184 GEOLOGICAL ITEMS, 
foundation is exceedingly firm and hard while 
dry, it seems the most soluble of earths, and 
melts almost as rapidly as snow under the 
action of water. The tenacious turf of the 
‘buffalo grass,’ however, retains the marginal 
surface, so that the sides are usually perpen- 
dicular—indeed, often shelving inward at the 
base, and therefore utterly impassable. I have 
come unsuspectingly upon the verge of such 
a chasm; and though, to a stranger, the ap- 
pearance would indicate the very head of the 
ravine, I would sometimes be compelled to 
follow its meandering course for miles with- 
out being able to double its ‘breaks.’ These 
I have more especially observed high on the 
borders of the Canadian. 
The geological constitution of the Prairies 
is exceedingly diversified. Along the eastern 
border, especially towards the north, there 1s 
an abundance of limestone, interspersed with 
sandstone, slate, and many extensive beds of 
bituminous coal. The coal is particularly 
abundant in some of the regions bordering the 
Neosho river; where there are also said to be 
a few singular bituminous or ‘tar springs,’ as 
they are sometimes called by the hunters. 
There are also many other mineral, and pat- 
ticularly sulphur springs, to be met with. 
Further westward, the sandstone prevails; 
but some of the table plains are based upon 
strata of a sort of friable calcareous rock, 
which has been denominated ‘rotten lime- 
one: yet along the borders of the moun- 
tains the base of the plains seems generally 
