LAMPLUGH : GLACIAL BEDS. 
171 
has, no doubt, been at one time of far greater extent, and 
has been so extensively denuded as to leave but this patch 
remaining, nearly in the centre of the old valley. 
The upper surface of this clay was very irregular, and 
here and there, there remained between it and the next 
Boulder clay patches of a Brown clay without stones, agree- 
ing with the Middle Laminated Band which has its place 
between the Basement and the Purple clays at Bridlington. 
Over these patches, and where they were absent, resting 
directly on the "Basement" claj r , in strongly-marked con- 
trast, was another Boulder clay, which was the highest bed 
seen in this exposure, and was continued into the cliff. 
Where seen in the cliff, this bed is of a dark purple 
colour, and when dry has a decidedly greenish tinge. It 
contains a few shells and shell- fragments, and also pieces of 
chalk bored by Pholades and Clionae. 
It forms the base of the cliff from near Speeton to 
Filey, and is also well developed in Cayton Bay, at Scarbro', 
at Eobin Hood's Bay, and at Whitby, — and in fact, in all 
the sections on the coast where the drift is of any depth. 
It is sometimes of great thickness, as near Hunmanby 
Gap in Filey Bay, where it has a height in the cliff of over 
forty feet. 
This Boulder clay, which is clearly the representative of 
the " Purple " clay division south of Flambro', has a very 
uneven upper surface, and in some of the hollows thus formed 
are gravels and the laminated warps which will be again 
referred to. 
Over these, and where they are not found directly over 
the Greenish-Purple cla}^, is another Boulder clay of a well- 
pronounced brown colour, which is also often very thick. In 
cases where it rests directly on the Purple clay, without any 
intercalation (as at Hunmanby Gap, where there is one of 
the clearest examples of this kind), the only distinction 
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