128 MR. F. W. HARMER ON THE GLACIAL DEPOSITS 
are coloured red. They do not form continuous sheets as do 
the boulder-clays and the sands before referred to, but occur 
in isolated masses, sometimes in considerable thickness and 
extent, often occupying high ground, as at Poringland and 
Mousehold Heath. They are well developed at Wymondham, 
Bowthorpe, Dereham, and elsewhere in Mid-Norfolk. 
Similar gravels are found in other parts of the East of 
England, in association with the glacial deposits. They 
represent, in my opinion, a distinct stage in the Pleistocene 
period, that of the melting of the inland ice, and of the 
torrential streams which accompanied it, the different masses 
probably indicating, when traced from south to north, suc- 
cessive pauses in its retreat. In places these gravels contain 
chunks of Chalky boulder- clay ; at others they are overlain 
by thin layers of it. Sometimes they present but little sign 
of stratification, many of the stones having a vertical or 
inclined position ; on the other hand they are sometimes 
obscurely stratified, and frequently contain horizontal 
thread-like layers of sand or loam. They may be regarded, 
I think, as fluvio-morainic, accumulated near the edge of the 
retreating ice. They are more common in Norfolk in the 
region covered by the chalky kind of boulder-clay than in the 
district of the Chalky-Kimeridgian drift of Suffolk. One isolated 
mass of these gravels, that of Tiptree Heath in Essex, forms 
a symmetrical ridge covering an area of six miles in length by 
one mile in width ; this may represent, I consider, a true 
terminal moraine. The way in which the ridge rises suddenly 
and sharply from the lower ground surrounding it is very 
striking, and is well shown on one of the admirable contour 
maps (No. 26, Essex) published by Bartholomew & Co. 
I have observed some small chunks of Chalky boulder-clay, 
similar to those met with at Wymondham, in the Tiptree 
gravel, at a section near the point where the road from 
Kelvedon crosses the ridge. 
The general absence of such well-marked terminal moraines 
from the Chalky boulder- clay region of Norfolk and Suffolk 
may be explained by the view that the ice travelled 
further than the material it carried with it ; most of 
