REVIEWS 167 



extending westward into Vermont. The field work is supplemented by 

 a quantitative chemical and mineralogical study of the schists and 

 granite of the region, leading the author to the conclusion that the 

 schists are of sedimentary origin. 



"A Contribution to the Geology of Essex County, Vermont," by 

 Rolf A. Schroeder: A study of the occurrence and possible commercial 

 exploitation of the Averill granite as a building stone. 



"Notes on the Areal and Structural Geology of a Portion of the 

 Western Flank of the Green Mountain Range," by Nelson C. Dale: 

 An investigation of the more mountainous portions of Middlebury and 

 Burlington Quadrangles, the geology including highly folded and faulted, 

 thoroughly metamorphosed, Cambrian and Pre-Cambrian sediments. 



"The Geology and Mineralogy of Braintree, Vermont," by Charles 

 H. Richardson and Charles K. Cabeen: Of interest is the discovery 

 of new graptolitic beds in the slates of Braintree and Rudolph proving 

 the southward extension of the Memphremagog slates in Braintree and 

 Rudolph to be early Ordovician. 



"A Detailed Study of the Trenton Beds of Grand Isle," by George 

 H. Perkens, and "A Report on the Fossils of the So-Called Trenton and 

 Utica Beds of Grand Isle, Vermont," by Rudolph Ruedemann. Pro- 

 fessor Perkins describes the distribution and character of the Trenton 

 beds of this locality and calls attention to the fact that the so-called 

 Utica beds present are but a portion of the Trenton. Dr. Ruedemann 

 supplements this paper with a discussion of the paleontology in which 

 faunal comparisons are made with the Trenton of New York and other 

 regions. The limestone he finds to correspond with the Glen Falls 

 division or basal Trenton, of New York, while the black shales are 

 referred to the Canajoharie shale of the same state, and in part also to 

 the Snake Hill division, or Schenectady beds. He comes to the conclu- 

 sion that the Ordovician is represented in Vermont by beds probably 

 no younger than the Trenton. 



"Progress in Talc Production," by Elbridge C. Jacobs: There is 

 an increased demand for talc due to substitution of the domestic material 

 for the foreign product, and increase in the number of uses to which it 

 is put. A complete list of known uses of talc is given, reprinted from a 

 United States Bureau of Mines Bulletin. 



"Studies in the Geology of Western Vermont," by Clarence E. 

 Gordon: A detailed description of the physiography, stratigraphy, and 

 structure of an extensive area in Western Vermont. A bibliography is 

 appended. 



