DENVER & RIO GRANDE WESTERN ROUTE. 227 



region is known as the Great Basin, a land of desert basins and of 

 barren mountain ranges, which in general trend north and south. 

 The precipitation here is slight, ranging in this latitude from 5 to 8 

 inches, and that which falls finds its way into some deep basin in the 

 interior like Great Salt Lake, where the water, when it evaporates, 

 leaves the mineral matter that is carried in solution to form beds of 

 salt or soda. 



The walls of the canyon, although steep, are generally smooth 

 and are covered, except in the higher parts, by brush and dwarf trees 

 of many kinds. In summer they are clothed in a soft, beautiful 

 green, with here and there an evergreen tree to accentuate the soft- 

 ness of the foliage of the other trees, but in September, after the 

 frost has touched the dwarf maples of the higher slopes, the color- 

 ing is magnificent. Many of the slopes are a blaze of scarlet from 

 top to bottom, and others show scarlet interspersed with brown and 

 green. The clumps of aspen give the landscape a touch of gold, and 

 the whole scene presents an unexcelled splendor of autiunn colors. 



The canyon grows broader to the west, and the railroad is built 

 along its north wall. On the opposite side, near milepost 687, is the 

 headgate where the water of Spanish Fork, including that from 

 Strawberry River, is diverted into a large canal, which is soon lost 

 to view as it follows the south wall of the canyon to the mouth and 

 there turns to the left to the area where its waters are most needed. 



The outlet of the canyon is not like the outlets of most of the can- 

 yons that the traveler has seen but seems to be dammed or choked by 

 a great mass of gravel. Where first seen, a little below the intake 

 of the canal, the gravel is at railroad level, and its top is flat, as if 

 it had been washed down the canyon and deposited as a delta in stand- 

 ing water. An examination of the opposite slope shows a terrace of 

 similar material about 100 feet higher. This t-errace also appears 

 to have had a similar history, except that as it is the older of the two 

 deposits most of its gravel was washed away when the second ter- 

 race was formed, and so only fragments remain where they have been 

 protected on the side slopes. These terraces are of the greatest sig- 

 nificance in the interpretation of the late geologic history of this 

 region ; to the geologist they have much the same value that the cliff 

 dwellings or tables of cuneiform writing have to the archeologist. 

 They constitute the record of one of the most remarkable geologic 

 events in this country — ^the flooding of the basin of Great Salt Lake 

 during the ice age to a depth of more than a thousand feet. When 

 these terraces in the Spanish Fork canyon were formed the water 

 of Lake Bonneville, as it has been called to distinguish it from the 

 present lake, entered the mouth of the canyon at the level of the 

 highest terrace, and if a traveler had then attempted to make a west- 

 ward journey here he would have been confronted by an inland fresh- 



