RECENT ADVANCES IN SCIENCE 571 



members. There is a well-marked similarity in characters 

 and sequences between the two magmas, although the simi- 

 larity does not extend to details. 



Mr. J. F. N. Green has made a comprehensive study of the 

 vulcanicity of the Lake District (Proc. Geol. Assoc.,' 1919, 30, 

 153-82), in which he comes to the conclusion that the special 

 features of the lavas and tuffs indicate that they were accumu- 

 lated on the sea floor probably at a considerable depth. He 

 also emphasises the importance of the evanescent gaseous 

 and liquid constituents of magmas in producing mineralogical 

 and structural modifications of the resulting rocks. 



Mr. J. Morrison presents a notable contribution to Lake 

 District petrography in his paper on the Shap minor intrusions 

 (Q.J.G.S., 1919, 74, pt. 2, 116-44). He appeals to a rather 

 complicated series of processes, including gravitative differ- 

 entiation and syntaxis, as important factors in producing the 

 observed diversity of rock types. 



An interesting study of the basal phases of the great Duluth 

 gabbro mass and its contact effects near Gabamichigami Lake, 

 Minnesota, has been made by the late Dr. M. L. Nebel (Econ. 

 Geol., 191 9, 14, 367-402). He believed that the gabbro had 

 contributed material, especially metallic sulphides like those 

 of Sudbury, to the metamorphosed rocks. 



According to H. C. Cooke (Geol. Surv. Canada, Mus. Bull., 

 No. 30, 191 9, p. 48), a large gabbro complex at East Sooke 

 (Vancouver Island) consists mainly of olivine-gabbro, with sub- 

 ordinate quantities of augite-gabbro, anorthosite, and granite, 

 disposed in such a way as to indicate gravitative differentiation 

 as the geological process concerned in their mutual arrange- 

 ment. After consolidation the complex was intruded by two 

 series of satellitic dykes, gabbro-aplites and granite-aplites, 

 in the order given. Hornblendisation by hot solutions took 

 place still later along broad shear zones. 



The plutonic mass of Cape Willoughby (South Australia) is 

 an adamellite, with minor intrusions of microcline-aplite and 

 albitite (Tilley, Trans. Roy. Soc. South Australia, 1919, 43, 316- 

 41). In form it is chonolithic, and is arranged, along with 

 other granitic intrusions, parallel to the strike direction of the 

 older Palaeozoic folding. According to the same author, cer- 

 tain quartz-tourmaline nodules in this granite owe their origin 

 primarily to pneumatolytic processes (ibid., pp. 156-65). The 

 term pneumatolith is proposed for nodules resulting from these 

 processes. 



The following are further references to recent important work : 



Davis, W. M., The Framework of the Earth, Amer. Journ. Sci., 1919, 48, 

 225-41. 



