Dr. Irving—Surface- Changes in London Basin. 211 
[V.—On Post-Hocent Surrace-CHances in THE Lonpon Bastn.! 
By A. Irvine, B.A., D.Se. (Lond.), F.G.S. 
HE Quarterly Journal of the Geological Society, for 1892,? 
contains a paper by Mr. H. W. Monckton, F.G.S., embodying 
a useful and valuable collection of observations tending to throw 
additional light upon the history of the surface-changes, which have 
taken place in the higher parts of the London Basin in later Tertiary 
and Quaternary times. The theoretical views put forward in 
that paper have not, however, altogether the novelty which the 
author seems to claim for them. He is wrong in coupling my name 
with that of Prof. Rupert Jones as an advocate of a partial marine 
origin of the gravels, and so claiming novelty for the theory (p. 45) 
“ that all the gravels in the area dealt with were formed after it had 
for the last time risen above the sea.” A few quotations will put 
this in a clear light. 
(a) In 1883,3 I spoke of the plateau-gravels as probably ‘“accu- 
mulations produced by powerful river-currents converging possibly 
to a common estuary” (p. 23), and as having been deposited at a 
time when “the drainage-system of the area was quite different from 
that which is seen at the present day” (p. 26). The intermediate 
pages are mainly occupied with a discussion of the conditions under 
which I conceived then that their deposition had taken piace. Mcre 
recent observations have but led to the confirmation of that view, 
and to the dating back of the plateau-gravels to an earlier Tertiary 
stage than I then ventured to assign them to. I deferred then to 
the opinion of Prof. Rupert Jones, that the sea had had a share in 
the deposition of the secondary or terrace-gravels; but more recent 
and more extended observation compelled me to abandon the idea 
of marine action, even for them. 
(6) In 1890,‘ I spoke of the fluviatile transport of the materials 
from the Wealden uplands to the south, and of the “transport of 
the angular flint-material by rivers from the Weald across the north- 
ward sloping plateau of Hocene land” (p. 558); of the materials 
being ‘carried northwards and deposited in lines of river-drainage 
or spread out on flats, where the declivity of the plateau diminished,” 
comparing this (in a footnote) with my own observations in former 
years of the “gravelly detritus laid down by Alpine rivers, as they 
debouch upon the Plain of Bavaria” (p. 559) ; of their stratification, 
in most cases as clear as those of the low-level gravels of the present 
Thames Valley, as “a fact, which seems to point clearly to their 
river-origin” (p. 560); and of their remaining as ‘“‘indexes of 
ancient Pliocene lines of drainage, having preserved the present 
hills from degradation, while the originally higher ground has been 
scored with the present valley-system” (p. 561). Other passages 
of similar import might be quoted from the same paper, and from a 
1 This paper was written some months ago, but has unfortunately been delayed in 
publication from want of space.—Epir. Grou. Maa. 
2 Q.J.G.S. vol. xlvii. pp. 29-45. 
3 See Proc. Geol. Assoc. vol. viii. 4 Q:J.G.S. vol. xlvi. 
