146 Scientific Intelligence. 



3. Geology of the Green Mountains in Massachusetts; by 

 Raphael Pumpelly, J. E. Wolff, and T. Nelson Dale (IT. S. 

 Geol. Survey Monograph, vol. xxiii, 1894), pp. i-xiv, 1-206, pis. 

 1-23. — This monograph is the result of thorough investigations 

 of the structure, petrography and minute texture of the rocks of 

 a most difficult metamorphosed region, which were begun in 

 1885, and although the grander features of the interpretation were 

 substantially reached in 1888, later studies have enabled the 

 authors to correct and confirm the interpretations as now pub- 

 lished. 



The monograph is composed of three separate parts ; the first, 

 by Raphael Pumpelly, defines the nature ol the problems involved, 

 and their importance and bearing in bridging over from the dis- 

 crete formations in the western undisturbed regions to the thor- 

 oughly metamorphosed schists of the more eastern areas of New 

 England. The chief difficulties lay in the correlation of the con- 

 tinuous series of metamorphosed schists of the Hoosac mountain 

 series with the series of conglomerates, limestones and schists of 

 the Graylock area. Regarding the lower members of the series, 

 Mr. Pumpelly interprets the "transitional coarse gneisses" to be 

 the result of a Cambrian transgression. He imagines the Cam- 

 brian transgression to have found an Archaean elevation, forming 

 the western border of an Archasan dry region, and that the rocks 

 of this dry area had become disintegrated the products varied 

 from kaolin and quartz to semi-kaolinized material, and the 

 detritus of sand and pebbles arising from this disintegrated 

 material was deposited with varying proportions of its constitu- 

 ents in a continuous sheet in progressive " transgression " over 

 the previously dry land. Thus quartzite in one place is inter- 

 preted as of the same horizon as the gneiss in another. The white 

 gneisses and conglomerates of Hoosac mountain are correlated 

 with the Cambrian quartzite, the albitic schists of Hoosac moun- 

 tain with both the limestone and schist of the valley. The 

 metamorphism of the Paleozoic rocks is interpreted as intimately 

 connected with the folding which the rocks of the whole region 

 have suffered ; but while structural differences are so explained, 

 differences in composition are explained by the exceptional char- 

 acter of the original sediments. 



The second part, by J. E. Wolff, " The Geology of Hoosac 

 Mountain and adjacent Territory," gives a petrographic descrip- 

 tion of the rocks, with beautiful photo-reproductions of the struc- 

 tures of the metamorphic conglomerates, the albitic schists, the 

 Stockbridge limestone and the amphibolites, together with a 

 detailed elaboration of the structural geology of the region. 

 Although this author concludes that the metamorphic rocks are 

 chiefly of detrital origin, he is not prepared to say that the 

 granitoid gneiss is an altered sediment. 



Mr. Dale's paper, Part III, " Mount Graylock ; its areal and 

 structural geology," is particularly interesting for its application 

 of a microscopic study of the structure of the foliation of the 



