380 Reviews — The Arctic Basalt Plateau. 



Dr. Smith Woodward, and some foraminifera are included in this 

 paper as an appendix by Heron-Allen and Earland. 



Mr. Newton, while formerly laying stress on the similarity of the 

 fauna to the Claiborne, Mokattam, and European Middle-Eocene, 

 has now, after further study, come to regard this as an Upper 

 Lutetian stage, recognizing at the same time the Bartonian facies 

 of the material. The Mollusca are extremely well preserved, and 

 have been reproduced from the excellent photographs of Mr. P. 

 Dollman. Mr. A. E. Kitson and Dr. J. D. Falconer must be con- 

 gratulated on securing the publication of so interesting a collection, 

 which forms a valuable addition to our knowledge of the geology 

 of this part of West Africa. 



On the Eastern Part of the Arctic „ Basalt Plateau. By 

 H. G. Backlund. Meddelanden fran Abo Akademis Geologisk- 

 Mineralogiska Institut, No. 1. pp. 53, with 2 text-figures. 

 Abo, 1920. 



/^UR knowledge of the great basalt plateaus of Siberia is very 

 ^ slight in comparison with the great amount of detail available 

 as to the western and extreme northern parts of the Arctic Province. 

 The paper now under review is a most tantalizing production, since 

 the author states that he had in his possession material from regions 

 covering the whole of the eastern area, hinting darkly at a mysterious 

 accident which deprived him of almost all his specimens and notes. 

 After this catastrophe he decided to publish a detailed account of the 

 small amount that remained. Full descriptions are given of three 

 specimens, one from Bennett Island in the extreme north of the 

 New Siberian Islands, and one from Wilkitski Island, to the east of 

 the same group ; the third specimen examined in detail came from 

 the Adzra river, in the Petchora region, west of the Urals. The first- 

 named proves to be an olivine-trachydolerite, the second a basaltoid 

 nephelmite; and the third a basalt very like a type described from 

 Spitsbergen, and of the normal Brito-Arctic facies. From these 

 results, and from the author's general knowledge of the eastern 

 plateau, it is concluded that the rock-types found are very similar 

 to those of the western and northern areas from Spitsbergen to 

 Britain, namely, for the most part normal basalts and olivine-basalts, 

 with an occasional local lapse into alkaline types. 



The physiographic relations of the Siberian basalts are peculiar ; 

 the lava-flows only occur in deeply eroded valleys, which they partly 

 fill. Apparently the fissures never opened as high as the general 

 plateau surface, which consists of sedimentary rocks. The extrusion 

 of the lavas is correlated with isostatic continental uplift on a large 

 scale. Unfortunately, in the concluding and most interesting sections 

 of the paper, the author's English becomes somewhat obscure, and 

 some of his points are difficult to follow ; he seems to consider, 

 however, that in addition to isostatic adjustment some form of 



