Petrological Abstracts and Reviews 



Edited by ALBERT JOHANNSENi 



Clarke, F. W. " Analyses of Rocks and Minerals from the Labora- 

 tory of the U.S.G.S.," Bull. U.S. Geol. Survey No. 41Q. Pp. 315. 

 1910. 

 Bulletins 220 ("Mineral Analyses") and 22S ("Analyses of Rocks") 

 are combined in this edition and brought up to date. The conventional 

 form of stating analyses is retained and the same method of treatment is 

 followed. New Analyses: igneous rocks 56; sandstones, cherts, and 

 sinters 21; carbonate rocks 39; slates and shales 3 ; soils, etc., 21; minerals 

 93. With these additional analyses there is a reduction of 169 pages which 

 gives a large amount of valuable information in a small, compact bulletin. 



Charles J. Hares 



Dale, T. Nelson. "The Granites of Vermont," Bull. U.S. Geol. 

 Survey No. 404. Pp. 133, pis. 5. 1909. 



This work is a companion bulletin to those on the granites of Maine 

 (No. 313), and of Mass., N.H., and R.I. (No. 354). Its method of treat- 

 ment is both scientific and economic. 



Part I. Geographically the granitic areas extend in a northeasterly 

 direction between the central Green Mountain axis on the west and the 

 Connecticut River on the east for almost the entire length of the state. The 

 granites are of three types: (i) biotite granite, as that at Barre; (2) quartz 

 monzonite, as that at Bethel; and (3) hornblende- augite granite — the 

 "olive-green syenite" of Daly — as that from Mount Ascutney. The age 

 of the Ascutney granite is placed as post-Carboniferous or pre-Cretaceous, 

 that on the west side of Green Mountain as late Devonian or Carbonif- 

 erous, and the traversing dikes as possibly Triassic. The author's con- 

 clusions are based largely on the works of Richardson and Daly. 



Special points emphasized are: double sheeted structure, that is, a 

 structure with horizontal jointing; compressive strain, which is illustrated 

 by the elliptical shape assumed by the drill holes; schist inclusions; con- 



I Abstracts may be sent to Albert Johannsen, Walker Museum, The University of 

 Chicago, Chicago, 111. 



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