84 REPORT OF THE CALIFORNIA EARTHQUAKE COMMISSION. 
About Tomales Bay. — Professors Kofoid, Torrey, and Holway examined practically 
the whole shore of Tomales Bay, and also visited the outer or ocean side of Tomales 
Point. Their attention was directed especially to the condition of barnacles at the upper 
limit of the zone of marine life, and the evidence they found does not show any change in 
level, either by elevation or subsidence. It is their opinion that the injury to the clam 
industry along the northeastern shore of the bay is referable to other causes, including at 
some points the exceptional inwash of detrital material from the shore, and at others the 
shifting of loose material toward the center of the bay. 
After the discovery of the vertical dislocation in Pepper Island, I visited the Papermill 
delta at the head of Tomales Bay in search of similar evidence of displacement, but failed 
to discover it. There are on the delta several tracts on which water stands after the fall 
of the tide, and the plant growth, especially Salicornia, shows deterioration in these areas ; 
but the areas are not systematically related to the fault-trace. They occur on both 
sides and at least one of them is intersected by the trace. They constitute part of the 
evidence of a gentle, broad undulation of the delta surface, which appears to have been 
occasioned by the earthquake. A tentative theory to account for this undulation is 
that lenticular bodies of soft clay, included in the delta deposit, experienced a certain 
amount of flow during the earthquake period. The lane of water following the fault- 
trace, and described on an earlier page, is an independent phenomenon closely asso- 
ciated with the fault, and the depression causing it does not extend indefinitely toward 
the east. In a general way, the half of the delta east of the fault stands as high as the 
half at the west. On the lower slope of the delta, beyond the region of plant growth, 
there is a tract east of the fault which received the principal deposit of sediment brought 
by the floods of 1907. The localization of this deposit suggests that the transporting 
current may have been guided by a depression of the surface, but if so the depression was 
not bounded on the one side by the fault line; its southwestern boundary is a distributary 
of the creek. As the tract on which this deposit took place is opposite a portion of the tract 
in which mud was shifted toward the southwest shore, it seems possible that the area of 
shifting here included practically the whole width of the bay, and that the resulting ele- 
vation of the bottom toward the west was accompanied by a lowering of the bottom 
toward the east. In that case, the apparent lowering of the clam zone at various points 
on the northeast shore may be correlated with the phenomena near the head of the bay, 
and the whole ascribed to a general shifting of loose material in the bottom of the bay 
toward the west. 
Bodega Bay. — As the title of Bodega Bay is variously applied on different maps, it is 
proper to specify that the body of water here intended is the land-lockt lagoon east of 
Bodega Head, and not the open roadstead farther south. Professor Ritter examined 
this with care, studying especially the distribution of barnacles, and found no evidence of 
absolute or differential change of level. 
Summary. — At Bolinas Lagoon, subsidence occurred east of the fault, its vertical 
amount being approximately a foot. The subsided tract included the greater part of the 
area of the lagoon, and may have had its eastern Jimit along the eastern shore of the 
lagoon. The subsidence was possibly a continuation of the local movement of disloca- 
tion by which the basin containing the lagoon was created. There may have been local 
elevation of a tract extending from Bolinas westward and northwestward. The evidence 
is not demonstrative, but leaves a presumption in favor of such elevation. 
About Tomales Bay and Bodega Head there was probably no appreciable change in 
the general elevation of the land, most facts which tend to show such change being 
explained by assuming that in Tomales Bay there was a general shifting of mud and 
other incoherent material toward the west. Such shifting had been fully demonstrated 
in the vicinity of Inverness. 
