114 MR. F. W. HARMER ON THE GLACIAL DEPOSITS 
correspondence between the two, and the continuous char- 
acter of this deposit over the region in question. 
The student might thence walk to Cawston, two miles 
to the south. On the right hand of the road from that 
village to Sail, where it crosses the Great Eastern 
Railway, there is a large pit of typical Chalky boulder-clay, 
full of detritus from Lincolnshire, the moraine of the inland 
ice. The marked difference between the Cawston and Heydon 
deposits is as striking as the correspondence between the 
latter and that of Weybourne. A short distance east of 
Cawston the Norwich brick-earth comes on suddenly. Near 
the road from that place to the Woodrow Inn there is a pit 
of the latter, showing evident signs of glacial disturbance.* 
To what distance southward over the Eastern Counties 
the North Sea glacier once extended cannot be ascertained 
with certainty. The North Sea Drift disappears abruptly 
as a continuous sheet to the south of the line A B on the 
contour map, although out-lying fragments of it are exposed 
near Loddon, Lowestoft, Beccles, Harleston, and Bury St. 
Edmunds. Possibly other outliers may exist also under the 
inland drift of Suffolk. That a lobe of the North Sea ice- 
sheet entered the Fenland at this period through any opening 
then existing where is now the Wash, seems more than 
probable. Indeed Messrs. Rastall and Romanes have recently 
shown that many Scandinavian and North British erratics, 
similar to those of north-east Norfolk, are to be found in 
Cambridgeshire, an indication in their opinion, as in mine, 
of the former presence in that region of the North Sea ice.f 
* I should point out that the maps of the Geological Survey repre- 
sent the marly clay of Weybourne and Heydon under the same colour 
(blue) as the Chalky boulder-clay of Cawston and the region to the 
south of it. In our map of 1872, Wood and I regarded these as essen- 
tially distinct, both in character and age, a view which I still hold. On 
the other hand, the Survey maps distinguish between the Heydon and 
Weybourne marl and the Cawston and Norwich brick-earth (coloured 
orange), deposits which though differing lithologically, I believe to 
be of similar age, and to have originated under similar conditions. 
Mr. H. B. Woodward, however, who subsequently mapped this district, 
and probably knows it more intimately than anyone else, seems now 
disposed to adopt my view. 
f Quart. Journ. Geol. Soc., vol. lxv (1909), p. 246. 
