INSULATED FLINTS AND DETACHED MASSES OF CHALK. 245 
summits of the interior, from the ridges that encircle the vales of 
Sidmouth and Honiton, to the highest summits of Blackdown, and 
even of the distant and insulated ridge of Haldon, on the west of the 
valley of Exe, beds of angular and slightly rolled chalk-flints (which 
can be identified by the numerous and characteristic organic remains 
which they contain) are of frequent occurrence; similar beds are found 
also on the green sand summits that encircle the valleys of Char- 
mouth and Axminster; large and insulated masses of chalk also occur 
along the coast, from Lyme nearly to Axmouth, and in the interior 
at AVidworthy, Membury, White Stanton, and Chard; and these at 
distances varying from 10 to 30 miles from the present termination of 
the chalk formation in Dorsetshire, though within the limits of the 
original escarpment of the green sand. 
These facts concur to show, that there was a time when the chalk 
covered all those spaces on which the angular chalk-flints are at this 
time found ; and that it probably formed a continuous, or nearly 
continuous, stratum, from its present termination in Dorsetshire, to 
Haldon, on the west of Exeter 
From the correspondence observed by Mr. Wm. Phillips, between 
* There is also reason to think that the plastic clay formation was nearly coextensive 
with the chalk, for on the central summits of Blackdown there are rounded pebbles ot 
chalk-flint, which resemble those found in the gravel-beds of the plastic clay formation 
at Blackheath : and on the hills that encircle Sidmouth there are large blocks ox a sili¬ 
ceous breccia, composed of chalk-flints united by a strong siliceous cement, and differing 
from the Hertfordshire pudding-stone only in the circumstance of the imbedded flints 
being mostly angular, instead of rounded, as in the stone of Hertfordshire: a variation 
which occurs in similar blocks of the same formation at Portisham, near Abbotsbury, 
and elsewhere.—The argument, however, arising from the presence of these blocks and 
pebbles is imperfect; as it is possible, though not probable, they may have been drifted 
to their actual place by the diluvian waters, before the excavation of the valleys. 
