File:The Quarterly journal of the Geological Society of London (13859822653).jpg

IN THE COtfTOETED DEIFT OF CEOMEE.
227
Tellina balthica

but I consider, with Messrs. H. B. Woodward, J. H.
Blake, and Clement B-eid, that the presence of this one shell is an
unsatisfactory test of the climate being glacial. JSTo doubt the
climate was gradually changing

but I could see no evidence of ice-
action below the till. The generally undisturbed nature of the Crag-
beds negatives the supposition.
Description of the Cromer Till and Contorted Drift.
The lower part of the Cromer Till is, in places, stratified. This
I distinctly noticed in more than one place

and it is shown in the
section taken at right angles to the shore (fig. 5, a) between Sher-
ringham and Cromer. In another place I noticed that the till rested
Fig. 5. — Section cut out by a Stream at right angles to the shore
between Cromer and Sherringham.
a. Stratified till.
b. Unstratified till.
c. Nest of gravel.
d. Contorted sands and gravels.
upon white stratified sand

and also at a point near Sherringham an
eroded surface of black loam was capped by red gravel. It is not easy
always to distinguish between the preglacial beds and the incoming
glacial, especially when the base of the cliffs is encumbered with
talus

and even where a vertical face is to be found, if not perfectly
fresh, it frequently gets washed over with sand from above, rendering
it necessary to scrape it down before its nature can be disclosed. Mr.
J. H. Blake says*, " Where the unstratified rootlet-bed is to be seen,
this line is very marked

but where the rootlet-bed has been en-
tirely denuded, it is frequently not so well marked, from that and
the following reasons. There are sometimes sands &c. immediately
above and below this bed of a similar colour and nature, which, when
the bed itself is entirely denuded, come together and give an ap-
pearance of a break in the series." The till may therefore be
described as sometimes passing down into semistratified beds, itself
being usually unstratified, but occasionally partially so, as we see
is also the case with the marine Boulder-clays of West Lancashire.
Upwards it usually passes into the Contorted Drift in an indescri-
bably confused sort of manner, but occasionally displays a very

Presidential Address, Norwich Geol. Soc, Session 1879-80, p.