28 
MUSEUM BULLETIN NO. 11. 
and left hanging in the air. Such parallel draws are seen all 
along Hall creek, and one especially well developed is to be seen 
in the West Fork bottom on the northern edge of the map. 
Here there is a dry canyon about 80 feet deep paralleling the 
river, and on the west side of it. 
Relation of Shatter Belts to Stream Courses. 
The bottom or side of a stream course is often the outcrop 
of a belt of shattering which trends in the same direction as its 
valley trench at that point. This has been more especially seen 
in the case of small valleys within the quartz diorite and quartz 
monzonite batholiths. On Wallace mountain the outcrops of 
belts of shattering and of strong faulting occur along the bottom 
of small gullies on the mountain side. The faulting and shat- 
tering was in this case seen in mine tunnels under the gullies. 
In two cases dykes were seen to be displaced along planes fol- 
lowing the bottom of small gullies, one in quartz monzonite and 
the other in quartz diorite. The relation between fault lines 
and valley courses has been discussed on page 24 in describing 
the accordance between topography and structure upon the up- 
lands. 
Shapes of the Valleys in Cross Section . 
According to the shape of their cross sections one may 
classify the valleys into three types. There is a U-shaped or 
glacial type, a canyon type with a typical V-shape, and an up- 
land draw type which resembles a very much flattened V in 
cross section. 
The U-shaped valleys have steep sides and a broad flat 
terraced bottom (Figure 2, profile 4). As one looks up or down 
some of the straight stretches of these U-shaped valleys their 
two sides appear as two planes steeply inclined to the floor like 
the two sides of a gigantic flume. The continuity of these planes 
is broken by the gaps made by side streams, but between these 
gaps the side spurs end abruptly in one of the planes, and look 
as if their front ends had been neatly sawed off. The West Fork 
