LAMPLUGH: GLACIAL SECTIONS. 
245 
fields west of the Dykes Farm. They appear to die out against or 
thin out over, a gravel containing very little chalk. 
In tracing the gravels either eastward in this direction, or 
southward through the town in the drainage sections, the way in 
which they gradually decrease in roughness as we leave the exposed 
chalk surface is very noticeable, and I would again call attention 
to it. 
The bearing of these facts I shall consider in the concluding 
portion of this paper, in dealing with the gravels as a whole. 
The Purple Boulder Clay. The description of this clay given 
in part II of this paper would apply to its character in these sections 
also. It occurs in two well-marked divisions separated by a very 
irregular and intermittent bed of sand or sandy gravel (^c). The 
upper part (^a) in many of the sections showed all the characteristics 
of the " Hessle Clay " of Mr. S. V. Wood, being quite red in colour 
and having ashj^ coloured partings down its joint planes, evidently 
the result of weathering ; but whether it is really the same as the 
top red Boulder Clay of Holderness, and of Flambro' Head, I have 
not yet been able to determine. Of one thing I am certain, that this 
upper division in the town is the same as that marked 3a in the cliff 
sections already published ; which has always been considered as the 
Purple Boulder Clay. 
The intercalary sand and gravel, , which rose in some of the 
sections to a considerable thickness for a short distance but always 
rapidly sank and thinned again, seems to have suffered great erosion, 
and to have been cut down into and often completely removed 
during the formation of the overlying Boulder Clay. It consists in 
some places of pure sand, in others of roughish gravel, but oftener 
an admixture of sand and gravel. 
I consider it to b(? the same bed as the gravel in the cliff section 
to the north (marked 2a in part I), and as the stratified band 
with intermittent sand to the south of the town (marked 3c in part 
II. of this paper). 
The lower division of the Purple Clay requires no special com- 
ment, being identical in character with that of the sections already . 
described. 
