vol. xx. (2) NOTES ON COTTESWOLD-MALVERN REGION 119 
submergence in Glacial times have been discovered, this 
explanation may be disregarded. 
The existence of small lakes in the Severn Valley is possible, 
yet it is difficult, in view of the present contours, to show how 
water could have been held up to a sufficient height to allow 
of the stranding of Drift bearing ice-floes on Apperley Hill, 
137 feet O.D. and 100 feet above the present stream, or to 
account for the rounded and smooth Jurassic gravels at 
Stroud at 150 feet O.D., and at Cheltenham 320 feet O.D. 
The supposed barrier would require one or more of the following 
conditions : — 
1. The accumulation, to a sufficient height, of debris 
carried down by the rivers. 
2. Unequal elevation of the land by tilting movements 
due to the imposition and release of the weight of ice during 
the Glacial Period. 
3. The advance of ice from the Irish Sea and South Wales 
into the Bristol Channel. 
4. The lowering in late Glacial times of a ridge extending 
across the river. 
In support of the first it is proved beyond doubt that 
enormous quantities of debris were brought down the Severn 
from the melting ice front and from terminal moraines above 
Worcester, as' well as from areas drained by tributary streams, 
especially the Teme, Avon, Leadon, and Frome, and deposited 
in and near the rivers. The gravels on the east of the Severn 
at Gloucester and between Stroud and Stonehouse bear witness 
to this transportation of a mass of Jurassic detritus. 
The second assigned cause is difficult to establish, but it 
is not improbable that earth movements produced changes of 
level in the Severn estuary during the Glacial Epoch ; the signs 
of elevation and depression in that region, such as the submerged 
forest at Westbury, are, however, of a minor character and of 
post-Glacial date. 
An invasion of the Bristol Channel by ice sheets to an 
extent that may have assisted in obstructing the stream 
is possible, but there is no authentic record of the discovery 
