176 GUIDEBOOK. OF THE WESTERN UNITED STATES. 
The canyon is short and north of the ridge lies Selah Valley, one 
of the prettiest valleys in this part of the country. The land is rolling 
or even hilly along the sides of the valley, but water 
Selah, is carried in a high-line canal, so that all the hills and 
eerste slopes below it are highly cultivated, and orchards 
cael extend as far as the eye can see. The basalt dips 
under the valley, but a little farther north it rises 
above water level, and the river has cut a sharp canyon with vertical 
walls from 50 to 70 feet high. The main canyon, which begins near 
milepost 99 (see Pl. XXIV, A) is cut through three separate but 
parallel ridges of basalt, each of which was produced by a low up- 
arching of the lava, as shown in figure 36. At the entrance to the 
deeper part of the canyon the great sheets of lava, each representing 
an individual flow, rise more steeply toward the north, their dip 
(20° or 25°) corresponding in a general way with the south slope of 
the ridge. The walls of the canyon increase in height until at mile- 
post 103, where the railway crosses the river, they are nearly 2,000 
feet high. Here the rocks are about horizontal, indicating that this 
FIGURE 36.—Fold in basalt north of Roza, Wash., as seen from a point near Wymer, looki theast. 
is the middle (axis) of the fold, from which the beds dip in opposite 
directions. North of the axis the layers of basalt dip 30° or 35° to 
the north. 
The northward dip continues to Roza, near milepost 106, where 
two lateral valleys entering on opposite sides of the river mark the 
depression or trough between the ridges. Toward the east the ridge 
south of Roza extends for a long distance, but in the other direction 
it dies down rapidly, and in a distance of 5 or 6 miles has disappeared. 
Beyond Roza the beds of lava rise northward about 30° up the slope 
of Umptanum Ridge, which is a few hundred feet higher than the one 
ce south of Roza. The axis of the fold is reached about 
7 milepost 109, and beyond this point the beds can be 
bt Petre et seen to bend over in a great arch; but the traveler is 
: so close to the rocky wall that it is impossible for him 
to obtain a satisfactory idea of the size or shape of the fold until he | 
has gone some distance past it. At Wymer siding, between mileposts 
110 and 111, a good view of the fold on the east side of the river can 
be obtained by looking directly back from the rear of the train. 
(See fig. 36.) From this point the fold is seen to be unsymmetrical, 
with the steepest dips on the north side. 
