252 
ME. PEESTWICH ON THE GEOLOGY OF THE DEPOSITS 
of the higher hills. The two series bear nevertheless a definite relation one to the 
other. They both consist of debris derived from rocks in the valleys through which 
the present rivers or their tributaries flow, and they both occasionally contain organic 
remains, of which the greater number of species are common to the two. Both series 
may be considered as “valley-gravels;” but for the sake of distinction I purpose calling 
that which occupies the bottom of the valleys, and reaches to a comparatively small 
height above the river-level, the “ low-level valley-gravels,” whilst to that found on the 
adjacent hills, I would apply the term “ high-level valley-gravels.” The height of the 
latter above the valley is variable ; and though generally limited to one main platform, 
it is not always on the same level, and there are cases of minor intermediate terraces 
between the extreme levels. The heights are of course relative one to the other, and 
not directly to the sea-level. 
Valley of the Waveney . — The levels recorded in my former paper establish the fact 
that the flint-implement-bearing deposit of Hoxne is at a height of 40 feet above the 
Gold Stream, and 50 feet above the Waveney, of which the Gold Stream is a tributary. 
Mr. Evans and I found a very similar deposit, also overlying the Boulder Clay, at Athe- 
lington, a few miles higher up the valley of the former stream. In following the course 
of the Waveney, from above Diss to the sea at Lowestoft, terraces of gravel are found at 
distant intervals on the adjacent hills. They never extend far from the valley, and the 
intermediate higher but flat ground between the river-valleys invariably presents bare 
tracts of Boulder Clay. It is particularly between Diss and Harleston that these terrace- 
gravels are best exposed, and where I have determined with some care their extent and 
development (Plate V. fig. 3). I have found them on the right bank of the Waveney, 
at Stutston Common, Oakley, and Shotford Heath, lying upon the Boulder Clay ; and 
on the left bank at Scole, Billingford, Thorpe Abbots, and Needham. Thence to the sea 
they may be traced at intervals on both sides of the valley ; but they seem gradually to 
fall to a lower relative level. At the places above mentioned, on the contrary, they occupy 
a tolerably regular level of from 40 to 60 feet above the valley, are from 5 to 12 feet thick, 
and rarely exceed a quarter of a mile in length, or more than 200 to 400 feet in width. 
They consist chiefly of a mass of subangular flints, with pebbles of siliceous sandstones 
and of the older rocks, in a matrix of ochreous sand and clay. No organic remains have 
been found in them. The low-level gravel is not often exposed, being generally covered 
by alluvial deposits. It may, however, be seen at Oakley and at Needham, and has 
been reached at various places under the recent alluvium of silt and peat. Care must 
be taken to distinguish these gravels from those which underlie the Boulder Clay in this 
district. The latter are more sandy and far more distinctly stratified*. They may be 
seen in superposition in a pit on the hill above Oakley Street ; in contact with the high- 
level gravel at Needham near Harleston, and at Moor Bridge near Hoxne ; and lying on 
the Boulder Clay at Thorpe Abbots. The following section, taken across the valley 
* The great number of pebbles of white quartz is one of the chief features which serves to distinguish the 
gravel under the Boulder Clay from the valley-gravels. 
