178 Some Recent American Petrological Literature. 



"V. — Some Recent American Petkological Liteeatube. 



(Continued from p. 128.) 



" Structure of the Anorthosite Body in the Adiron clacks," by H. P. 

 Cushing. Journ. Geol., vol. xxv, pp. 501-8, 1917. 

 A criticism of Dr. Boweu's conclusions as to the field relations of 

 the different rock-types of the area. 



''Adirondack Intrusives," by ~N. L. Bowen. Ibid., pp. 509-12, and 

 H. P. Cushing, ibid., pp. 512-14. 

 A continuation of tbe discussion on the two preceding papers. 



" The Relation of the Titaniferous Magnetite Ores of Glamorgan 



Township, Haliburton County, Ontario, to the Associated 



Scapolitic Gabhros," by W. G. Foye. Econ. Geol., vol. xi, 



pp. 662-80, 1916. 



It is concluded that gases given off by the acid and intermediate 



magmas collected beneath the gabbro, oxidizing its iron to titaniferous 



magnetite and depositing this below the laccolith ; the chlorine and 



other gases thus set free scapolitized andrecrystallizedthe overlying 



gabbro. 



"The Relation of the Titaniferous Magnetites of North-Eastern 



Minnesota to the Duluth Gabbro," by T. M. Broderick. Econ. 



Geol., vol. xii, pp. 663-96, 1917. 



The gabbro has developed magnetite-bearing rocks along its 



contact with the Gunflint iron formation, including coarse-textured 



fayalite-pyroxene-magnetite rocks, hitherto mistaken for marginal 



facies of the gabbro. Several types of magnetic ores within the 



gabbro are partly magmatic segregations and partly inclusions of the 



Gunflint formation. 



" The Geology of Pigeon Point, Minnesota," by R. A. Daly. Amer. 

 Journ. Sci., vol. xliii, pp. 423-48/ 1917. 



A re-examination of the occurrence of micropegmatite (red rock) 

 in a basic intrusion. The intrusion is considered to be a sill, not 

 a dyke, as supposed by Bayley, and the variation in composition is 

 due to differentiation, mainly by gas-action, after stoping and 

 assimilation of Animikie quartzite. 



"Petrography of the Pacific Islands," by R. A. Daly. Bull. 

 Geol. Soc. Amer., vol. xxvii, p. 325, 1916. 

 The available data lead to the conclusion that the primary Pacific 

 magma is basaltic and that andesites and ultrabasic lavas have been 

 differentiated from this : certain alkaline types may be limestone 

 syntectics. 



" A Contribution to the Petrography of the South Sea Islands," by 

 J. P. Iddings and E. W. Morlev. Proc. Nat. Acad. Sci., vol. iv,. 

 pp. 110-17, 1918. 

 Analyses are given of rocks from Tahiti and other islands of 

 the Georgian and Society groups, many of which are profoundly- 

 eroded volcanoes, consisting mainly of basalts rich in augite and 



