THE ARAPAHOE GLACIER 33 



ord had been kept at the glacier itself. Furthermore, the cirque 

 containing the glacier is in full sight from the brow of University 

 Hill in Boulder, and during the autumn of 1902, winter of 1902- 

 3, and spring of 1903, the writer watched the peak as closely as 

 possible, and was much impressed with the frequency with which 

 clouds gathered in the glacial amphitheater when all was clear 

 elsewhere. The snows began early in September and continued 

 until late spring. 



It seems possible that the significance of the silt on the 

 morainal bowlders in 1902 may have been misunderstood, as a 

 similar condition was observed in 1903 ; and yet it is hardly pos- 

 sible that the glacier flowed out over the moraine and then melted 

 back to the base of the moraine between September, 1902, and 

 September, 1903. A possible explanation suggests itself. The 

 accumulation of snow on the glacier each year is known to be 

 enormous, a great many feet in depth. The westerly gales are 

 known to carry from the rim of the cirque to the glacier large 

 quantities of dust and finely comminuted vegetable matter dur- 

 ing every dry, windy period, which periods are common in that 

 region and at that altitude. The accumulated snows containing 

 such dust and vegetation cover the moraine to a great depth in 

 winter. As the snow melts in the spring, the debris gradually 

 accumulates at lower and lower levels, until finally it is left as 

 silt on the tops of the bowlders and all over the moraine. Unfor- 

 tunately, we brought none of it with us, and failed to make a 

 .minute examination of it under a good lens. The cause may be 

 sufificient to account for the phenomena, but the subject is worthy 

 of more extended investigation before announcing definite con- 

 clusions. 



Junius Henderson. 



Museum, University of Colorado, 

 Boulder, Col. 



