168 
LAMPLUGH : GLACIAL BEDS. 
Nevertheless, there is evidence which convinces me that 
long and wide-spread breaks have occurred in the forces 
which brought together these clays. 
At the base of the drift at Speeton is a band of very fine 
earthy chalk-rubble, resembling rain-wash. This bed is seen 
on both sides of the gully known as Speeton Gap, and may 
be traced from the Chalk Escarpment to the point where the 
Secondary (Neocomian and Kimmeridge) clays sink to the 
sea-level in New Closes Cliff, a distance of about three- 
quarters of a mile ; and in an interesting exposure on the 
beach near Reighton Gap, nearly a mile further north, which 
I recently had an opportunity to examine, it still held its 
place between the drift and the Upper Kimmeridge Shale, 
which here formed the underlying bed. 
At Speeton Gap this chalky rubble has a thickness of 
about ten feet ; but in the exposure on the beach at Reighton 
it was much thinner, and probably dies out a little further to 
the north. 
This bed may be of the same age as an exactly similar 
rubble which is seen on most of the preglacial chalk valley- 
slopes south of Flambro', and which holds a like position 
between the drifts and the underlying secondary strata. 
Closely associated with this chalky rubble at Speeton is 
the Sand-bed containing a few species of shore- shells, to 
which Professor Phillips first drew attention,* and which was 
believed by him to belong to the drift series. 
I have lately seen, however, that it is distinctly older 
than any boulder clay in Filey Bay ; and as a representative 
of the oldest Yorkshire clay will presently be shown to occur 
here, it follows that it is older than any Yorkshire glacial 
deposit. 
This shell-bed is first seen in the cliff a few hundred yards 
* " Geology of Yorkshire," 3rd ed., p. 101. 
