155 
THE SOUTHWARD MOVEMENT OF BEACH-MATERIAL 
ACROSS THE HUMBER GAP. 
ALFRED HARKER, M.A,, F.G.S., 
St. John’s College, Cambridge. 
SOME time ago, in correspondence with Mr. F. M. Burton) 
I ventured to point out that much greater caution is needed 
ard movement o ach-mater s here an impor 
factor, the Lincolnshire boulders being probably derived to 
a large extent fro ess er published in 
‘The Naturalist’ for last year (pp. 133-138) Mr. Burton quoted 
this opinion, but dissented from w, in the April 
number, returns to the subject, fortified by the support of two 
engineer authorities, Mr. Wheeler and Mr. A. Atkinson 
o the facts adduce these gentlemen I do not take 
any exception, but i conclusions drawn from those facts 
ut in 
certain essential considerations seem to be left out of account. 
The beach movement is admitte Mr. ihn indeed, objects 
to my expression ‘ powerful tidal scour,’ and here I am willing 
to accept emendation; but as he tells us that ‘there is a drift of 
material along the beach from N. to S.,’ and again that ‘the 
banking up of the shingle and also the travel along the shore is 
due entirely to tidal action,’ our difference is evidently one of 
transport was much greater formerly than it has been during 
the last thirty or forty years, when groynes have been erected 
at numerous points and the getiidial removal of shingle 
prohibited. 
Now, I have not, as Mr. Atkinson suggests, ‘overlooked the 
existence of the wide and deep embouchure of the Humber’; 
but, as Mr. Burton remarks in another connection, it is not with 
the present day only that we have to deal. ‘There is no drift 
across the Humber,’ says Mr. Wheeler. ‘This drift collects at 
Spurn Point.’ True, but it is manifest that this process cannot 
go on indefinitely. Mr. Clement Reid, in the Geological Survey 
Memoir, ‘The Geology of Holderness,’ estimates the average 
growth of Spurn Point during the last 200 years at 13% yards 
per annum; less under the present artificial conditions, but 
May 1899. 
