90 REPORT OF THE CALIFORNIA EARTHQUAKE COMMISSION. 
REPORT ON A BIOLOGICAL EXAMINATION OF THE BOLINAS LAGOON REGION, 
NOVEMBER 24-25, 1906. 
By Cuarues A. Kororp. 
Bolinas Lagoon. — The distribution of barnacles along the shore, on the piles, etc., was 
examined with reference to possible changes in level, near Bolinas wharf on the western 
side of the lagoon and on Morse’s wharf on the eastern side, the principal locations on which 
barnacles occur about the bay. In neither case was there evidence or local testimony of 
disturbance in levels of the ground on which the barnacle-bearing substrata were located. 
The possibility of local slumping of soil is not, however, entirely excluded. No barnacles 
on rock in place were observed in the bay. 
There is no evidence from the distribution of barnacles of any change in level of the 
eastern side of the bay. There is neither any marked destruction of old or absence of young 
in the upper levels such as would follow elevation, nor any marked recent occupation of an 
upper belt by young barnacles such as would follow depression. On the western side of the 
bay, on the piles of the warehouses at the landing, there was a faintly defined zone 6 to 8 
inches wide in which the proportion of dead barnacles was unusually large. The percentage 
of dead in the uppermost levels on Morse’s pier on the eastern side of the bay varied from 
2 to 35 per cent with predominant range of 10 to 20 per cent. On the piles on the western 
side at similar levels, the proportion of dead was predominantly 40 to 60 per cent and not 
infrequently ran above these figures. Below this upper belt there was frequently less de- 
struction and a relatively greater number of young than was found in the uppermost levels. 
It may be that this destruction was due to elevation, tho the uppermost belt of barnacles 
is still just submerged at a 5.4-foot tide. It might also be due to the considerable increase 
of silt attendant upon the large amount of talus shaken into the bay and along the adjacent 
shore line by the earthquake. The fact that barnacles attached themselves to and throve 
on buildings thrown into the bay not far from the piles in question, would indicate that 
destruction by silt was confined to the time of the earthquake or that destruction did not 
take place as a result of silt. 
The ‘studio building” at Bolinas, which was thrown into the bay by the earthquake 
and raised some months later, was well covered on submerged portions by barnacles, mainly 
half or two-thirds grown. This fact makes it certain that the young barnacles have been 
attached in large numbers since the earthquake, and that their distribution, therefore, 
affords critical evidence of change in levels. | 
The Sea Coast Line. — The evidence here from the distribution of barnacles is inconclu- 
sive, owing to the great range of movement of water in the breakers and the relative scarcity 
and small size of the barnacles present. There was no evidence of any change of levels, but 
their numbers are probably too small to afford evidence of a movement of a few feet only. 
The Clam Patch. — The evidence of elevation here is entirely in the nature of testimony. 
The barnacles on rock in place in this region are too near the low-tide level to afford a satis- 
factory criterion. A few rocks in place near the upper levels show no trace of extensive 
destruction of barnacles such as might follow an elevation of 1.2 feet which Dr. Southworth 
believes to have taken place. But here again the biological evidence is too incomplete to 
have much weight. There is no doubt that *there were clams in a shallow gravel bed 
resting on rock in place and abundantly exposed at a 2.1-foot tide. 
In my opinion, from the evidence in hand, there was no depression of the eastern margin 
of Bolinas Lagoon as the result of the earthquake of April 18, 1906. Dr. Southworth’s 
testimony, taken in conjunction with the destruction of barnacles in the upper levels on 
the western side of the bay, suggests the possibility of a small elevation on that side. 
