378 OSCAR H. HERSHEY 
width of this valley is due to the rather soft nature of the for- 
mations, but the fact remains that all other valleys of this region 
carved into the same formations are relatively narrow and have 
the gulch form, which, inthe Klamath region, is the character- 
istic of the Pleistocene valleys. 
Scott valley terminates as abruptly at the northern or down- 
stream end as at the other, and Scott River drains it through a 
narrow gorge which is only partly explained by the hardness of 
the formations cut into. This valley has no known Neocene 
remnants, as its floor is so elevated (about three thousand feet 
above the sea) that subsequent erosion may have completely 
removed them. Its identification as Neocene rests on its large 
size and its abrupt termination at both ends. 
The Hay Fork valley, in southern Trinity county, has a length 
of about eleven miles and an average width between one and 
two miles. Its course is a little south of west, or obliquely. 
across the strike of the formations, which here occur in parallel 
belts as they have been folded and faulted. The strata of the 
metamorphic rocks stand at a high angle, usually approximating 
to the vertical. The flat floor of the valley has an altitude at 
Hay Fork village of about 2,200 feet above tide and the sur- 
rounding mountains rise to an average height of about 4,000 or 
4,500 feet above the sea. The valley is, therefore, quite a deep 
trench and a prominent feature of the topography. Its walls 
are comparatively steep. The form of the valley shows dis- 
tinctly that it is the result of ordinary stream erosion. There 
would be nothing remarkable about this valley if it were not 
that it is the only one of the kind in that portion of the country. 
All the neighboring valleys are relatively narrow and of the 
gulch type. Hay Fork stream enters the valley on the south 
about four miles from its eastern end, coming out of a narrow, 
gorge-like valley. Above this point the Hay Fork valley is 
occupied by an insignificant stream which seems out of place in 
the large valley. As there is nothing in the structure to explain 
the great contrast in size and shape of the valleys, we naturally 
conclude that the broad Hay Fork valley belongs to a separate 
and older system. 
