vol. xx. (2) NOTES ON COTTESWOLD-MALVERN REGION 
105 
207 , pp. 85-99). The condition of the pebbles may be attributed 
mainly to the combined effects of long-continued river action, 
the movement of flowing soils over frozen surfaces, and solution 
due to the percolation of acidulated waters. Much of the 
material must have been carried several miles by the Frome 
from the original rocks at the head of the valley and the inter- 
vening slopes before reaching the Stroud area, where a small 
lake may have existed. The lake hypothesis is further dealt 
with in Chapter VII. 
The gravels around Gloucester are very variable in 
composition and arrangement, and are largely composed of 
debris from the Cotteswolds, with a smaller proportion from 
the Malveins and a few northern erratics ; and some have 
apparently been deposited in disturbed water, possibly that of 
a shallow lake fed by the Severn and Leadon and streams 
flowing from the hills. The currents appear to have been 
strong enough to carry, in some cases, no doubt, on ice-rafts, 
Jurassic pebbles as far as Highnam on the west of the river and 
Malvernian pebbles to the distance of a mile on the east. 
Some of the pebbles in the Jurassic gravels at Barnwood, 
near Gloucester, are waterworn and rounded, and there is a 
seam of fine light-coloured siliceous sand in the upper part of 
the deposit. The probability that the Gloucester gravels and 
sands are of late Glacial age is indicated by the occurrence, in 
a bed of silt in gravels at Denmark Road, of boulders of once 
frozen “ Cheltenham Sand ” that have evidently been released 
from thawing ice-rafts (66, p. 374). 
III. The Black Flints. 
The Black Flints (Class B) that occur in many places in 
the north-eastern section of the district may generally be 
distinguished from other varieties by their fresher condition 
and larger size. In the gravels at Mickleton Tunnel, Moreton- 
in-the-Marsh, Evesham, and other localities they are, however, 
somewhat waterworn. In the area between Ebrington Hill 
and Moreton the fresh flints are plentiful in the surface soil of 
