Notices of Memoirs — F. W. SarniPr — Pliocene Climate. 509 



III. — TfTR Mrteouologigal Conditions of North - Western 

 Europe during the Pliocene and Glacial Periods.' By 

 F. W. Harmer, F.G.S. 



"VTO satisfactory explanation lias yet been offered as to the conditions 

 l\ under which originated the great sheets of shelly sand known 

 to geologists as the Upper Crag, the littoral deposits of the North Sea 

 in Pliocene times, which contain everywhere (over an area in East 

 x\nglia more than sixty miles in length) the dead shells of mollusca 

 in the most extraordinary profusion. No such accumulations are 

 now taking place on the shores of Norfolk and Suffolk, although 

 molluscan life is more or less abundant in the adjoining seas. On 

 the coast of Holland, on the contrary, dead shells are exceedingly 

 common. 



The occurrence of such debris is local rather than general, and 

 seems to be due, sometimes to currents, but more frequently to 

 the action of stormy winds, which agitate the sea bottom to a greater 

 or less depth. An examination of the daily weather charts issued 

 by the Meteorological Office shows that movement of dead shells 

 towards the shore at any place is for the most part in the direction 

 of the gales which may be prevalent. At present the cyclonic 

 disturbances, to which East Anglian storms are due, pass as a rule 

 with their centres to the north-west of that district; and hence 

 south-westerly and westerly gales are there common, and shelly 

 debris is driven on to the shores of Holland, and not on to those 

 of the east of England. It would seem, therefore, that during the 

 Pliocene epoch strong winds from the east must have prevailed 

 in the Crag area. At an early stage of the Red Crag period, mollusca 

 now confined to the Arctic Circle had begun to establish themselves 

 in the Crag basin, so that the glaciation of Scandinavia, attended 

 with anticyclonic conditions over that country, had probably then 

 commenced. At present, when Scandinavia is anticyclonic, storm 

 centres may be diverted from their usual course towards the south, 

 as was the case, for example, in October, 1898, causing south- 

 easterly and easterly gales, with rough sea on the eastern coasts 

 of England. It is suggested that such conditions may have frequently 

 prevailed there during the Crag period. 



The meteorological conditions of the Northern Hemisphere during 

 the Glacial epoch must have been widely different from those of 

 our own time. At present the accumulation of ice-sheets in the 

 Arctic regions is local rather than general ; Greenland, for example, 

 being glaciated, while the north of Scandinavia enjoys a milder 

 climate. The latter is due, partly to the Gulf Sti-eam, but partly 

 also to the prevalence of south-westerly winds, caused by the 

 relative positions occupied by areas of high and low pressure. 

 Nansen states that a constant area of high-pressure now exists over 

 Greenland, and that the winds blow outwards from that country 

 in all directions. Similar conditions probably obtained during the 

 Glacial Period over the great ice-sheet of Northern Europe, producing 



^ Bead in Section C (Geology), British Association, Dover Meeting, Sept. 1899. 



