PETROLOGICAL ABSTRACTS AND REVIEWS 495 



peridotites and pyroxenites are rarely amphibolites and olivine-gabbros, 

 more commonly eucrites and anorthosites. The silicic rocks described 

 are felsites, granodiorites, and various granites. Malchites, granite- 

 porphyries and quartz-porphyries, and minettes, vogesites, and camp- 

 tonites occur as dikes. 



Twenty-two analyses are given of rocks of this region, unfortu- 

 nately showing a number of typographical errors and errors in proof- 

 reading owing to the absence of the author from the state during the 

 passage of the paper through the press. 



The fourth paper deals with the dolerites, spilites, and keratophyres 

 of the Nundle District. In this the statement is made that the feldspar 

 of the keratophyre is pure albite and not acid oligoclase, as stated in the 

 earlier paper. The spilites, dolerites, and keratophyres all appear to be 

 intrusives in the sediments. Certain of the spilites, in the opinion of 

 the author, were intruded into soft mud, for they show a pillow structure. 

 Most of the rocks are rich in primary albite. 



The fifth paper is on the geology of the Tamworth District. A series 

 of radiolarian claystones was deposited at shallow depths on a steadily 

 sinking sea-floor in Devonian times. There were two periods of volcanic 

 activity, and masses of tuffs and agglomerates accumulated in the sea, 

 and spilites, dolerites, and keratophyres were intruded. The total thick- 

 ness of the series is unknown, but apparently about 12,000 feet are 

 Middle and Upper Devonian. Faulting and folding took place in the 

 Carboniferous period, followed by peridotitic intrusions, and later by 

 intrusions of granite. A final eruption of basalt occurred in the Ter- 

 tiary period. 



Berkey, Charles P. "Petrographic Range of Road-Building 

 Materials," School of Mines Quart., XXXV (19 13), No. 1, 

 pp. 6. 



Blanchard, Ralph C. The Geology of the Western Buckskin 

 Mountains. Dissertation. Columbia Univ., 1913. Pp. 80, 

 numerous figs. 



Boeke, H. E. "Bemerkung iiber die Theorie von J. Johnston 

 bezuglich des Verhaltens fester Stoffe unter ungleichformigem 

 Druck," Centralbl. f. Min., Geol., u. Pal., 1913, 321-24. 



