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to the Pacific coast rivers within which to do the same work, 
and which run through cafions of hard Granite or Trap hundreds 
of miles long? The Colorado of the South is 300 miles long, 
and its cafion 8000 to 6000 feet deep! , But as we find on all 
these rivers innumerable side cafions in which no water flows, 
and in fact as we find the whole of this country, which isa sterile 
waste consisting of an almost level sheet of hard lava cracked 
and fissured in all directions, is it not more reasonable to sup- 
pose that all of these cracks, fissures and cafions, have been 
formed by voleanic agency? That when the volcanic cones were 
thrust upwards through and carrying with them the mountain 
chains, that the superincumbent rock, whatever it might be, 
would be bent, distorted and cracked, until “cafions” and 
“passes” would be formed, through which, of course, as 
openings, the streams which were the outpourings of the 
great inland seas, would naturally find their way. Besides if 
the cafions had been formed entirely by aqueous action, it 
seems to me that the Trap would have been worn away so 
gradually, that they would be much wider than we find them | 
and the Trap strata would be worn in a sloping direction 
towards the bed of the stream, whilst the Diatomaceous 
strata, being comparatively soft, would be worn perpen- 
dicularly, or even excavated from under the Trap. Exactly 
the opposite is the case; the Trap invariably presents per- 
pendicular walls whilst the Diatomaceous strata are worn 
sloping toward the middle of the cajion. 
One more point and I must close this long communication. 
How do I account for the formation of the saline lakes 
which have no outlet? Simply thus. It is well known that 
such a thing as absolutely fresh water does not exist in 
nature. The water of all lakes and, of course, rivers contains 
more or less salts of various kinds derived from the country 
over which they and their feeders have flowed. Now I can 
well understand that if the many millions of gallons of very 
slightly saline water which is enclosed within the basin of 
Lake Superior, were to be concentrated by evaporation and 
condensed into a space equal to many of the small saline 
lakes of the West, that we would have an extremely large 
