GLACIATION OF SAN FRANCISCO MOUNTAIN, ARIZONA 1 



WALLACE W. ATWOOD 

 The University of Chicago 



During the summer of 1904 the slopes of San Francisco Mountain 

 were examined with some care, and to the northeast of the main 

 peaks records of ancient glaciation were found. The latitude of 

 San Francisco Mountain is approximately 35 21', and the records 

 of glaciation found here may possibly be those of the southernmost 

 ice which existed in this country during the Pleistocene period. 



San Francisco Mountain is in the north-central portion of Arizona, 

 about ten miles north of the village of Flagstaff. It is of volcanic 

 origin, having been built by numerous outpourings of lava and by 

 explosions of fragmental material. The ancient crater of this moun- 

 tain is bordered on the north, west, and south by a series of peaks 

 (see Fig. 1) which are remnants of the once higher rim of the crater. 

 These peaks rise to elevations of from 12,250 feet to 12,794 feet above 

 sea-level, and nearly 7,000 feet above the general level of the plateau 

 on which the mountain stands. To the east the rim of the crater 

 is wanting, and the one stream which drains the central portion of 

 the mountain flows through this opening or gap, and then, turning 

 to the north, descends quickly to the alluvial deposits about the base 

 of the mountain. 



The general topographic relations, shown in Fig. 1, indicate that 

 there is today a well-protected catchment area for rain and snow. 

 The high walls on the south and southwest of the basin give the 

 most favorable conditions, in this latitude for the preservation of 

 snows. The floor of the crater varies in elevation from 10,000 to 

 11,000 feet, and is bordered by the bold, and at places, precipitous, 

 slopes of the lofty peaks which surround it. The dimensions of the 

 catchment basin are best seen in Fig. 1. The total possible area of 



1 The work reported in this article was done in company with a party of students 

 from the University of Chicago, and the author is indebted to the members of the party 

 for assistance in collecting data. 



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