THE NORTHERN PACIFIC ROUTE. 191 
broad valley in which the timber has been cleared away and farms 
established. To one not accustomed to the thick forests of the 
Pacific slope, it is a relief to emerge from their dense shade and 
enter open country. 
After crossing Green River and the broad valley in which it flows 
the train passes under a high bluff of gravel (Orting) on the south. 
The origin and geologic age of this gravel, as well as 
of the other formations of the drift in Washington, 
are discussed below by W. C. Alden.‘ This gravel 
has been extensively used by the railway for bal- 
asting the track. At Auburn the railway line 
across the mountains unites with the line from Portland to Seattle. 
The rest of the route is directly north down the valley to its junction 
with Black River, which is the natural outlet of Lake Washington. 
Auburn. 
Elevation 100 feet. 
Population 957. 
St. Paul 1,883 miles. 
least 5 or 6 feet across. At present palms 
do not grow wild within a thousand miles 
of the Puget Sound region 
The traveler will dcabilets be struck by 
the abundance of beautiful ferns now 
growing along the forest borders in the 
open, partly shaded locations. Ferns 
were also present during Puget time, 
though none that have been found are 
very closely related to the living forms. 
= bushy — (Equisetum) are 
places, and the 
ersity. They included 
figs of several kinds, hackberries, mul- 
berries, many willows, alders, birches, 
and oaks, a number of poplars, two spe- 
cies of pepper tree, elms, ashes, maples, 
magnolias, cinnamons, laurels, plums, 
service berries, dogwoods, custard apples, 
chestnuts, crab apples, 
roses, and others nies are without well- 
kacwn vernacular n 
The Sound ec ae hington, at 
the time of deposition of the lower beds of 
the Puget group, is supposed, on account 
of the abundance of ferns, gigantic palms, 
figs, and a number of forms now found in 
the West Indies and tropical South Amer- 
~~“ ica, to have enjoyed a much warmer cli- 
mate than it does to-day; but the pres- 
ence of sumachs, chestnuts, birches, 
maples, dogwoods, sycamore, etc., in the 
upper beds of the group would seem to 
indicate an approach to the climatic con- 
ditions prevailing at present. 
A number of fossil plants have been 
found to be common to the east and west 
sides of the Cascades. This would indi- 
cate that approximately similar condi- 
tions of climate and topography prevailed 
throughout this general area during the 
Puget epoch. The Cascade Range, as it 
now exists, did not then intervene 
1 At a time which probably corresponds 
to the last or Wisconsin stage of glaciation 
in the eastern part of the United States, 
the mountains of Washington were largely 
covered with ice, and the Vashon lobe of 
the Cordilleran ice sheet extended south- 
The ice filled the depressions 
composing the Sound, from the foot of 
the Olympic Mountains on the west to 
the base of the Cascades on the east. On 
the south it reached and covered much 
of the plains south of Olympia. The ice 
of this glacier probably coalesced on the 
the slopes and valleys of the Cascades. 
The melting of these glaciers left depos- 
its of clay, sand, gravel, and bowlders 
betw around 
gah ae which were not thick enough 
