580 - EDWARD STEIDTMANN 



The rocks of the Rocky Mountain geosynclinal are believed by 

 Daly to be largely derived from the pre-Beltian. He finds that the 

 microscopic characteristics of the feldspars in the sediments are 

 identical with those of the granites, sills, and dikes which intrude 

 the Shuswap series. The extraordinary fine grain of the quartzites 

 he attributes to their derivations from metargillites, phyllites, and 

 greenstone schists. 



Daly does not care to have the term Algonkian applied to 

 the pre-Cambrian of the Shuswap Lakes region, since it would 

 include two series which are separated by a well marked uncon- 

 formity. 



Darton^ records a few observations on the distribution of the 

 Vishnu and Grand Canyon series in western New Mexico and 

 northern Arizona. 



Emmons^ states that a complex of pre-Cambrian granites con- 

 stitutes the basement upon which later sedimentary and igneous 

 rocks of the Cananea district were superimposed. 



Emmons^ states that the oldest rocks of the Little Rocky 

 Mountains between the Missouri and Milk rivers consist of pre- 

 Cambrian quartzite by intrusive porphyry. 



George and Crawford'' find that the pre-Cambrian rocks of the 

 Hahn's Peak region of Routt County, Colo., as a complex of schists, 

 gneiss, gneissoid granite, and granite with isolated patches of 

 quartzite. 



Henderson^ describes the pre-Cambrian rocks of the Front 

 Range of Colorado, as consisting of Archaean granite and gneiss, and 

 an Algonkian quartzite, outcropping from South Boulder Canyon 



' N. H. Darton, " A Reconnaissance of Parts of Western New Mexico and Northern 

 Arizona," Bull 435, U.S. Geological Survey, 1910, pp. 14-15- 



==8. F. Emmons, "Cananea Mining District of Sonora," Econ. Geol., V, No. 4 

 (i9io),3i2-. 



^W. H. Emmons, "Gold Deposits of the Little Rocky Mountains, Montana," 

 Bull. 340, U.S. Geological Survey, 1907, pp. 96-116. 



1 R. D. George and R. D. Crawford, "The Hahn's Peak Region, Routt County, 

 Colorado," Colo., Geol. Surv., ist Rept., 1908, pp. 189-229, i pi., 1909. 



5 Junius Henderson, "The Foothills Formations of Northern Colorado," Colo. 

 Geol. Surv., ist Rept., pp. 149-85, 1909. 



