ISOSEISMALS: DISTRIBUTION OF APPARENT INTENSITY. 191 
300 and 400 feet in height. These are evidently old slides, and the amount of material 
brought down by the recent earthquake, though large, is insignificant compared with the 
size of the scar. At Rools Landing the beach was abandoned, and the wagon road was 
followed to Davis Mill at the mouth of the Russian River. The earthquake here had 
caused several thousand dollars’ damage to trestles on the logging railroads. No buildings 
were moved on their foundations, only chimneys being thrown down. 
From this point the road along the bench above the sea was followed 12 miles to Bodega 
Bay (see map No. 4). The country is sparsely settled. Only three or four houses were 
past, and these were uninjured except for broken chimneys. Near Bodega Head the bridge 
over Salmon Creek was somewhat twisted. Just beyond this a good-sized hotel, previously 
used as a summer resort, was badly wrecked by the earthquake. It was moved on its 
foundations, and rendered unfit for habitation. This building was close to the sand-dunes 
and probably rested on sandy deposits. The barn was completely wrecked. A few hun- 
dred yards beyond this a small mud-flat extends from the sea up to the road. Curious 
mounds of mud, shaped like truncated cones, were thrown up by the earthquake. Subse- 
quent examination showed that the line of the earthquake fissure must have past near this 
spot. 
Duncan’s Mills (J. Parmeter). — On the Russian River, when fisherman tried to seine 
fish after the earthquake of April 18, their nets were torn to pieces by snags, ete., where 
there had formerly been no obstruction. Large trees that had been buried in the bed of 
the river were lifted up by the convulsion, while other trees vanished that had been in 
sight. Low places in the river bed were made high and vice versa. 
The bottom of the river appears to have dropt 2 feet all along by Duncan’s Mills for 
2 miles; and at the mouth of the river, where there used to be water 12 or 14 feet deep, 
there is now only 2 feet, and a riffle till boats can hardly cross, for a length of almost a 
mile. For over a mile there is now a strong current, where there used to be quiet water 
with very little current. A man who was by the river, near Monte Rio, when the earth- 
quake occurred, told the Parmeters that he saw the muddy bottom of the river rise to the 
surface, and the water ran off over the banks. The bottom was the highest where the 
water had been 8 or 10 feet deep; then it settled back. A road and fence moved 10 feet. 
On the other side of Russian River from Duncan’s Mills, 200 or 250 feet back from the 
stream, the earthquake made many holes thru which black sand and water blew up. 
Such blow-holes were made all along this river. Between the river and the ruined hotel 
at Dunean’s is an irregular crack about 20 feet wide, 80 feet long, and 1.5 to 4 feet deep, 
with a blow-hole 4.5 feet wide and 2 feet deep where coarse river gravel came up. 
(R. 8. Holway.)—One hotel at Dunean’s Mills was completely wrecked and other 
buildings were much damaged. Along the river there were several cracks in the alluvium. 
(I. EK. Thayer.) —The shake was of great severity on the Russian River at Duncan’s 
Mills, and totally destroyed a large hotel. Several small houses were thrown from their 
foundations. 
TOMALES BAY TO BOLINAS BAY. 
By G. K. GILBert. 
The following data upon intensity were gathered, with slight exceptions, between April 
26 and May 12, 1906. In their arrangement the order followed is: (1) The line of the 
fault from south to north; (2) the towns of the Rift belt; (8) the peninsula west of 
the Rift; (4) routes of travel east of the Rift; and (5) distribution. 
Along the Fault. — Mrs. Steele’s farm buildings, near the head of Tomales Lagoon, stood 
in a very narrow fault-sag which was traversed by the fault-trace. At this point the trace 
consists of a group of cracks 10 to 20 feet broad. The barn, resting partly on the ground 
traversed by these cracks, was demolished so that, as I saw it, it lay in ruins. The house, 
standing only a few feet to the east of the fault, was thrown from its underpinning and a 
wing was partly separated from it. 
