Notice and Review of the Religuiae Diluvianae. 335 
ful agency. We have seen hard, unstratified, quartzose 
masses, of several tons in weight, torn out of their beds by 
a mountain torrent, and removed a considerable distance. 
But in level countries, and where the stream has no great 
descent, it is found that rivers have not power to move ex- 
cepi in a few extraordinary instances, even small pebbles. 
In very many cases of large rivers, it is found, that so far ' 
from having formed their own beds, they are actually ina 
gradual manner filling them up. We have an instance of 
this in the vallies in which run the Missouri and Mississippi, 
as described in Long’s Expedition, Vol. I. p. 114. The 
author believes that the Missouri excavated its own bed, of 
an average depth of one hundred and fifty feet below the 
immediate banks, and three hundred below the great plains 
at a distance on either hand. Yet he says, “if we admit 
that this great valley with its numerous ramifications, has 
resulted from the operation of currents, wearing down and 
transporting to the ocean the solid materials of the earth’s 
surface, it would appear necessary still further to acknow]l- 
edge that this channel was once much deeper than at pres- 
ent ; for we usually meet with thick alluvial depositions 
covering the rocks that line the bottom of the Missouri vl- 
ley. The manifest tendency of the Mississippi, at this time, 
upon its valley, is to fill up rather than to excavate; but it 
may be doubted whether this is equally, or even to any de- 
gree, the case with the Missouri.” 
Again ; how happens it that the source of a river is fre- 
quently below the head of a valley, if the river excavated 
that valley ? Rivers also sometimes change their beds ; 
but if they excavated their own beds, how could they 
change them? And to suppose that rivers formed their 
own banks, is to suppose they were once without banks. 
The most powerful argument, however, in our opinion, 
against the supposition we are combating, 1s the phenom- 
ena of transverse and longitudinal valleys ; both of which 
could not possibly have been formed by existing streams. 
But we cannot here enter minutely into this subject ; and 
can only refer our readers to the works of Greenough, 
Conybeare, and Phillips, and Kidd, and to a paper of Sir 
James Hall, in the VII. Vol. of the Transactions of the 
Royal Society of Edinburgh, which Mr. Buckland recom- 
mends “‘ to the attention of every one who has the smal- 
