PETROLOGY IN AMERICA. 481 



to be metamorphosed sediments, are all recognised as true 

 igneous rocks, either contemporaneous or intrusive ; and 

 the serpentines, instead of arising from the metamorphism 

 of various sedimentary rocks, are found here, as in other 

 countries, to be decomposed basic and ultrabasic eruptives. 

 Of the formidable series of supposed metamorphic rocks 

 described in Monograph XIII. there remain only the 

 glaucophane-bearing and other crystalline schists, and these 

 seem to be in all cases contact-zones bordering intrusions of 

 basic rocks (36). 



BIBLIOGRAPHY. 



(i) Adams, Frank D. Ueber das Norian oder Ober-Laurentian 

 von Canada. Neu. Jahrb. fur Mm., Beil. Bd. viii., pp. 

 419-498, 1893. 



{2) Lawson, Andrew, C. The Anorthosytes of the Minnesota 

 Shore of Lake Superior. Bull. No. 8 of Geol. and Nat. Hist. 

 Surv. Minn., pp. 1-23, 1893. 



{3) BAYLEY, W. S. The Basic Massive Rocks of the Lake 

 Superior Region, four, of Geol., vol. i, pp. 433-456, 587- 

 596, 688-716; vol. ii., pp. 814-825; vol. iii., pp. 1-20, 



I893-5- 

 {4) KEMP, J. F. Gabbros of the Western Shore of Lake 



Champlain. Bull. Geol. Soc. Atner., vol. v., pp. 213-224, 



1894. 



(5) Kemp, James Furman. The Geology of Moriah and West- 



port Townships, Essex County, N.Y. Bull. N. Y. State 

 Mus., vol. iii., No. 14, pp. 325-355. i§95- 



(6) Smyth, C. H., Jr. Crystalline Limestones and Associated 



Rocks of the North-western Adirondack Region. Bull. Geol. 

 Soc. Amer., vol. vi., pp. 263-284, 1895. 



(7) BAYLEY, W. S. A Fibrous Intergrowth of Augite and 



Plagioclase resembling a Reaction Rim in a Minnesota 

 Gabbro. Amer. fourn. Sci. (3), vol. xliii., pp. 515-520, 

 1892. 



(8) Kemp, J. F. The Nickel Mine at Lancaster Gap, Penn- 



sylvania and the Pyrrhotite Deposits at Anthony's Nose 

 on the Hudson. Trans. Amer. Inst. Mining Engin., 14 pp. 

 1894. 



(9) Kemp, J. F. Crystalline Limestones, Ophicalcites and 



Associated Schists of the Eastern Adirondacks. Bull. Geol. 

 Soc. Amer., vol. vi., pp. 241-262, 1895. 



34 



