PETROLOGICAL ABSTRACTS AND REVIEWS 591 



Drysdale, Charles W. Geology of Franklin Mining Camp, 

 British Columbia. Mem. 56, Geol. Surv., Dept. Mines. 

 Ottawa, 1915. Pp. 246, pis. 23, figs. 16, bibliography. 



A report on a mining camp in the Yale District in south-central 

 British Columbia. The Franklin group contains the oldest rocks in the 

 district, consisting of metamorphic tuffs, quartzites, and argillites, the 

 latter carrying Paleozoic fossils. The rocks may represent early marine 

 coastal conditions of sedimentation and igneous activity prior to the 

 submergence and eastward transgression of a Carboniferous sea. At 

 the close of the Paleozoic the main folding and metamorphism of the 

 region took place, and the Franklin District thereafter remained above 

 the sea. During the Jurassic period there came the intrusion of a grano- 

 diorite batholith beneath a considerable cover of sediments. It did not 

 reach the surface. The Cretaceous period was one of long-continued 

 denudation, laying bare great thicknesses of Paleozoic rocks and even 

 exposing the underlying Jurassic batholith in places. At the close of the 

 Mesozoic the whole Cordillera was uplifted and the Valhalla granite 

 was probably intruded. The early Tertiary was a period of regional 

 sinking accompanied by some volcanic activity. It closed with the 

 tilting of the Kettle River formation, and a new cycle of erosion started. 

 At this time also there came the intrusion of monzonite. During the 

 Miocene there came intrusions of syenite, followed by pyroxenite and 

 augite-syenite, pulaskite-like dikes, and trachyte flows. Regional uplift 

 closed the Tertiary. During the Pleistocene all except a few of the 

 highest peaks of the Cariboo Range were covered by the Cordilleran ice 

 sheet. 



A number of chemical analyses of the igneous rocks are given. 



Eskola, Pentti. On the Petrology of the Orijarvi Region in 

 Southwestern Finland. Bull. com. geol. Finlande, No. 40. 

 Helsingfors, 1914. Pp. 277, pis. 6, maps 2, figs. 55, bib- 

 liography. 

 This interesting bulletin gives an account of the petrology of a series 

 of Archean metamorphic rocks in the vicinity of Orijarvi. After a short 

 geologic history of the region, the author gives careful and detailed 

 petrographic descriptions of various granites, magmatites, pegmatites, 

 diorites, gabbros, hornblendites, aplites, peridotites, amphibolites, 

 leptites, and limestones. He then describes the exogenic contact-zones 

 of the oligoclase-granite, and gives petrographic determinations of the 



