diller.] TOPOGRAPHIC DP:VELOPMENT OF KLAMATH MOUNTAINS. 49 
OROGEXK MOVEMENT INITIATING OARBERVILLE STAGE. 
The Sherwood stage was short as compared with the Bellspring and 
Klamath stages, and was brought to a close by an upheaval which 
affected the whole Klamath Mountain and Coast Range region. Al- 
though of wide extent, the uplift was not great, scarcely 500 feet. 
The streams were rejuvenated and a new cycle of erosion was initi- 
ated in flic Garberville stage, which was sufficiently long to enable 
the streams to carve out broad valleys, especially on soft beds. The 
stream most favorably situated for widening its valley during the 
Garberville stage was the South Fork of Eel River. Across the Sher- 
wood peneplain, which was well developed in that region, the South 
Fork cuts a broad valley nearly 500 feet deep, which is sharply distin- 
tinguished from the narrow canyon-like valley of the present river. 
During the Sherw r ood and Garberville stages the rivers developed 
broad valleys, which are in strong contrast with the canyons in which 
the same rivers now flow, and, to facilitate the consideration of the 
broader river valleys which are above and older than the canyons, 
they are grouped together under the general designation "Earlier 
valleys," while the canyons are the "Later A^alleys." 
EARLIER VALLEYS. 
The lines of drainage during the development of the Klamath and 
Bellspring peneplains, the changes introduced by the subsequent 
Fig. 7.— Section showing relation of earlier valleys to Klamath peneplain and later valleys. 
uplifts, as well as the progressive changes in adjustment as the topo- 
graphic cycles advanced after each change of level, furnish a most 
inviting field for investigation, but these can not be satisfactorily 
worked out and described without much more detailed topographic 
surveys. 
The term "earlier valleys" is used to embrace especially those cor- 
responding to the Sherwood and Garberville stages. They gener- 
ally form a marked feature of the upland, but the valleys of these 
two stages can rarely be clearly distinguished. The general relations 
Bull. 190—02 1 
