PHYSIOGRAPHY OF THE BEAVERDELL MAP-AREA, 
9 
higher hills to the lower valleys run from 160 to 300 feet to the 
mile, and differences of elevation from 1,500 to 2,000 feet occur 
constantly within 10 miles of each other, but seldom exceed 
those figures. The regional slope both along and across ridges 
varies considerably from place to place within the same area; 
but slopes measured upon interfluves which are not much cut 
up by canyons show a general uniformity. Thus slopes measured 
from hilltop to hilltop across a system of parallel ridges in the 
Beaverdeli area generally run from 200 to 300 feet to the mile, 
although upon the Nipple Mountain interfluve the slopes go 800 
feet to the mile (Figure 2, profiles 1 and 2). Slopes measured 
along ridges show about the same grade and variation (Figure 2, 
profiles 3 and 4). The regional slope in the Tulameen area 
averages over 300 feet to the mile (Plate II). In the Kamloops 
map-area the regional slope is about 160 feet to the mile, though 
here as elsewhere there are many local slopes which differ from 
the average. In the western half of the Shuswap area they are 
somewhat higher and vary more widely. This section of the 
upland is in general flatter than in the other two southern areas 
examined (Figure 2, profile 7), and this corresponds to Dawson’s 
statement that the plateaus decrease in ruggedness to the north. 
A study of profiles drawn from three of the topographic maps, 
Figure 2, shows that there is generally a regional slope upon the 
upland down toward the deep valleys which now separate the 
ridge-like upland blocks. In the Tulameen area the profiles do 
not everywhere show the same degree of accordance between 
regional upland slope and main drainage lines (compare profiles 
5 and 6 in Figure 2). Here parts of the upland surface appear 
to be tilted to the east away from the mountains, as can be seen 
in profile 6. 
Local Irregularities in Slope. 
Many local slope irregularities occur upon the upland surface 
in all three regions under discussion. In the Beaverdeli quad- 
rangle such irregularities are chiefly connected with the Tertiary 
volcanics, although found developed upon any type of under- 
lying rock. They are not as dominant features as the gentler 
slopes. 
