88 REPORT OF THE CALIFORNIA EARTHQUAKE COMMISSION. 
REPORT ON A BIOLOGICAL RECONNAISSANCE OF BODEGA BAY REGION. 
By WIuu1AM E. RITTER. 
Accompanied by Mr. E. L. Michael, I examined the Bodega Bay region on October 26-30, 
for evidences of a faunal modification resulting from the earthquake of April 18, 1906. 
My first effort was to secure information from residents of the district bearing on the 
question. A number of families living on the shores of Bodega Bay have their dwellings 
close to the water’s edge. Since the bay is small, closely land-lockt, and hence especially 
free from surf, and since these families spend much time on the water with their small boats, 
which they beach on the gradually shelving shores or tie to their little private piers, it 
seemed that their testimony would be peculiarly reliable. It appeared that any appreciable 
change of level of the water along the shore or any noticeable effects on the shore life would 
hardly escape detection. I talked with five persons of this sort, each by himself. All were 
unequivocal in affirming that neither the level of the water nor the animal life of the bay 
were in any wise altered by the earthquake. 
The earthquake fault at the only point at which it has been located here, passes thru the 
sand-dunes at the head of the bay; and from its general course and the place where next 
observed to the south, must have past nearly parallel with the eastern shore of the bay and 
either have followed the shore or have been to the landward of the shore. In other words, 
nearly if not the whole of the bay, together with the peninsula of which Bodega Head is a 
part, is on the west or seaward side of the fault. All the facts we were able to gather by 
direct observation pertain to the rocky shore of the bay side of the peninsula. Since the 
rock here is a firm granite, and since in some localities the walls are nearly perpendicular, 
are even-faced, and are washt by the waters thruout the day excepting at extreme low tide, 
they are very favorable for furnishing testimony of the kind sought. The question to 
be answered was: Do the organisms that live immovably fixt to the rocks show evidence of 
having either extended or withdrawn the upper limit of their vertical distribution within 
recent time? The organisms that would be available as testimony would be those that are 
most perrhanent in structure, and extend up to the very limit of the high tide. Of first 
importance are the barnacles, two species, Balanus balanoides and Chthamalus stellatus. 
A species of Mytilus, and perhaps one or two species of marine alge, are also more or less 
available. Our attention was given to the barnacles chiefly, but somewhat to the mussels 
also. Neither of us was sufficiently familiar with the alge to make much use of them. 
We could get no evidence that any of these organisms had either extended or with- 
drawn their limits of distribution. In the absence of accurate knowledge on the rate with 
which barnacles develop, there might be some uncertainty as to whether the limits had been 
extended; since, however, the individuals at the upper limit were not found to be in general 
smaller than those farther down; and further, and still more importantly, since the remains 
of dead individuals were quite as numerous proportionally in the upper zone of distribution 
as in the lower, we could but conclude that there was an absence of evidence of extension. 
In other words, there was no evidence of subsidence of the shore. 
As to the question of whether the shore has been elevated at this point, the evidence 
I think is more positive. \ Not only is there lack of proof that elevation has occurred, but 
there is ample proof that it has not. This is furnished by the barnacles chiefly. On the 
vertical granite walls above mentioned, these organisms almost completely cover the sur- 
face up to about 7 feet above mean low water. As already stated, the remains of dead 
individuals are uniformly distributed thruout the area; or, to speak more accurately, 
they are not more numerous proportionally in the upper limit of distribution than in any 
other portion, as would surely be the case had the upper limit been lifted above the former 
high-water mark. It should have been pointed out that the 7 feet to which the barnacles 
extend must be very near, if not quite the limit, of high tide. 
The character of the remains of dead animals is such as to preclude, I believe, being 
misled by the facts. In addition to the heavy calcareous wall which characterizes the super- 
structure of the animal, there is a well-defined continuous platform closely fused to the sub- 
stratum to which the animal adheres. After death the superstructure of the shell falls 
away, leaving the platform as a smooth, hard, calcareous scab clinging to the rock. This 
is very durable, as one can see by observing old piles that have been taken from the water 
and to which these barnacle remains cling. Had any appreciable elevation of this shore 
occurred, there would surely be a zone of dead barnacle shells at the upper range of the 
distribution. The testimony of the mussels, so far as it goes, is confirmatory of that fur- 
nished by the barnacles. 
