OF NORFOLK AND SUFFOLK. 
117 
At Norwich, moreover, the great valley of the Wensum 
has been excavated through the older glacial beds, the Chalky 
boulder-clay being found within the valley, at a lower level 
(see fig. 5). The latter deposit, however, is never overlain 
by the former. 
S.W. N.E. 
Tuck’s Wood Farm. Victoria Ry- Station. Household Reath. 
Trowse. R. Wensum. | 
Fig. 5 . — Section across the valley of the Wensum at Norwich, 
showing the Chalky boulder-clay as a valley deposit, and the anomalous 
position of the post boulder-clay gravels of Household Heath. — F. W. 
Harmer. 
1. Chalk. 5. Chalky boulder-clay. 
2. Crag sands and Pebble beds. 6. Cannon-shot gravel. 
3. Contorted drift (Norwich brick-earth). 7. Valley gravel. 
4. Middle Glacial sands. 
Reproduced by permission of the Council of the Geologists’ Association. 
It does not seem that the North Sea Ice entered the Fenland 
through the Wash Gap during the second glaciation of East 
Anglia, a view held by some glaciologists, as I think it did 
during the first. We find no indication of any ice-movement 
from the Wash towards the west or south-west during the 
deposition of the Chalky boulder-clay ; all the facts tending 
to show that the inland glacier travelled from Lincolnshire 
towards Norfolk across the Fenland and a part of the Wash 
in a south-easterly direction, as shown on the contour map 
by arrows.* 
The plain of the river Witham below Lincoln appears to have 
been occupied at this stage by two ice streams, confluent but 
distinct, one of them due to ice crossing the Chalk 
Wolds of Lincolnshire which left behind it a mass of very 
white boulder- clay, intensely chalky in character, formed by 
the grinding action of the ice upon the subjacent chalk rock ; 
the other, from the Vale of York, which had thence moved 
along the strike of the later Jurassic clays being represented 
by a dark-coloured Jurassic drift, covering a great part of 
the low ground between the Wolds and the Lincoln ridge. 
* This part of the subject is treated in greater detail in my paper of 
1909, referred to on p. 108. 
