534 
BUIvIvETIN oe the bureau oe eisheries. 
All of these valleys are 
occupied by streams. In the 
westernmost valley and in the 
second one to the east from 
thisarefoundtwoof the creeks 
that unite to form the Clyde 
River. In the easternmost 
valley is found one of the 
branches of the Onondaga 
River. Theremainingsixval- 
leys have been much modi- 
fied and deepened by glacial 
action and are filled in part by 
long, narrow, relatively deep 
lakes. These are the Finger 
Lakes, so called from their 
form and because they diverge 
somewhat as do the outspread 
fingers from the hand. The 
seventh lake of this series, 
Keuka Lake, occupies a 
branching valley which seems 
to have drained originally to 
thesouth. It was worked over 
by the ice in a way similar to 
the other lake-filled valleys, 
and now drains by a post gla- 
cial stream into Seneca Lake. 
The valleys occupied by 
these lakes are undoubtedly 
of preglacial origin, but they 
were profoundly altered by 
the invasion of the ice. Sen- 
eca and Cayuga Lakes extend 
below the level of the sea (see 
fig. 2), the deepest parts of the 
Seneca Basin being 53.5 me- 
ters (180 feet) below sea level 
and those of Cayuga 16.4 me- 
ters (54 feet). These figures 
do not represent the maximum 
depth of the valleys. In the 
flat at Watkins, near the south 
