GEOLOGY OF THE NORWICH DISTRICT 57 
a striking series of contortions, to which the general term ‘ Contorted 
Drift ’ has been applied. Dr. G. Slater has traced out, from Happisburgh 
to Weybourne, a succession of built-up mounds of Chalk, Pliocene deposits 
and Till, of drumlin-like form, separated by basins of deposition con- 
taining mainly sandy deposits. ‘The ice which gave rise to the phenomena 
and formed the Cromer Ridge appears to be that which produced the 
Great Chalky Boulder Clay. Following a period of recession, there was 
a fresh ice-advance which Dr. Solomon has termed the Little Eastern 
Glacier. Its outwash gravels include those banked upon the Cromer 
Ridge, like the ferruginous cannon-shot gravels of Holt. Inland it 
produced the Upper Chalky Drift. 
At Hoxne, a short distance south of the boundary between Norfolk 
and Suffolk, the beds overlying the Chalky Jurassic Boulder Clay and 
underlying the Chalky Drift have long been famous for the evidence they 
furnish of mild interglacial conditions and the occupancy of the area by 
Acheulian and ‘ early Mousterian’ man. ‘The plant and animal remains 
are indicative of climatic oscillations, but dominantly of a temperature at 
least as mild as that of the present day. 
Resting against the western end of the Cromer Ridge at Morston, is a 
raised beach at a height of about 25 ft. above O.D. This beach, which 
was first recognised by Dr. Solomon, marks a submergence of the area 
after the retreat of the Little Eastern Ice. The beach is capped by 
brown boulder clay like that found at Holkham and Hunstanton, its easily 
recognisable characters being altogether different from those of any of 
the earlier boulder clays, but similar to those of the Hessle Clay of York- 
shire and Lincolnshire. It is not found south of Hunstanton, nor are 
its characteristic erratics (dolerites, porphyrites, and dark blue greywacke 
grits) and minerals (especially pyroxenes) detectable in quantity on the 
Cromer Ridge or in outwash gravels. The ice appears to have been 
‘dead’ by the time it reached Norfolk. At Hunstanton, Mr. J. Reid 
Moir has found in the Brown Boulder Clay implements which appear to 
be Middle Aurignacian, and one may assume from this that the glacial 
phase would correspond to that of the cold Magdalenian phase, of which 
evidence is found elsewhere in Europe. 
The chief river systems of Norfolk, like those of the Yare and Waveney, 
have been excavated through the Norwich Brickearth and the overlying 
sands and gravels, but are earlier than the Chalky Boulder Clay which 
rests on their valley slopes. ‘They were thus carved out in a period of 
great erosion between the first and second glaciations of the area. But 
the river Bure, river Glaven and others rise in the Cromer Moraine, 
hence these smaller streams and valleys must have developed during or 
after the retreat of the Little Eastern Glacier. The Norfolk Broads, 
many of which are connected with the river Bure, are of still more recent 
formation. The mode of origin of the Broads was explained by the 
late Prof. J. W. Gregory as follows. The area of north-eastern Norfolk 
as a whole was a drowned estuary in post-glacial times. ‘The once con- 
tinuous sheet of water was gradually silted up with detritus brought 
down by rivers, the process being aided by the accumulation of shingle 
and sand drifted southwards by tidal currents, with consequent ponding 
