GEOLOGY AND PALEONTOLOGY. 183 
place where rock salt can be obtained on the surface in all the plains country. 
This salt was known and used by the Indians, and was an article of trade from 
the Gulf to the British line, and this locality was a well-known geographical 
point, from which distances were reckoned.’’® The presence of a dozen or more 
trails, now nearly obsolete, radiating from the plain like spokes of a wheel, bears 
testimony to the fact that this place was long used as a source of supply of salt 
to the various forts and settlements of the surrounding regions. Indeed, it is 
but a few years since salt from this plain was hauled for hundreds of miles in all 
directions, and not until the time of the discovery of extensive beds in central 
Kansas did this industry wane. 
The Big Salt plain proper extends for eight miles or more along the Cimarron 
river. In width it varies from half a mile to two miles. On the south bank the 
bluffs of red shale and sandstone capped with gypsum rise directly from the edge 
of the plain to the height of 100 feet or more. North of the plain these bluffs 
are not so steep, and are at a distance of a half mile or more from the plain. 
Even here, however, the sinuous white line of gypsum may be traced along the 
tops of the bluffs as far as the eye can reach. In other words, the plain lies in 
the broad canon of the Cimarron, enclosed on both sides by gypsum-capped 
bluffs of red shale. 
The plain is flat and as level as a floor, except for a few meandering channels 
which, in wet weather, contain a small stream, butare ordinarily dry, Afterarain 
it will sometimes happen that a stream of considerable volume flows over the plain, 
but during the summer months nearly all the water either evaporates or sinks 
into the sand. In places where a small stream still runs down the channel, the 
water is often so salty that a thin crust of crystal white salt forms on the sur- 
face, resembling nothing so much as a sheet of ice across a small stream in 
winter. The entire plain is covered with a thin incrustation of snow-white salt 
crystals. In most places this incrustation is not to exceed an eighth of an inch 
thick, but it reflects the sunlight and blinds the eye likea snow field. Especially 
if the wind be blowing the small particles of salt, a walk across the plain makes 
the eyes smart and burn in a manner not easily forgotten. 
In a large cove on the south side of the plains proper, there are a number of 
salt springs which boil up out of the flat surface of the plain. The water is 
crystal clear, and it sometimes requires more than ocular proof to convince one that 
it contains nearly fifty per cent. of salt. There are scores, perhaps hundreds, of 
these springs on an area a few acres in extent. Some of them flow streams as large 
as aman’sarm; others are much weaker. Inall cases their presence is marked by 
a conspicuous white incrustation of salt, which forms around the spring and 
along the sides of the little stream that flows from it. Particles of grass or 
weeds blown into these springs or streams soon become covered with white salt 
crystals. These strings of crystals are often an inch or more in diameter and look 
like rock candy. In places the incrustations around the springs are so thick 
that the salt may be scraped up and hauled away. This is the source of the so- 
called rock salt of the plain. 
The Little Salt plain is located a few miles further up the Cimarron, just on 
the border of Kansas. It does not differ materially from the plain just described, 
except that it is much smaller and the bluffs on either side of the river are 
neither so high nor precipitous. 
Besides the two plains of the Cimarron, the Salt Creek plain, in northern 
Blaine county, also belongs to the Salt Plain formation. Like the others, it is 
located in a cafion at the foot of the Gypsum hills. This plain is much smaller 
6. Kans, Hist. Coll., vol. V, 1896, p. 89. 
