28 TOPOGKAPHIC DEVELOPMENT OF KLAMATH MOUNTAINS, [bull. 190. 
principal terrace, having a broad plain at least a mile wide, ranges 
from 850 to 925 feet and corresponds closely to the 1,000-foot terrace 
seen elsewhere. The next largest terrace occurs at 250 feet and is 
well developed near Lone Ranch. This terrace is the coastal plain, 
and ranges in elevation from 250 feet at the northern end to almost 
sea level below Crescent City in California, a distance of 50 miles. 
There are small sea cliffs and minor terraces on this plain, but none of 
sufficient prominence to break the continuity of the plain, except 
along Smith River, where a broad flood plain with rich farms is a 
notable feature. The 1,000-foot terrace is well marked nearly to 
Chetco River, but south of that river the coastal plain lies at the foot 
of the plateau escarpment, as shown in PL XI, rising to an altitude 
of 1,700 feet. This plateau escarpment has a slope of 17|°, and the 
absence of all clear traces of the terraces so well marked a few miles 
farther north suggests that it is a fault scarp. Onty angular frag- j 
ments were found along the east edge of the plain at the foot of this 
steep slope, where a beach would be expected if the plain developed 
after the faulting. 
Crossing the Windchuck and entering California, one finds that the 
topography changes as Smith River is approached. The plateau front 
becomes less prominent and retreats to 5 miles from the coast, giving 
the coastal plain an extensive development as far south as Crescent 
City. This large coastal plain, less than 50 feet above tide, is due 
doubtless to the presence of soft Neocene rocks, remnants of which 
occur on the coast near Point St. George, as well as on the edge of the 
Klamath peneplain at an elevation of about 2,100 feet. An inter- 
mediate terrace was noted east of Crescent City at an elevation of 
about 700 feet, and two others of small extent north of Smith River 
at 1,350 and 1,450 feet, with small swampy patches like those of the 
coastal plain. 
SOUTH OF CRESCENT CITY. 
South of Crescent City 3 miles the coastal plain, which lies scarcely 
10 feet above the sea level, runs out and the road mounts to the 
plateau formed apparently by the Sherwood peneplain at an altitude 
of about 1,300 feet. The seaward slope of the plateau front is 28° to 
32° and shows no prominent traces of terracing below 1,000 feet. At 
that level, rising to the southeast, there is a densely wooded plain of 
considerable extent, connected by terraces, with higher levels farther 
eastward. Descending toward Wilson Creek the road here and there 
runs close to the steep slope overlooking the sea, and at a number of 
places crosses ravines of tributaries to Wilson Creek, which have been 
beheaded at an elevation of over 800 feet by the landward advance 
of the sea cliff. Whether this beheading is due to simple advance by 
marine erosion or to faulting along this bold slope is not certain, but 
most likely the latter, for if due to erosion alone there must be some 
cause, not readily seen, for such vigorous local action. 
