408 MK. F. W. HAKMER ON THE [Aug. I9OI, 



several miles in length, facing the Gulf of Giens, was covered, from, 

 ■end to end, with the shells of dead molluscs, while upon that facing 

 the east, towards the roadstead of Hyeres, not a single shell was to 

 be found. The reason for this was obvious : the north-westerly 

 mistral was then blowing upon the western beach, causing con- 

 siderable surf, while upon the other, where no shells occurred, 

 protected as it was by the isthmus, the sea was perfectly calm. 

 This incident seemed to throw light on a difficulty which had 

 perplexed me for many years. 



The Crag deposits referred to, originating as beaches against the 

 shore, or as shoals in shallow water, as I have endeavoured to show 

 in a former paper,^ were the littoral accumulations, during later 

 Pliocene times, of the English margin of the North Sea, which then 

 •extended somewhat farther westward than it does at present. They 

 are composed of loose sand, and, as is well known, contain every- 

 where, and in inconceivable profusion, over a more or less con- 

 tinuous area of 60 miles from south to north, the drifted and often 

 fragmentary shells of dead mollusca. 



At present, dead shells are but seldom met with on the eastern 

 shores of the counties of Norfolk and Suffolk, although on rare 

 occasions they are cast up there in greater or less abundance. One 

 may usually walk for miles along the beach at Yarmouth or 

 Lowestoft without finding more than a chance specimen. That this 

 is not due to any absence of moUuscan life from the adjoining sea, 

 my son. Dr. Sidney F. Harmer, F.R.S., and I have ascertained by 

 ■dredging. The conditions under which the Crag beds were de- 

 posited must therefore have been different from those now obtaining 

 in the same area, and the idea suggested itself to me that easterly 

 gales might have been prevalent then in that part of the North Sea, 

 rather than those from a westerly quarter, as at present. 



Investigating the matter further, I ascertained, during a visit in 

 1899 to the coast of Holland with my friend. Dr. J. Lorie, of 

 Utrecht, that the beaches of that country are as plentifully strewn 

 with the shells of dead molluscs as were those of East Anglia 

 •during the Crag Period. Enormous quantities of shells are 

 constantly collected on the Dutch shores for lime-burning, and I was 

 informed by Dr. Hoek, the Superintendent of the Zoological Station 

 .at the Holder, that the shell-gatherers find their best harvest after 

 storms attended by westerly winds." 



The accumulation of shell-beaches in Western Europe is local 

 Tather than general, but they are common on those coasts of France 

 and of the British Isles, facing the west, which are exposed to storms 

 from the Atlantic, and rare in the East of England, though they 

 •occur on the north-eastern coast of Scotland, as at St. Andrews, 

 where easterly gales are more frequent in winter than they are 

 farther south. Prof. M'Intosh, writing from that town, informs 



1 Quart. Journ. Geol. Soc. vol. Ivi (1900) p. 728. 



^ I noticed also two powerful steam-dredgers at work in a disused channel 

 of the River Maas, near the Hoek van Holland, now nearly silted up, which 

 iraise, I was informed, 100,000 tons of dead shells annually. 



