320 PETROLOGICAL ABSTRACTS AND REVIEWS 



Collins, W. H. "The Age of the Killarney Granite," Canadian 

 Geol. Surv., Museum Bull. 22 (1916). Pp. 12, pi. i, map i. 

 The Huronian formations along the coast of Lake Huron have been 

 greatly folded and faulted, and intruded by granite batholiths. Both 

 disturbance and granite invasion were completed long before Ordovician 

 time. 



Colony, R. J. " Petrographic Study of Portland Cement," School 

 of Mines Quart., Vol. XXXVI (19 14), pp. 1-2 1. Figs. 14, 

 bibliog. 14 items. 



Gives petrographic criteria by which the fitness of cement and 

 concrete may be judged. 



Daly, Reginald A. "Petrography of the Pacific Islands," Bull. 



Geol. Soc. Amer., Vol. XXVII (1916), pp. 325-44. BibHog. 



58 items. 

 Concludes that underneath the Pacific Ocean the only primary 

 magma is basalte, that pyroxene andesite and picrite are direct differ- 

 entiates from it, and that the alkaline rocks may possibly be due to the 

 solution of small proportions of limestone. There is a nine-page alpha- 

 betic list of the various islands with the different rock types occurring 

 on each, and a list giving the number of islands from which the various 

 rocks have been reported. 



Daly, Reginald A. "The Geology of Pigeon Point, Minnesota," 

 Amer. Jour. Sci., Vol. XLIII (191 7), pp. 423-48. Figs. 5. 

 Believes that the "red rock" originated through both assimilation 

 and differentiation rather than through the differentiation of a wholly 

 primary magma, but says a final decision concerning its origin must for 

 the present be delayed. 



Daly, Reginald A. " Metamorphism and Its Phases," Bull. Geol. 

 Soc. Amer., Vol. XXVIII (1917), PP- 375-4i8. 



Proposes to classify metamorphic processes as follows: 

 A. Regional metamorphism. 



I. Static metamorphism. 



a) Stato-hydral or hydrometamorphism (low temperature). 



b) Stato-thermal or load metamorphism (high temperature). 



