diller.] A MIOCENE PENEPLAIN. 15 
If the Wymer beds on the border of the Klamath peneplain should 
turn out to be Pliocene and those of the Hay Fork stage later than 
the Miocene, the Miocene would be largely excluded from the sequence. 
THE KLAMATH PENEPLAIN. 
The Klamath Mountains are characterized in many places by flat- 
tisli or gently rounded summits and an approximate accordance in 
the altitudes of even-crested ridges, giving to these highlands the 
aspect of a dissected plateau. The upper portions of the principal 
divides, after attaining a considerable altitude above the sea, have 
iu places broad lops on which the relief features are terraces or low, 
rolling hills. Sharp peaks above this level of gentle relief are found, 
with rare exceptions, only among the highest parts of the range. The 
original more or less irregular plateau surface, of which we now have 
only remnants, for convenience of reference may be for the present 
assumed to be due to a form of planation, and designated the Klamath 
peneplain, although its approach to a plain is in places not clearly 
marked, because (1) the original prominences were not completely 
reduced to the general level, and because (2) it has been so warped 
and broken by differential change of level as to partially obscure its 
original character. 
REMNANTS OF THE KLAMATH PENEPLAIN. 
In the northern part the Klamath peneplain is well marked in the 
densely forested summit of the Coast Range. Seen from the vicinity 
of Roseburg, Oreg., the range presents an even crest (PI. Ill) rising 
to an altitude of from 2,500 to 3,000 feet. From the summit of this 
bold escarpment, which faces the east, the crest is seen to be the edge 
of a broad plateau whose smooth or gently rolling surface is deeply 
trenched by streams. In the cross canyon of the range its synclinal 
structure of Eocene sediments is well displayed and the flattish sum- 
mit is clearly a plain of erosion. Extensive general views of this por- 
tion of the plateau are difficult to obtain on account of the gentle 
relief of its general surface and the heavy forest covering. One of 
the best views of the east front may be had from Tyee Mountain, 
which has an altitude of 2,655 feet. The plateau has a gentle 
inclination westward. Its western edge, although rising nearly 2,000 
feet above the sea, is much less distinct than its eastern. To the south- 
west the Klamath peneplain rises gradually nearly to the limit of 
the Eocene sandstone in Eden Ridge and Blue Knob, on Rogue River, 
where it has an altitude of 3,787 feet. The crest of this portion of the 
range ma} 7 be seen from Barklow Mountain, at the head of the South 
Fork of Sixes River. The uniform character of the arenaceous sedi- 
ments gives the peneplain considerable uniformity. Going south 
near the coast, before reaching Rogue River, one finds the older and 
