£24 Dr Fleming on the Geological Deluge , 
last circumstance, which is far from uncommon, marks a third 
epoch in the history of valleys and gravel. In the first period, the 
gravel was transported across continuous plains. In the second, 
valleys were scooped out. In the third, the bottom of these val- 
leys received deposits of gravels. These facts intimate successive 
operations, executed under different circumstances, and seem fit- 
ted for leading to the inference, that some time intervened between 
the several changes. They certainly do not support the conclu- 
sion, that the three phenomena had their origin in the same sudden 
and transient inundation. Under all the circumstances of the 
case, the young geologist will feel himself without a guide, and 
without a test, in determining the sera of the formation of a bed 
of gravel. 1. It may be antediluvian, produced by the bursting 
of a, lake (for lakes must have been numerous, indeed, and ex- 
tensive, before the excavation of so many gorges and valleys by 
diluvial action), spreading its wreck on nearly continuous plains. 
£. It may be the result of the first rush of the diluvian waters, 
previous to the formation of the valleys of denudation. 8. It 
may be the wreck of these valleys, produced during the tumult 
of the retiring waters. 4. It may be the result of the very last 
effort of the flood, to fill up the frightful excavations it had pro- 
duced in the fury of its retreat. 5, It may be postdiluvian, and 
the result of the bursting of an alpine lake : and this gravel may 
have been deposited at very distant intervals. On the banks of 
Glenmornaalbin, diluvium may occur, referable to four different 
burstings of the Lochaber lakes, and all of them prior to human 
record. The diluvium of Martigny, from the bursting of a lake, 
was formed in 1818. When all these probabilities are taken 
into consideration, few, who generalize with ordinary caution, 
will feel inclined to refer to one sera the formation of all our ir- 
regular beds of clay and gravel. 
Independent of the depositions of confused portions of gravel 
and loam, there are likewise extensive depositions of sand, and 
gravel, and clay, of the same materials as the so-called dilu- 
vium ; but which, by being divided into beds and strata, indi- 
cate a subsidence from water in a state of comparative stillness. 
The characters of these beds seem to have been in a great mea- 
sure overlooked by the advocates of the diluvian hypothesis* 
It is not probable that such beds could have been produced by 
