MALA SPINA GLACIER. 223 



is known to be about an hundred inches. In the vicinity of 

 Mt. St. Elias it is probably even greater than this. The pre- 

 vailing winds are from the south, at least in summer, and are 

 laden with moisture which is precipitated when the mountains 

 are reached. To the north of the mountains the climate is far 

 different from what it is on the coast. The summers are short 

 and hot and the winters marked by extreme severity ; the rain- 

 fall is small throughout the year and perennial snow is not seen 

 even on mountains four or five thousand feet high and situated 

 near and even north of the Arctic Circle. 



On the mountains facinof the ocean the winter snow extends 

 down to sea level but melts during spring- and summer so as to 

 form a well defined boundary, or " snow line," which recedes from 

 the coast as the warm season advances. In August and Septem- 

 ber it has an elevation of about 2,500 feet, corresponding on the 

 glaciers with the lower limit of the neves. The regions below and 

 above the snow line are in marked contrast. From the ocean up 

 to an elevation of from 2,500 to 3,000 feet in summer, every 

 island in the ice as well as the low lands along the coast and 

 even the moraines on the lower border of the Piedmont ice -sheet, 

 are covered with luxuriant vegetation, and are frequently brilliant 

 with banks of flowers. Above the snow line except on occa- 

 sional sunny slopes at comparatively low elevation, where Alpine 

 flowers thrive, all is desolate, lifeless winter. The well known 

 features characteristic of glacial ice and neve snow are sharply 

 defined by the same horizon. In the higher mountains snow 

 storms are frequent even in summer, and at elevations exceeding 

 about 13,000 feet rain never falls and the snow is fine and dry. 

 On the mountain tops the snow does not soften, even on hot 

 summer days. Its indefinite accumulation is prevented by ava- 

 lanches and by its being blown away. 



The relief of the St. Elias region is due largely to displace- 

 ments. The mountains are in many instances formed of tilted 

 blocks bounded by faults, and the prevailing structure approaches 

 the Great Basin type. The effects of pre -glacial stream erosion 

 are not distino-uishable and in manv instances the ice drainaafe is 



