112 The Americam Geologist, February, 1903 
This last gypsum deposit is such a promising proposi- 
tion that a mill is expected to be placed on the property and 
in operation within another year. 
It tlius may readily be seen that the commercially pro- 
ductive gypsum deposits lie on the eastern base of the Rocky 
mountains or in other words on the foot-hills of the main 
range. It may also be seen that the deposits are numerous, 
quite thick, and fairly free from impurities. They also have 
a wide range, running across the state from northwest to 
southeast, thus making it possible to compete in every town 
in the state with outside products. 
Geoloi^ica/ Formations 0/ the Gypsum Deposits. 
According to Weed the middle field belongs to the 
lower Carboniferous. The writer collected several good 
fossils from this locality during the past summer and found 
that the gypsum deposits lie directly upon (lower Carboni- 
ferous) limestone. The fossils gathered from the limestone 
are too poor for specific identification, but Dr. T. W. 
Stanton recognized the genera. Trigonia, Pleuromya, 
Cyprina (?) and Natica (?) all from the Jurassic. Farther 
west this dips under the Cretaceous. The beds from all 
paleontological evidence belong undoubtedly to the Car- 
boniferous. 
Not so with the southern beds. According to Darton 
these beds rest immediately u):»on the Triassic inasmuch as 
they rest upon the typical "red beds." There is no paleon- 
tological evidence here that the "red beds" are Triassic, but 
immediately above the gypsum deposits, stratigraphically 
and paleontologically. the formations belong to the Jurassic. 
The fossils found from fifty to seventy-five feet above the 
gypsum deposits in Carbon county show the typical marine 
Jurassic as found in the northwest. Some of these fossils 
were identified by Dr. T. W. Stanton of the National 
Museum and they were Ostrea, sp., Gryphaea calceola var. 
nebrascensis I\r. & H., Belemnites densus M. & H. The 
southern beds are without doubt in the same formation as 
those in Wyoming, and according to Knight, it is believed 
that the gypsum-bearing beds of W^yoming will prove to be 
Perrnian. So until farther paleontological evidence is found 
