130 DESCRIPTIVE GEOLOGY. 



SECTION V. 

 PAEK RANGE. 



BY ARNOLD HAGUE. 



Physical Description. — The Park Range forms the third and last 

 great Archaean uplift of the Rocky Mountain system included within the 

 limits of this survey, extending from about the latitude of 41° 20', in an 

 unbroken line, far to the southward into Central Colorado. Within the 

 boundaries of the map, the range embraces, in a north and south line, about 

 70 miles. In width, it varies considerably; the southern end, opposite the 

 North Park, measuring only 12 to 15 miles from east to west, while to the 

 northward, in the region of Pelham Peak, its broadest expanse, it reaches 

 from 30 to 35 miles. 



In its topographical features, the Park Range presents much less that 

 is grand and rugged than the Colorado, and much less diversity of structure 

 and intricate drainage than the Medicine Bow; and, while its general eleva- 

 tion is as high as the other ranges, the culminating peaks are much lower, ^ 

 only one. Mount Zirkel, attaining an altitude of over 12,000 feet above sea- 

 level. The highest peaks in the range are Mount Zirkel, 12,126 feet, and 

 Ethel Peak, 11,976 feet, on the western rim of the North Park; 'Pelham Peak, 

 11,524 feet, a picturesque, graceful summit, just north of the Colorado line, 

 in the Territory of Wyoming; and Grand Encampment Mountain, 11,063 

 feet, in the northern end of the range, at the head of Battle and Savory 

 Creeks. 



From the southwest comer of the North Park, the trend of the range 

 is nearly due north and south for 45 miles, with a narrow plateau-like 

 summit along the eastern edge, falling oif with gentle undulating slopes 

 to the westward, but terminating in a somewhat abrupt wall toward the 

 depression known as the Park. This wall, to the north of Mount Zirkel, 

 is broken by a long narrow spur that puts out from the main ridge in a 

 southeasterly direction into the Park, while a nearly parallel ridge, still 



