20 University of California Publications in Zoology [ Vou. 14 
than this. The maximum width of the bay is rather more than 10 
nautical miles (16 kilometers). 
As regards area, the figures employed in the present report were 
obtained by dissecting Coast and Geodetic Survey Chart No. 5530 
and carefully weighing the amount of paper covered by the bay as a 
whole, as well as by the various regions which it was desired to treat 
separately. The weight of a unit area was determined from that of 
a large rectangle, occupying a given number of degrees of latitude 
and longitude.® Two separate charts were used for these determina- 
tions, and the mean of the two sets of figures were employed. 
Carquinez Strait and Suisun Bay were naturally omitted from the 
area computed, this last being regarded as terminating at a line drawn 
from Mare Island Light to Selby. At its lower end the bay was 
considered as extending to the level of Beacon No. 11, at the mouth of 
““Coyote River.’’ The Golden Gate was included, as far out as a line 
drawn from Point Bonita to Mile Rock, this being the limit recognized 
by the Coast and Geodetic Survey. The areas covered by the various 
islands were, of course, deducted from the total, while salt marshes 
and estuaries were likewise excluded. 
The following figures are the outcome of these determinations. 
The miles here intended are statute miles (1 square mile = 2.59 square 
kilometers ). 
TABLE 1 
1. Total Surface Covered at High Tide 
Square miles Percentage 
San Francisco Bay, in narrow sense .....-......------.- 287.7 71.9 
Sam Pablo anys cc2c:22. cic ecccee reper eee eee 112.3 28.1 
Total area of San Francisco Bay?.................... 400.0 100.0 
2. Areas Covered by Water of Various Depths 
Square miles Percentage 
Area exposed at low tide ....-.------------ccecsereceecscenoee 54.2 13.6 
From last zone to 3-fathom line --.............-....- 226.0 56.5 
Between 3- and 5-fathom lines -............ oe 45.9 11.5 
Meeper) than’ deta toms ecesee eee eee ereren 73.5 18.4 
"Potall: avecs.e.te sesc ops capes er 399.6 100.0 
5 The value in square miles of an area 30’ square, at the mean latitude of 
San Francisco Bay, was found by reference to the Smithsonian Geographical 
Tables. 
6 The figures obtained from the two charts upon which these figures are 
based were 397.4 and 402.7 respectively. A third chart, which was treated 
somewhat less carefully, gave an area of about 397 square miles. 
