550 S. V. Wood,jun. — American and British Surf ace- Geolog y. 
undergone destruction there by its pressure and motion. 1 For several 
miles round Thetford upon the high ground the Upper Glacial presents 
a very peculiar condition, as it consists of a gritty sandy kind of 
material, intermingled in which are often masses of stiff blue morainic 
clay, which resemble the clay of the Upper Glacial elsewhere, the 
whole resting upon glaciated chalk. This morainic material, which 
forms some of the lightest and most barren heatli land in England, 
appears to be moraine formed by the destruction of the Lower and 
Middle Glacial deposits (and possibly also of some of the earliest 
deposited Upper Glacial) during the time when the inland-ice was 
pressing upon the Western side of this land-belt; and it terminates 
quite abruptly, and gives place to the stiff heavy clay which forms 
the usual character of the Upper Glacial, just where the Middle 
Glacial sets in beneath it. The Chalk also beneath it is glaciated, 
as it usually is on the west of the line to which this land-ice reached. 
The state of things which thus existed after the earliest part of 
the Upper Glacial had accumulated appears to me to throw light 
upon the age of the well-known lacustrine bed two miles from the 
River Waveney, and situated at Hoxne, on the table-land out of 
which the valley of this river is excavated. This bed of laminated 
brick-earth and sand, with freshwater mollusca and Pakeolithic 
implements, was elaborately described by Mr. Prestwich in the 
Phil. Trans, for 1860 and 1864, and shown to occupy a small 
basin-like hollow in the chalky clay. I examined the locality with 
Mr. Prestwich’s sections some years ago, and could detect no error 
in them. 2 The deposit. is so placed that on one side it has been 
denuded by the excavation of a valley which is lateral and tributary 
to that of the Waveney, viz. the Goldbrook Valley. This fact, and 
the occurrence of some gravels capping the chalky clay along the 
edges or brows of the main valley, induced Mr. Prestwich to con- 
tend that the accumulation of the brick-earth and gravels must have 
preceded the excavation of the Waveney Valley, because, if not, it 
would be necessary to infer either that the valley was filled at the 
time with the sea or by freshwater. The first of these alternatives 
was rejected for want of any evidence of it, and as being repugnant 
to the facts affecting the case ; while the latter was evidently a 
physical impossibility. Hence the view adopted was that the Hoxne 
1 The limit up to which this inland-ice pressed upon and destroyed all the pre- 
ceding glacial deposits is marked, as nearly as can be defined, by a line which, start- 
ing in North-west Norfolk, a little east of Docking, runs south between SwafFham 
and East Dereham, and between Thetford and East Harling, where the ice began to 
draw in to form the glaeier-tongue which passed tlirougli the Waveney Valley ; from 
whence it runs by Bottesdale, south of which the glaeier-tongue through the Gipping 
Valley went off. From thence the line runs westwards, and is more difficult of defi- 
nition. The tongue which passed down the valley of the Wensum and Yare probably 
went off near the starting-point of this line. 
2 I think it, however, probable that the chalky clay and underlying (Middle 
Glacial) gravel do not possess the regulär horizontality which Mr. Prestwich gives to 
them ; and also that between them and the chalk some of the Contorted Drift, out of 
which the valley was first interglacially excavated, may be present. The representa- 
tion given by Mr. Belt in the Quart. Journ. of Science for 1876 does not in any 
respect agree with my view of the facts of the case. 
