Ch. XI.J 
NEWER PLIOCENE ALLUVIUMS. 
145 
with the same ochreous clay which envelops the osseous remains 
of higher antiquity 
NEWER PLIOCENE ALLUVIUMS. 
Some writers have attempted to introduce into their classi- 
fication of geological periods an alluvial epoch, as if the 
transportation of loose matter from one part of the surface of 
the land to another had been the work of one particular period. 
In our opinion, they might have endeavoured, with equal 
propriety, to institute a volcanic period, or a period of marine 
or fresh-water deposits. We believe, on the contrary, that 
alluvial formations have originated in every age, but more 
particularly during those periods when land has been raised 
above its former level, or depressed below it. We defined 
alluvium to be such transported matter as has been thrown 
down, either by rivers, floods, or other causes, upon land liable 
to inundations, or which is not permanently submerged beneath 
the waters of lakes or seasf. As examples of the other causes 
adverted to in the above definition, we might instance a wave 
of the sea raised by an earthquake, or a water-spout, or a 
glacier. 
We have said permanently submerged in order to distin- 
guish between alluviums and regular subaqueous deposits. 
The latter are accumulated in lakes or great submarine re- 
ceptacles, the former in the channels of rivers and currents, 
where the materials may be regarded as being still in transitu, 
or on their way to a place of rest. There may be cases where 
it is impossible to draw a line of demarcation between these 
two classes of formations, but these exceptions are rare, and 
the division is, upon the whole, convenient and natural, the 
circumstances being very different under which each group 
originates. 
Marine alluvium, — The term ( marine alluvium' is, perhaps, 
admissible if confined to banks of shingle thrown up like the 
* Joura, de Geologie, tome iii. No. x. p. 1G5. 
-j- Vol. ii. chap. xiv. 
Vol. III. L 
