Abstracts. 



Geological Atlas of the United States. Folio 30, Yellowstone National 

 Park, Wyoming, i8g6. 

 The Yellowstone Park folio, recently issued, consists of six pages 

 of descriptive text, three pages of illustrations, four topographic sheets 

 (scale I : 125,000) and four sheets delineating the areal geology of the 

 region. 



The general descriptive text, giving a succinct narrative of the geo- 

 logical history and development of the park country from the time of 

 the earliest continental land surfaces up to and including the hydro- 

 thermal phenomena as seen today, was written by Arnold Hague, 

 o-eologist in charge. It is followed by an account of the sedimentary 

 rocks, from the earliest Cambrian deposits to the Tertiary conglomer- 

 ates, by Walter Harvey Weed, and a brief petrographical descrip- 

 tion of the igneous rocks, by Joseph Paxson Iddings. The area of 

 country covered by the Yellowstone National Park folio lies between 

 parallels 44° and 45'' and meridians 110° and 111°. It is situated in 

 the extreme northwest corner of Wyoming. By far the greater 

 part of the park is included within the area of the four atlas sheets, 

 but a narrow strip lies to the northward in Montana, and a still nar- 

 rower strip extends westward into Idaho and Montana. In the organic 

 act establishing the park. Congress declared that the reservation was 

 "dedicated and set apart as a public park and pleasure ground for the 

 benefit and enjoyment of the people." Owing to the marvelous dis- 

 play of geysers and hot springs, and such remarkable physical features 

 as the Grand Canyon and Yellowstone Lake, this folio possesses more 

 than ordinary interest to geologists. 



The central portion of the Yellowstone Park is a broad volcanic 

 plateau, with an average elevation of 8000 feet, surrounded on nearly 

 all sides by mountains rising from 2000 to 4000 feet above its general 

 level. The continental watershed crosses the park, separating the 

 w^aters of the Atlantic from those of the Pacific, the Missouri and the 

 Columbia, by the way of the Yellowstone, and the Snake, finding their 



sources on this plateau. 



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