DENVER & RIO GRANDE WESTERN ROUTE. 
traveler may get his 
-229 
first general view of the Great Salt 
Lake basin. Originally this plain was only a desert, but now it is 
avis still be conspicuous. by reason 
its position. As it is, no geologic 
Bae is necessary to discover it, for 
It confronts all. be- 
insists on recognition. 
The tourist dis visits Ogden and Salt 
City by il on the 
islands a — 
note of rides... The farmer 
who a nt sri eiriies is familiar 
with it and knows that it was made 
by water; and even the cowboy, find- 
ing an easy trail along its terrace as 
he ‘rides the range,’ relieves the mo- 
by hazarding a 
ri 
Gilbert followed this shore line, 
studied it in detail, and mapped it 
throughout most of its sinuous course. 
h copied from his report (see 
fig. 60) shows the greatest éxtent of 
Lake Bonneyille as tli ed with the 
ot Great Salt. L 
istory of pie Bonnevie oe 
back of a time before man s know 
on the globe, or possibly sho to “aa 
time of his first appearance, but in 
any event the conditions ie led to 
man’s activities and hence must have 
been the result of climatic change. 
Gilbert ee = Geol, Survey Bull. 612, 
pp. 96-97, 1915) gives the saaeudisie of 
hake ‘od nto as follows 
“The latest of 
the see into 
which geologists divide past time wit- 
nessed a series of climatic changes 
Which affected the whole earth, and 
* * * the element. which recorded 
its changes most clearly, was tempera- 
ture. There were several epochs of 
cold, and they were separa ated by 
epochs of wa During the cold 
epochs the high axis of the Wasatch 
truded so far beyond the siacheote of 
80697 °—22__16 
the mountain canyons that they 
the lake was largest it was comparable 
in area and depth with Lake Michi- 
gan; it had eleven times its present 
extent. In attaining this great ex- 
panse the water surface rose to a 
sition more than 1,000 feet above its 
present level. - 
“To this great body of water geolo- 
gists apply a distinctive name—lLa 
Bonneville—and they have given much 
istic to its history, which is writ- 
en in shore lines, deltas, channels, de- 
scone and fossils. The shore lines [PIls. 
LXXXIX, A, and XOCVI, B]. appeal 
most to the traveler and may be 
Where it is eroded the limit of erosion 
is marked by a cliff, and bel the 
water is a fot of gentle slope. 
Where additions are made they take 
the form of beaches or bars, which rise 
little above the water level and are 
composed of sand or gravel. At some 
places a bar spans a bay from side to 
side; elsewhere it is incomplete, pro- 
decting from a headland as a spit. 
sont — of Lake paren were 
las those of Lake igan 
pete be the shore into an an. 
rate system of cliffs, beaches, and spits, 
and when the waters finally fell to the 
s 
