OF NORFOLK AND SUFFOLK. 
I2 7 
they are exposed within the valleys, owing to the denudation 
of the latter, but they occur also beyond the periphery of the 
region occupied by the Chalky boulder- clay, where they 
form heaths, on the higher land between the rivers, as at 
Sutton, near Woodbridge. 
Although both these sandy deposits are newer than the 
North Sea Drift, and older than the Chalky boulder-clay, 
I am now inclined to consider them distinct, the first originating 
in Norfolk during the retreat of the North Sea ice, the latter 
being due to water issuing from the margin of the inland 
glacier during its advance. 
At certain localities in South Norfolk and Suffolk the 
Chalky boulder-clay is underlain by finely laminated brick- 
earth instead of by the Middle glacial sands, the connection 
between such beds and the overlying boulder-clay being 
shewn by the fact that they generally resemble each other in 
colour and composition. Probably they were deposited in 
hollows, in advance of the ice and not far from it ; they may 
be observed at some brickyards on the road from Norwich to 
Ipswich, four miles north-east of Forncett Station ; at Boyland 
Hall, three miles east of the same place ; at Woolpit, eight 
miles east of Bury St. Edmunds, and elsewhere. 
The Cannon-shot Gravels. 
The distribution of the coarse gravels for which the above 
name was adopted by Wood and myself because they contain 
occasionally symmetrically rounded flints resembling the 
cannon-balls at that time in use, is indicated on the Contour 
map by small dots ; such flints may probably have been 
formed in “ kettle-holes ” beneath the ice. 
These coarse gravels, which overlie the North Sea drift on 
the one hand, and the Chalky boulder-clay on the other, 
are not distinguished on the maps of the Geological Survey 
from the Middle Glacial sands which underlie the latter, 
being all shown by the same pink colour. They are the 
plateau gravels (No. 10) of our map of 1872,* on which they 
* Loc, cit. 
