CONTAINING FLINT IMPLEMENTS, AND ON THE LOESS. 
309 
of from 90 to 150 feet above the river, and the low-level gravels those up 
to 30 or 40 feet above the river. In fact, no definite line can properly be 
drawn, as all the terraces are members of one series : nevertheless it is not 
only for the sake of convenience that this division is adopted ; it is to a 
great extent conformable to the phenomena as they exist ; for the great bulk 
of these quaternary gravels occur, one portion on terraces at or near 100 
feet above the Somme, and another portion at or near 30 feet. The gravels 
on both levels, especially the lower one, are often covered by Loess — the low- 
level gravel being constantly buried under it and hidden, whilst both Loess 
and gravel disappear under the recent alluvium. The heights are taken in 
part from the French Ordnance Maps ; the others are from observations I 
have taken with the aneroid barometer. The general topographical outlines 
of the districts are also taken from the French Ordnance Maps. 
Fig. 3 shows the valley-gravels along part of the valley of the Waveney. The scale is 
that of the Ordnance Map, from which the topographical outlines are taken. 
The same observations apply to these gravels as to those of the Somme ; only 
the series is more limited, and the heights to which they rise is not so great ; 
50 feet is about the extreme height. The Loess is here in so rudimentary a 
state that I have not laid it down. The heights at Floxne are from the 
levellings given in my former paper, or are taken with an aneroid. 
Not to interfere with the details, the roads, and all except a few chief places, are 
omitted, but it is easy to find any particular spot by transfer to the French and English 
Ordnance Maps, on the scales of which these plans are made. 
The dotted lines across the valleys refer to the lines of section given in woodcuts 
pp. 253, 258, and 259. 
Note . — There is some obscurity in the shading, arising from a mistake of the artist in taking my rough MS. 
sketch instead of the Ordnance Maps which accompanied it for his guide in these topographical details. I 
must refer to the Ordnance Maps therefore for the more correct delineations of the surface. Some errors of 
geographical detail have from the same cause crept into the Map. 
INDEX OF CONTENTS. 
§ 1. Introductory Remarks 
§ 2. Geological Position of the Flint-implement-hearing Beds 
§ 3. High- and Low-level Valley-gravels 
§ 4. The Brick-earth or Loess 
§ 5. Organic Remains of the Valley-gravels 
§ 6. Climatal conditions. Excavation of the Valleys . . 
§ 7. The question of Time and Succession 
Appendix. List of Testaceous Mollusca 
Page 
247 
251 
264 
286 
298 
306 
