EXTINCT AND EXISTING GLACIERS OF COLORADO 53 



feet in altitude, with lobes of ice extending off on each side down the 

 valleys for several miles, affecting about one-half of the counties of 

 the state. It seems probable that from lo to 20 per cent of the state 

 was once covered with glacial ice and neve. The total area of exist- 

 ing glacial ice and neve definitely reported would not exceed ten square 

 miles. 



Maps. — Owing to their small scale and the lack of definite data, 

 the accompanying maps (Figs. 2 and 3) are very much generalized, 

 so as to give only a very general idea of the distribution of the glaciers. 

 Most reports are indefinite and nearly all are unaccompanied by maps. 

 The shaded outlines indicating glaciated regions necessarily include 

 ridges and other areas which were not covered by ice, and other areas 

 covered by the glaciers are not included. Only a large, detailed map, 

 based upon much more field work, could correctly represent even the 

 known facts, and extensive areas are wholly unreported and unknown. 



Northern Front Range and Medicine Bow District. — This whole 

 region was covered with glaciers for a breadth of about 16 miles. 

 The southern Medicine Bow glaciers extended down to the edge of 

 North Park, large ones extended down both branches of the Cache 

 la Poudre and Big Thompson, one reaching an altitude of about 

 6,500 feet, and some on the west side of the range reaching the foot- 

 hills of Middle Park.^ The South St. Vrain and associated glaciers 

 extended down to an altitude of about 9,000 feet,^ leaving a fine 

 series of moraines within a few hundred yards of Ward. Just west 

 of Ward the glaciers overrode the hills and the debris indicates a depth 

 of ice of probably at least 300 to 400 feet. The main glacier is not 

 quite extinct and is elsewhere described as Isabel Glacier. Albion 

 Glacier, north of Arapahoe, has likely retreated very recently, glacial 

 polish and striae still showing on rocks which are of such character 

 as to weather readily. It is still represented by crevassed neve at 

 the head of Albion Gulch. North Boulder Glacier, represented by 



' King, Clarence, " Systematic Geology," U.S. Geol. Sum. 40th Parallel, Vol. I, pp. 467, £f; Cooper, 

 William S., "Alpine Vegetation in the Vicinity of Long's Peak, Colorado," Botanical Gazette, Vol. XLV, pp. 

 320-24, 1908; Orton, Edward, Jr., "The Mills Moraine, with Some General Remarks on the Glaciation of 

 the Long's Peak Region of Colorado," Science, N.S., Vol. XXIX, pp. 751-52, igog. 



' Ramaley, Francis, and Robbins, W. W., "Redrock Lake, Near Ward, Colorado," Univ. Colo. Studies, 

 Vol. VI, pp. 135-68, 1909. 



