168 GUIDEBOOK OF THE WESTERN UNITED STATES, 
If it is a hot day in midsummer when the traveler passes down the 
coulee, he may wonder whether the great flows of basalt are not still 
heating the surface. The plain of the Columbia, 
Eltopia. which he is rapidly approaching, has a reputation for 
Elevation 598 feet. great heat in the summer, but as it does not show a 
Population 252.* 
corresponding high temperature in the other parts of 
the year it seems obvious that the great heat is caused 
by the configuration of the mountains and their effect on the movye- 
ment of the atmospheric currents. 
South of Eltopia (see sheet 24, p. 172) the canyon followed by the 
railway becomes shallower and finally merges with the broad plain of 
Columbia River. The lava underlies the plain but dips more rapidly 
toward the south than the slope of the surface, and at Pasco, as shown 
by drill records, it lies more than 200 feet below river level. This 
plain is composed of soft clay and sand (Ellensburg formation) and 
back from the river, where irrigation is impossible, it is nothing but 
a sagebrush desert. In places the regular surface of the plain is 
interrupted by low dunes of sand which have drifted up the slope from 
the channel of the Columbia. The traveler may wonder what can 
subsist in so desolate a land if he has not yet learned that in many 
places water can be procured by digging and that the soil stores up 
enough moisture to raise fair crops when properly cultivated. The 
climate of the region is semiarid, the precipitation being from 6 to 12 
inches a year. The temperature ranges from a minimum of 10° below 
zero in winter to 110° above zero in summer. 
Pasco is a division terminal of the railway and the center of a large 
irrigated district lying above the town and on the east side of theriver. 
The shade trees and green lawns of the town are in 
‘striking contrast to the brown sagebrush of the sur- 
rounding country. 
Immediately after leaving the station at Pasco the 
train is upon the great bridge that spans the swirling 
waters of the Columbia,‘ one of the great rivers of the continent—a 
St. Paul 1,634 miles. 
Pasco. 
Elevation 389 feet. 
Population 2,083. 
St. Paul 1,651 miles, 
‘One of the most interesting parts of 
the history of the exploration of the north- 
western part of the United States is the 
story of the discovery of the mouth of the 
Columbia, or rather of the failure to find 
it by the many navigators who sailed up 
the western shore for the very purpose of 
discov 
ery. 
In 1788 an English captain discovered 
and named Cape Disappointment, just 
_to the north of the river’s mouth, without 
_ recognizing in the inlet to the south the 
mouth of the greatest river on the coast, 
In 1789 two Boston trading ships, the 
Washington and the Columbia, under the 
command of Capt. Robert Gray, visited 
the coast fora cargoof furs. Gray thought 
he saw indications of the mouth of a large 
river in latitude 46° 10’ but did not stop 
to investigate, and after completing a 
voyage around the world his vessel, the 
Columbia, was again dispatched to the 
Pacific coast in 1791. He spent the win- 
terat Nootka Sound, on Vancouver Island, 
and in the spring cruised south from the 
Strait of Fuca in search of the river 
which he thought he saw three years 
before. On his way he met the English 
