222 Dr James Hector on the Physical Features of the 
the want of moisture in early spring, is the immediate cause 
of this barrenness. The little snow which falls on the open 
plain is at once swept off by the wind and evaporated during 
the winter, so that in spring the clear powerful sun at once 
bakes the soil and prevents the germination of seeds. 
The weather experienced in the Rocky Mountains was very 
irregular, with a great daily range of temperature. Thus, 
in the end of August the thermometer during the night was 
as low as 14° at an altitude of 6000 feet, and almost every 
night it fell considerably below the freezing point, although 
during the day it often reached 70° to 80°. In the valleys of 
the eastern slope the amount of rain-fall is very small com- 
pared to that on the first part of the descent to the west, when 
fine weather is the rare exception even in September. This 
only applies, however, to the mountains north of the fifty-first 
parallel of latitude, south of which, for some reason, the rain- 
fall on the western slope in the valley of the Kootani River 
must be much less, judging both from the experience of two 
seasons and from the nature of the vegetation, which is of 
the arid type. 
On the eastern slope, throughout the entire summer, there 
are occasional falls of snow at altitudes above 5000 feet; but 
snow never lies deeply at any season. It is only on the various 
“heights of land” which have an altitude of from 6000 to 
7000 feet, and for the first few miles of the western descent, 
that snow appears to accumulate in the valleys in large quan- 
tities—sometimes to the depth of 16 to 20 feet. The higher 
valleys of the central mass of the mountains are occupied by 
glaciers, some of which are of very considerable size, even when 
resting on the eastern slope. They are, however, fed princi- 
pally by the snows that accumulate on the western slope, so. 
that when ranges equally high are cut off from the influence of 
the western moisture, no glaciers have been formed, This 
exactly conforms to what has been observed by Dr Hooker and 
others regarding the diminished altitude of the snow-line as 
the nearest seaboard to a range of mountains is approached. 
In the Latitude of 49° the country to the west of the Rocky 
Mountains is very rugged and mountainous for the whole dis- 
tance to the Pacific coast. South of that parallel, however, 
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