502 abstracts: geology 



GEOLOGY. — The Cosna-Nowitna region, Alaska. Henry M. Eakin. 



U. S. Geol. Survey Bull. 667. Pp. 54, with maps and illustrations. 



1918. 

 The Cosna-Nowitna region, which lies between Mt. McKinley and 

 Yukon River on the north, is stratigraphically and structurally very com- 

 plex. The geology presents much variety and many of the rock ter- 

 ranes recognized in this field can not yet be definitely correlated with the 

 formations in other parts of the Yukon basin. Yet the age of at least 

 two formations — the Ordovician and Devonian limestones — has been 

 pretty definitely established, and these determinations will help to solve 

 some of the stratigraphic problems of central Alaska. The correlation 

 of the pre-Ordovician metamorphic sediments of the Cosna-Nowitna 

 region with the Birch Creek schists of the Yukon-Tanana region also 

 seems justified. There are some large areas of volcanic rocks and 

 smaller ones of intrusive granite. The dominant trend of the structural 

 features is northeasterly. The general events of the tectonic history 

 of thfe region appear to include extensive crustal deformation in pre- 

 Ordovician, post-Ordovician, post-Devonian, and probably late Meso- 

 zoic or early Tertiary time. The development of the present topog- 

 raphy of the region is discussed. 



R. W. Stone. 



GEOLOGY. — The coalfields of the United States. General introduction. 

 Marius R. Campbell. U. S. Geol. Survey Prof. Paper 100-A. 

 Pp. 1-33. 1917. 

 A general introduction to a series of papers describing the coalfields 

 of the United States. This paper defines the various kinds of coal, 

 classifies and defines the coal areas, gives the production and estimates 

 the tonnage of coal in the United States, and gives analyses of repre- 

 sentative coals from many States. 



R. W. Stone. 



GEOLOGY. — Cannel coal in the United States. George H. Ashley. 

 U. S. Geol. Survey Bull. 659. Pp. 126, with maps, sections, and 

 illustrations. 1918. 

 This report defines, describes, and classifies cannel coal, and discusses 

 its mode of occurrence, uses, production, value, and distribution. Can- 

 nel coal is one of the richest substances in hydrocarbons known, and it 

 was because of the demand for the lighter hydrocarbons for use in chemi- 

 cal industry that this report was prepared. 



R. W. Stone. 



