228 
GUIDEBOOK OF THE WESTERN UNITED STATES. 
water sea that extended from the Wasatch Mountains to the west 
line of the State.®° (See fig. 60.) 
Some of the most prominent of these old shore lines have been 
14 
= named. The highest, the 
one visible as a_ terrace 
about 100 feet above the 
track, is called the Bonne- 
ville shore line. The one 
l at railroad level, which has 
not been named, represents 
a later stage of water, 
when the northern outlet 
Be 
had been cut down below 
its first position but not so 
low as it became later. It 
probably records the posi- 
tion of a harder bed o 
+ rock, which the outflowing 
‘waters encountered when 
they had partly cut the 
barrier that held them in 
i} place, and this hard bed 
ee % 
Wy 
ersisee 
held the stream so lon 
that it permitted Spanish 
Fork to build at this 
height a delta of consider- 
able extent. 
In its descent to the 
lower level of the valley 
fC) 20 40. 60 _ _—saBO MILES 
FIGURE 60. —Map Lake 
indi ented al diagonal shading 
lower plain, which represents 
waters. 
reer Me area 
and deeper into the delta, 
ne" finally, near milepost 
689, it comes out on a still 
a later and lower stand of the 
This plain is extensive, and from its even surface the 
The Bonneville shore lines and 
broad flats that the traveler has al- 
ready seen at the mouth of Spanish 
Fork canyon and the others that he 
will see before he reaches Salt Lake 
City thay doubtless convince him that 
at Some time long ago the drainage 
rate of which the present Great Salt 
Lake occupies only the deeper part 
was filled with water to the highest 
shore line, or about 1,000 feet. This 
old and vanished lake has been named 
Lake Bonneville, in honor of Capt. 
. L. E. Bonne 832 
The late G. K. Gilbe 
ognized as the leading authority on the 
Bonneville, said, in 
speaking of the highest shore line 
(U. S. Geol. Survey Mon. 1, pp. 94-99, 
890) : 
“If the Bonneville shore line were 
far less deeply engraved than it is it 
ut the railroad cuts deeper. 
