19"2 GEOLOGICAL SURVEY OF THE TERRITORIES. 



able weather and a lack of time prevented us from spending as much 

 time there as we should have wished to expend upon it. 



Another characteristic of that group dare not be overlooked, as its 

 consequences have a more or less direct bearing on geognostic features. 

 Owing to the position that this high mass of peaks takes to the adjoin- 

 ing low country, rain or snow fall is very frequent. During the entire 

 summer, whenever we had a view of that section of country, it could 

 almost invariably be noticed to rain or snow, and during our trips 

 through its mountains we had ample opportunity to verify the observa- 

 tions made from a distance. 



It is apparent that, in a case of that kind, glaciers might form that 

 would have considerable influence upon the shaping of the configuration 

 in detail; although the falling of debris will frequently produce results 

 similar to those furnished by moving ice. A number of points were 

 observed where the rounding off and striation of the sides of canons or 

 gorges, and the deposition of large, washed bowlders, left no doubt as 

 to their origin. This was observed particularly well on the headwaters 

 of Vallecito Creek, northwest of Mount Oso (station 23). Near station 

 38 another locality showing the effects of glacial action was observed. 

 The hard quartzite strata exposed their edges, having a dip of about 23° 

 to the northwest. From the north and south ridge upon which the 

 station was located, the ice had come down, rounded off all the sharp 

 edges of the quartzite strata, and had polished and striated such por- 

 tions that were too high to be covered. Three or four of these small 

 glaciers must have moved side by side, separated by narrow ridges. 

 Toward the main' ridge the ground is scooped out deeper than some 

 distance from it, and the heads of the upturned strata are worn away 

 more at the end facing it. Numerous small lakes, or, in some places, 

 swamps, are found in the holows produced by the passage of ice and 

 rocks. 



As mentioned above, some of the granitic rocks in the Animas Val- 

 ley, above Animas City, have the characteristics of roches-moutonnees. 

 Below Animas City there is a narrow valley about one and a half miles 

 wide on average, and ten miles long, the Animas Park, so-called. The 

 soil of this valley is composed of drift, originating to great extent in the 

 granitic areas. Although I should not be prepared to attribute its 

 presence entirely to glacial action, it seems probable that the ice- masses, 

 which certainly existed at one time higher up along the river, n-.ight 

 have extended, at least periodically, downward, and thus may have 

 added their share to the transportation of erratic material. As is al- 

 ways the case in a comparatively level valley, where the character of 

 the river-bed offers but little resistance to the eroding influence of flow- 

 ing water, here, too, the river gradually meanders through it in many 

 curves, and it cannot be denied that the actiou of the waters alone 

 carried perhaps repeatedly over the same ground would be fully able to 

 produce the result observed. 



In a country where the winters are very severe, where the precipita- 

 tion is considerable, and where the character of the mountains and 

 caiious is sq„ singularly favorable to allow by far the greater part of the 

 water to flow off, local temporary glaciers may be formed more readily 

 than where the cited conditions are wanting. Should this be continued 

 for any length of time, the result will be a series of phenomena analo- 

 gous if not identical with those observed in regions where persistent 

 glaciers exist. The absence of any well-developed moraines at the 

 localities just described, inclines me to the view that such may have 

 been the case in these instances. 



