Ch. XX.] 
TERTIARY OUTLIERS ON CHALK. 
283 
Apennines, and Pyrenees, we find the newer formations reposing 
unconformably upon the truncated edges of the older beds, and 
it is clear that, in many cases, the latter had been subjected to 
a complicated series of movements before the more modern 
strata were formed. The latter rise only to a certain height 
on the flanks of the mountains which usually tower above 
them, and are recognized at once by the geologist as having 
been upraised into land when the tertiary formations were still 
forming in the sea. The ancient borders also of that sea can 
often be defined with certainty, and the outline of some of its 
bays and sea-cliffs traced. 
In England, although undoubtedly the greater portion of the 
tertiary strata is confined to certain spaces, we find outlying 
patches here and there at great distances beyond the general 
Jimits, and at great heights upon the chalk which separates the 
basins of London and Hampshire*. I have seen masses of 
clay extending in this manner to near the edge of the western 
escarpment of the chalk in Wiltshire, and Mr. Mantell has 
pointed out the same to me in the South Downs. Near the 
escarpment at Lewes, for example, there is a fissure in the 
chalk filled with sand, and with a ferruginous breccia, such 
as usually marks the lower members of the Plastic clay for- 
mation. From the fact of these tertiary outliers Dr. Buckland 
inferred, ' that the basins of London and Hants were origi- 
nally united together in one continuous deposit across the now 
intervening chalk of Salisbury Plain in Wilts, and the plains 
of Andover and Basingstoke in Hants, and that the greater 
integrity in which the tertiary strata are preserved within the 
basins has resulted from the protection which their compara- 
tively low position has afforded them from the ravages of dilu- 
vial denudation f .' 
We agree so far with this conclusion as to believe that the 
basins of London and Hampshire were not separated until part 
of the tertiary strata were deposited, but we do not think it 
probable that the tertiary beds ever extended continuously over 
* Dr. Buckland, Geol. Trans., Second Series, vol. ii.p. 125. t Ibid., p. 126. 
