228 



GUIDEBOOK OF THE WESTERN UNITED STATES. 



water sea that extended from the 

 line of the State.»« (See % 60.) 

 Some of the most prominent of 



20 «1 60 ao MILES 



Figure 60. — Map of Lake Bonneville (the 

 indicated by diagonal shading). 



lower plain, which represents a 

 waters. This plain is extensive, 



Wasatch Mountains to the west 



these old shore lines have been 

 named. The highest, the 

 one visible as a terrace 

 about 100 feet above the 

 track, is called the Bonne- 

 \alle shore line. The one 

 at railroad level, which has 

 not been named, represents 

 a later stage of water, 

 when the northern outlet 

 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 of 

 rock, which the outflowing 

 waters encountered when 

 thej' had partlj' cut the 

 barrier that held them in 

 place, and this hard bed 

 held the stream so long 

 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 



the railroad cuts deeper 



and deeper into the delta, 



^^^^ and finally, near milepost 



689, it comes out on a still 



later and lower stand of the 



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 will doubtless convince him that 

 at some time long ago the drainage 

 basin 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. 

 B. L. E. Bonneville, who in 1832 to 

 1S3G explored much of the region for- 

 merly occupied by its waters. 



The late G. K. Gilbert, who was rec- 

 ognized as the leading authority on the 

 history of Lake Bonneville, st\id, in 

 speaking of the highest shore line 

 (U. S. Geol. Survey Mon. 1, pp. 94-99, 

 1890) : 



" If the Bonneville shore line were 

 far less deeply engraved than it is it 



