Rcz'iezu of Recent Geological Literature. 257 
Bulletin of the United States Geologieal Survey No. i()6; Topographic 
Development of the Klamath mountains. By Joseph S. Diller. 
The Klamath mountains extend north and south from the 43d paral- 
lel in Oregon, to the 40th in California. On the northwest they are 
separated from the coast by the Coast range of Oregon, and on the south 
west by the Coast range of California. The Cascade and Sierra Nevada 
ranges bound them on the east and in the southeast the Sacramento 
river has pushed its valley to their foothills. 
Going as far back as Cretaceous times there is evidence that the 
Sierra Nevada reigon was land and that its streams were carrying sedi- 
ments which were deposited on the submerged Klamath mountain region. 
Subsequently elevation brought the sediments above sea level and erosion 
removed the greater part of them. Beginning at the close of the Eo- 
cene times, there can be traced, in the Klamath mountain region, six- 
teen stages of development which took place during Miocene, Plio- 
cene and Pleistocene times. 
Stage I. — In early Miocene times an uplift took place and initiated 
the cycle of erosion which formed the Klamath peneplain. Its record 
is now to be found in the flat tops of the dissected plateau which forms 
the Klamath mountains. Its formation was due to erosion which was 
subaerial toward the east and marine along the western edge. Evi- 
dence of this shore action is shown in the series of terraces which rep- 
resent ancient sea beaches. They are w'ell exposed on the Oregon coast 
about Port Orford where they rise in three steps, from the coastal 
plain to the level of the Klamath peneplain. The marine deposits of the 
Klamath stage are at the same horizon as the Empire beds whose age 
establishes the age of the peneplain as late Miocene. 
Stage 2.- -This period of erosion was followed by a dislocation of 
the Miocene deposits resulting from the erosion of the Klamath pene- 
plain. The uplift caused little disturbance in the Klamath region but the 
force compressed and faulted the Miocene beds, giving them a north- 
easterly dip. 
Stage 3. — After the elevation erosion began in the Miocene sediments 
and continued in the Klamath peneplain. As a result of the degradation 
of the Miocene beds, the Bellspring peneplain was formed. It cannot 
always be distinguished from the Klamath but the remnants remaining 
are sunfhcient to .estalilish its existence. In origin it is similar to the 
Klamath peneplain l)ut erosion lias reached a more advanced stage be- 
cause of the softness of the Miocene rocks. 
Stage 4. — The Post Bellspring uplift affected all this region both in 
Oregon and in California. The amount of elevation was five hundred 
feet along the coast with increase to two thousand feet at the crest of 
the range. It brought about a working of the Klamath and Bellspring 
peneplains and it is to these disturbances that their irregularities are 
due. 
Stage 5. — As a result of this uplift the formation of the Sherwood 
peneplain was begun. Its greatest extent is about the south fork of Eel 
river and about Sherwood where it is five hundred feet lower than the 
