Correspondence. 435 
5. Fourteen feat of red-brown and drab thick-bedded sandstone, containing peb- 
bles. 
6. Sixty-two feet of coarse and pebbly sandstone, yellowish and whitish, the 
lower beds ripple-marked . 
7. Twenty-seven feet of red, sandy shales. 
8. Four feet of yellowish and drab-streaked clay. 
No. 6 contains round sandstone concretions, in size and appearance like 
cannon balls. 
The limestone stratum here may with certainty be referred to the lower 
Cretaceous — Gulf Cretaceous of Hill. 
On the hill west of Colorado City, and about 140 feet above the stream, 
borings have penetrated to 1,116 feet. At 45 feet depth they entered 20 
feet of dark-colored beds containing vegetable remains. Red sandstone 
was penetrated before reacliing 100 feet, and below 130 feet chiefly red 
beds. Red sftnd was reported from 534 to 1,116 feet. Rock salt was passed 
through from 815 to 842 feet; then a few feet of rock, and then 43 feet of 
rock salt. At the bottom of the boring, or 1,116 feet from the fcurface, a 
fine white sand was penetrated, containing pure water, which at first flowed 
out at the surface, and then fell back 134 feet. Just below the lowest salt 
bed there is 10 feet of gypsum ; also seven feet of gypsum at 1,030 feet, and 
10 feet at 1,080 feet. The water rising above the salt becomes saturated and 
is pumped out and evaporated, and salt of great purity is made. The salt 
industry is successfully carried on, although as yet the exportations are 
chiefly confined to Texas. 
Two interesting localities in Mitchell county deserve especial mention, 
where buffaloes have worn paths in the solid rock, showing well-marked 
foot-prints. One of these is on liOne Wolf creek, four miles west of Colo- 
rado City. The path is about a foot wide and nearly ten inches deep ; the 
steps nearly three feet apart, with four inches between the foot-prints. It 
follows the gentle incline of the rock surface in the dry bed of the creek, 
and shows that the animals had passed down to the water to drink, and 
then out on the other prairie beyond, for the tracks all slope one way. The 
forward wall of the track is higher than the rear, and more abrupt. There 
are two paths at this place, which are plainly marked for over 100 feet. 
Another very interesting place is at the forks of the Champion, seven 
miles south from Colorado Citj'. Another plainly marked buffalo trail is 
seen here worn in the solid rock. The slope of the rock is 15° to 25", and the 
steps are two feet from centre to centre ; the foot-tracks eight inches deep, 
14 incites long, and path seven inches wide. This locality is known as the 
Seven Wells on account of a series of well-m irked pot-holes in the sand- 
stone. Tlie two forks of Champion come together here, and just at their 
juncfon is a plunge of over 20 feet into a hole 25 feet wide. The other 
pot-holes are situated just within the forks of the sti*eam, and are of various 
sizes, varying from six to eight and ten feet across, with others of smaller 
size, and are mostly full of water and are over 10 feet deep, and one is re- 
ported to be over 50 feet deep. There is no doubt but some are over 26- 
feet deep, but I did not have the means of measuring their depths. They 
are of greater diameter below than at the top, and are worn very smooth 
upon the sides. All of them contain gravel, and some are nearly filled 
