184 KANSAS ACADEMY OF SCIENCE. 
than the Big Salt plain just described. It is not to exceed a quarter of a mile 
wide in the widest place, and for the greater part of its course is not more than 
100 yards in width. It is perhaps three miles long. 
The region of Salt creek is one of the most picturesque spots in Oklahoma. 
The upland covered with jack-oak-bearing Tertiary sands breaks off into precipi- 
tous cliffs and cafions 200 or more feet deep. The slopes of these cafons are 
composed of the brick-red shales of the Glass Mountain formation, and are 
capped by the massive white ledges of gypsum and dolomite of the Cave Creek 
formation. Dozens of narrow caflons with cedar-covered slopes radiate out- 
ward from Salt creek and its tributary, Bitter creek. It is in the head of the 
main Salt Creek canon that the springs which supply the plain are found. A 
fifteen-foot ledge of red-and-blue-mottled, cross-bedded sandstone outcrops in 
the heads of several branches of the main canon. It is from this saliferous 
sandstone that the springs issue. Along the bottom of the cajion salt incrusta- 
tions cover a narrow strip 100 yards or more in width. A mile below the springs 
the canon widens out and the creek leaves the wall of hills and enters the flat 
country. The salt plain spreads out, and in one place becomes perhaps a quarter 
of a mile wide. A mile or so down the creek it is joined by other streams and 
soon loses its individuality. 
From the standpoint of economic importance the Salt Creek plain exceeds all 
others in the territory at the present time. A number of primitive salt plants 
are located along the edge of the plain. The methods employed in the evapora- 
tion of salt are extremely simple. A well is dug in the soft sand of the plain, and 
the water pumped by hand into vats and evaporated by boiling. It is stated that 
three buckets of brine make one of salt. The capacity of the best plant running 
at the present time is approximately 2000 pounds per day. The salt is hauled in 
wagons to supply local trade. The demand is said to exceed the supply for a part 
of the year. There is enough brine in this locality alone to make a number of 
car-loads of salt a day. 
The largest salt plain in Oklahoma, however, is not near the Gypsum hills, 
nor even in the region of outcrops of the Salt Plain formation. It isin the north- 
eastern part of Woods county. The nearest point of the Gypsum hills is at least 
thirty miles from this plain. Asstated above, the geological horizon is well down 
in the Harper, perhaps 200 feet below the top of this formation. This plain is the 
only one in the territory that is not located on the waters of the Cimarron. It is 
usually known as the Salt Fork plain, from its position on the Salt Fork of the 
Arkansas. The plain occupies an area approximately eight miles north and south 
and six miles east and west. The greater part of the plain lies south of the river. 
It is as level as a floor and absolutely bare of vegetation. Only here and there 
does an occasional bit of driftwood break the dreary monotony. Ona warm day 
a view across the snow-white plain stretching away into the seemingly infinite 
distance will often reveal a mirage shimmering along the horizon. Trees, water- 
courses and cultivated fields stand out in bold relief, and so natural do they ap- 
pear that one may sometimes be tempted to believe that they are more than mere 
optical illusions. 
