ISOSEISMALS: DISTRIBUTION OF APPARENT INTENSITY. 171 
begins to die out and upon reaching the sandstone ridge turns about the edge of the 
ridge and continues about 100 feet more in the shape of irregular cracks along the ridge. 
The rocks about this crack are probably all Franciscan. The sandstone extends for 
some distance in all directions and is usually shown only by fragments. Cherts, ser- 
pentines, and schists occur a short distance above and seem to be closely associated with 
the sandstones. The strike seems to be northwest and the dip quite steep to the north- 
east. No evidence of faulting was found, but the few outcrops showed little structure. 
The hills for a considerable distance on all sides of this crack are covered with old slides. 
Careful examination and enquiry revealed no extension of the crack in either direction. 
The extension should pass fairly close to the road from Covelo, but none of the 
ranchers along the road knew of any cracks in the hills until Dobbins’ place was reached, 
10 miles southwest, on section 14, township 23 N., range 13 W. Here a crack 600 feet 
long, trending N. 25° W., occurs on a bench 150 feet wide, made up of soft alluvium 
gravel, etc., bounded on the northeast by a steep hill of serpentine; on the southwest by 
a steep slope to the creek 200 feet below, and on the northwest and southeast by bedrock 
ridges. The crack occurs near the outer edge of the bench and the creek (southwest) 
side is a few inches higher than the hill side. It does not continue into the hard rocks 
at eitherend. Between the creek and the hill the ground is soft, miry, and full of springs, 
while at the edge of the hill irregular cracks are sometimes seen, showing that the muddy 
flat had likewise settled relative to the hill and indicating that the soft central area had 
settled relative to the hard, dry slope toward the creek and the bedrock of the hill. The 
crack runs under the cabin where there was the greatest movement, but tho the cabin 
is on four pegs, it was not disturbed. 
In the absence of a map it may be stated that this crack lines up very well with the 
one mentioned above and that the upthrow (?) is on the southeast in both cases. Both 
are in soft material and both are parallel to the streams. Moreover, the road and a ma- 
jority of the ranch houses are roughly in this line, and cracks off this line would be more 
likely to escape detection. No cracks were found between Dobbins and Covelo. Several 
cracks were reported crossing the road from Covelo to Laytonville near the top of the hill 
to the north of Middle Eel River. They are said to continue at irregular intervals for 
a mile or more to the north or slightly north of west. They generally trend north to 
northwest, but vary considerably. 
One mile farther west toward the Eel River, a crack crost the road toward the north. 
There is a strip of soft sandstones and shales thru here resembling that found at the 
Horse Ranch and striking to the northwest. In this strip numerous cracks were found, 
often trending northwest but varying considerably. Four of these cracks were visible, 
but others could not be found as the rains had healed them. It was said that the down- 
hill or southwest side was sometimes higher than the northeast side. Only one of these 
cracks could be ascribed to a slide. The other three might very well have been due to 
the shock. Just north of W. Geforth’s house is a crack 1,000 feet long, trending N. 55° E., 
and following roughly a low ridge running out from the main hills. It cuts almost at 
right angles to the main hills and is in soft material which has little slope. It could hardly 
be an ordinary slide. 
On the top of the ridge, where the soft streak crosses the hills at an elevation of about 
1,000 feet above the river, is a crack about 50 feet long just below a low sandstone knob, 
trending northwest partly across the draw at a considerable angle with the crest of the 
hills. It is irregular and shows no displacement of any kind. It could hardly be a slide. 
Still farther north, just beyond E. Gevire’s house and about 5 miles from Robbins, is 
another crack trending northeast. It is probably a slide. Mr. Gevire stated that there 
were several slides in the hills on all sides of his house, but no other cracks were reported 
to the north. To the south the cracks extended to the river, but none were known south 
of the river, 
