dillek.] OLD V r ALLEYS. 55 
EARLIER VALLEY OF EEL RIVER. 
Eel River is next to the Klamath in size among those in northwest- 
ern California, and the history of its struggles in developing its pres- 
ent valley would form a most interesting chapter, but for the present 
only a few of the features will be noticed. Like Mad River, Eel River 
has its lower course in a thick series of soft sediments deposited along 
the edge of the Klamath peneplain during its development. In the 
case of Eel River, however, remnants of the earlier valley are still 
preserved in the soft beds of the Wildcat series which occur in the 
flat-topped hills on the western slope of Bear Ridge, at an altitude 
of about 1,000 feet. The valley was so filled with smoke during the 
writer's visit that a satisfactory view of its form from Bear Ridge could 
not be obtained. While the 1,000-foot level was Avell marked in 
places with terraces of the soft beds rising even to 2,000 feet, the gen- 
eral distribution of the 1,000-foot level along that part of Eel River 
could not be as completely determined as was desired. The divide 
between Rio Dell and Hydesville bears a well-marked plain cut on 
highly inclined strata, rising about 850 feet above sea level. Near the 
coast the plain descends to 700 feet as a well-marked terrace. This 
is evidently the plain corresponding to the one so well marked on the 
soft beds of Mad River opposite Korbel. 
The valley of Eel River was crossed about 50 miles above its month, 
between Blocksburg and Harris, where the earlier valley is not so 
well marked in contrast with the late one. At this point the river is 
crossed by a bridge in a canyon only a few hundred feel deep. The 
river at the bridge is only about 500 feet above tide, and above a rel- 
atively small canyon the sides of the valle}^ are rather gentle. Far- 
ther upstream they become much steeper, and the valley becomes 
canyonlike to an altitude above the river of approximately a thou- 
sand feet. Along the road leading northwestward, at an altitude of 
1,500 feet an ancient valley level is marked. 
Farther upstream Eel River was crossed twice on the road from Ukiah 
to Laytonville by way of Covelo. At Eden Valley and Round Valley 
on this route there are several local levels of wide extent about 5< M > feet 
apart. Their development may indicate the presence of a large mass 
of soft Miocene rocks, remnants of which have already been noted as 
occurring on Salt Creek and along the western border of Round Val- 
ley. Eel River at the ferry on the Eden Valley road is 725 feet below 
Round Valley and has an elevation of 1,450 feet above sea level. It 
flows in a valley with slopes becoming steeper farther downstream, 
where it is crossed by the road to Laytonville. Near the last cross- 
ing the earlier and later valleys are well marked. The later valley 
has slopes of 41° and is 1,000 feet deep, while above them the slopes 
decline to 11° and the relief features become much less bold. 
On the South Fork of Eel River there is a great development of soft 
Tertiary strata which have been leveled to the Sherwood peneplain. 
