214 Dr. Irving—Surface- Changes in London Basin. 
during and since the Glacial Epoch. I put the matter very briefly, 
but plainly, in my Windsor lecture, to which reference has been 
already made. 
Again, on pages 44 and 45 of the paper, with which I am now 
dealing, this ghost of the sea having “flowed in the Thames Valley 
since these [Glacial] Gravels [of the north side of the valley ] were. 
deposited,” is exorcised, in order, as it seems, to enable the writer, 
who uses the spell, to “reject the theory, which assigns the con- 
tortions observed in clay-beds near Wokingham, to bergs or floes of 
ice, which floated in waters, that filled that valley up to 240’ above 
O.D.” The simple reply is, that those, who, like myself, have 
adopted such a view, are responsible for what we have said, and not 
for any extraneous ideas, which another writer’s imagination may 
have read into it. Asa matter of fact, and as Mr. Monckton’s own 
testimony (loc. cit.) goes to show, we do find just what we should 
_ expect in such a submerged shallow valley: we find on the northern 
slopes glacial detritus; and we find on the southern slopes materials. 
derived immediately from the plateau-gravels and from the strata of 
the Bagshot terrain of the higher country, to the south, as the out- 
crops of these receded southwards with the sub-aérial erosion of the 
district. Both sets of material would be more or less mingled 
together along a roughly-median zone of such a submerged valley, 
just as one may often see, in an isoclinal longitudinal valley of a 
great mountain-chain (such as the Alps) detritus from the crystalline 
rocks on one flank of the valley mingled together in the most indis- 
criminate fashion with detritus from the clastic rocks on the other 
flank, only needing such a widening of the valley by erosive agencies 
as would admit of such fluviatile action coming into play, as has. 
evidently given us the stratified low-level gravels of the present Thames 
Valley, which were long ago commented on by one of the most 
sagacious of British geologists, the late Prof. John Phillips, F.R.S.? 
One might easily cite the low-level stratified drifts of the Severn 
Valley, and of many another ancient river-valley, as showing this. 
commingling of local materials with glacial remanié, were it not 
that to deal in this way, with what is but a commonplace of physical 
geology, would only serve to weary the reader. And as the low- 
level gravels are stratified, so also is it quite an ordinary thing for 
glacial materials themselves to have been partially stratified; and 
that without requiring any long “inter-glacial’’ periods for the 
supply of the floods necessary to do the work; since the increased 
fluviatile action arising from the melting of the snow and ice, as the 
climate gradually underwent amelioration, would be sufficiently 
potent as an agent for the work to be done. I will only point out 
here that in the discussion of my paper on the platean-gravels. 
(supra cit.) in the year 1890, it was admitted. that ‘such contortions. 
as described were generally accepted as evidence of snow or ice,” 
and that by the very person who, in December, 1891, rejects. 
such an explanation of the case then under consideration, yet 
without bringing forward anything by way of an argument in support 
1 See his ‘‘ Geology of Oxford and the Valley of the Thames.” 
fe SS ae 
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