 up from sea-level to an elevation of 1,100 feet in the highest. Tertiary 



