Ch. XIII. J 
CRAG. 
181 
as one of the ' Needles ', or insulated rocks of chalk, which 
projected 120 feet above high water-mark, at the western 
extremity of the Isle of Wight, fell into the sea in 1772*, 
so a pinnacle of chalk may have been precipitated into the 
tertiary sea, at a point where some strata of the crag had 
previously accumulated. The beds of flint and chalk in the 
above diagram appear nearly horizontal, but they are in fact 
highly inclined inwards towards the cliff". The rapid waste of 
the Norfolk coast might soon enable us to understand the true 
position of this mass, if observations and drawings are made 
from time to time of the appearances which present themselves. 
Perhaps it may be necessary to suppose, that subterranean 
movements were in progress during the deposition of the crag, 
and the extraordinai'y dislocations of the beds, in some places, 
which in others are perfectly regular and horizontal, may be 
most easily accounted for by introducing an alternate rise and 
depression of the bed of the sea, such as we know to be usually 
attendant on a series of subterranean convulsions. Several of 
the contortions may also have been produced by lateral move- 
ments. 
Passage of marine crag into alluvium. — By supposing the 
adjoining lands to have participated in this movement, we may 
explain the origin of those masses of an alluvial character 
which contain the detritus of many rocks, the bones of land 
animals and of drift timber, which were evidently swept down 
into the sea. The land-floods which accompany earthquakes 
are, as we have seen, capable of transporting such materials to 
great distances f, and, as part of these alluviums must be left 
somewhere upon the land, we may expect to find, on exploring 
the interior, a gradual passage from the terrestrial alluvium 
to that which was carried down into the sea, and which alter- 
nates Avith marine beds. 
The fossil quadrupeds imbedded in the crag appear to be 
the same as those of a great part of the alluviums of the interior 
* Dodsley's Annual Register, vol. xv, p. 140. f Vol. i. chap. 25. 
