Correspondence. 353 
formation is eliminated by its constant association with the Cave Creek 
gypsum formation, and finally because (as stated in "The Permian Sys- 
tem in Kansas") the red shales of the Dog Creek agree better in litho- 
logical character and color with those of the Salt Fork division below 
the Cave Creek than with chose which are most characteristic of the 
Kiger division, and often contain, in their lowest part, seams of gypsum 
similar to those in the horizon next below the Medicine Lodge gypsum, 
(viz., the Flower-pot horizon of the Glass Mountain formation), I am 
now led to transfer the Dog Creek formation from the Kiger to the 
Salt Fork division, placing the line between the two divisions where, in 
preparing my earlier paper above cited, I suspected that it should be 
drawn, viz., at the summit of the Dog Creek formation. Thus we have 
in the Salt Fork, or lower division of the Cimarron series, three cycles 
of precipitation: the first of salt, the second of gypsum, and the third 
of dolomite, each including two stages, a preparatory and a culminating 
stage: the preparatory represented in each instance by a greater, and 
the culminating Vjy a lens thickness of j'ocA;, but the former stage by 
less and the latter by greater bodies of the precipitate. This relation 
may be graphically indicated in the following table, which expresses the 
genetic relations of the salt fokk division. 
Culminating stage -' 
Preparatory stage -] 
Culminating stage -J 
Preparatory stage -j 
Culminating stage -J 
\ 
] 
Preparatory stage 
Chapman 
\ 
Dog Creek or Stony Hill 
Amphitheatre 
. 
cycle of precipitation 
of Dolomite. 
Cave Creek 
r 
1 
yEtna 
Glass Motmtain 
I 
cycle of precipitation 
of Gypsum. 
Salt Plain 
r 
1 
Kingfisher 
Harper 
■{ 
cycle of precipitation 
1 
1 
of Salt. 
In this table the Cedar Hills sandstone is omitted as probably of only 
local development. ^Etna, from ^Etna, Kansas, is here proposed for 
the first time as a common name for the Glass Mountain and Cave 
Creek formations, expressing the genetic and chemical relationship be- 
tween them. The names Glass Mountain, Amphitheatre and Chapman 
are explained farther on. 
The so-called great salt spring at the head of Salt creek is the source 
of a large amount of strong brine. It is not in the form of a single bold 
spring, as might be inferred from its name. The divide between the 
Cimarron and North Canadian rivers, opposite the head of Salt creek, 
consists of Black-jack-wooded Neocene sands, commonly known as 
"Jack-sands," whose thicker ])arts seem to include superficial reolian 
layers and deeper deposits of aqueous origin with basal, water-bearing 
gravels. Above the great salt spring, the eastern border of this wooded 
upland crowns an acclivity of between 300 and 400 feet, the lower 235 of 
which (including the Glass Mountain and Cave Creek formations) forms 
