96 
THE LOWER SEVERN PLAIN DURING THE 
GLACIAL PERIOD.* 
It’s a far cry from Yorkshire to the Lower Severn, but the 
Glacial geologist less than most naturalists can afford to 
limit his horizon within parochial bounds. He contemplates 
the effects of causes geographically as remote as Scandinavia, 
and in like manner looks from causes operating in the vale of 
York to effects produced in the Severn basin. 
When the great Scandinavian ice-sheet invaded the shores 
of England, it profoundly disturbed and deranged the whole 
drainage — ice as well as water — of our eastward-sloping 
valleys. All the natural outlets to the east were closed, and 
waters that would, under ice-free conditions, have found an 
escape by the Humber, the Wash, or perhaps the River Lea 
in Essex, were impounded against the midland watershed to 
form lakes that found their lowest, and therefore their only, 
escape by gaps in the divide between the eastern and the 
western river systems. Thus it came about that the Severn 
received, besides the drainage of its own hydrographical basin, 
great volumes of water from the north, the west, and the 
east of England. Much of this water came from the country 
that stood above or beyond the reach of the glaciers, but a 
far greater part was melt-water from the ice-sheets and 
glaciers themselves. It may well be supposed that a good 
deal of rock-detritus was rafted over on ice-floes, and in other 
ways took advantage of a ‘ lift ’ from floating ice. and the 
gravels and ' diluvium ’ in general in the Severn basin possess 
a special interest to students of the Glacial Deposits from the 
evidence that they afford of this operation. We have long 
known that Red Chalk, a distinctive East Coast rock, is 
recorded from the Severn basin, as well as rocks from northern 
(Scottish and Cumbrian) sources, but a critical re-examination 
of the whole of the evidence has been long overdue. We are 
pleased to see that a veteran geologist, Mr. J. W. Gray. F.G.S.. 
has undertaken the task, and in the paper cited sets himself 
to a careful recital of previous records with a large body of 
additional facts from his own observations and a modest 
amount of theory of his own. He, of course, rejects the 
Murchisonian ‘ Straits of Malvern.’ and ascribes most of the 
drift deposits of the Lower course of the Severn to ‘ derivation 
from moraines left by ice-sheets that approached the district 
from the north and east.’ ‘ Other parts may be remnants of 
Tertiary Gravels.’ He detects no signs of advance of the ice 
in a southerly direction beyond Lepton Warren and Salwarpe. 
* J. \Y. Gray, F.G.S., ‘ Proc., Cotteswold Xat. F.C.’, Vol. XVII., part 
3, 1912, pp. 365-3S0. 
Naturalist, 
