314 G. W. LAMPLUGH ON SHELLY PATCHES IN THE 
from a strip of beach about 120 yards long hy 30 wide, stretching 
from the base of the sea defences, near high-water mark, to a little 
below the level of half-tide. 
The beds exposed formed part of the lowest recognized division 
in the glacial series of Yorkshire, that to which the term Basement 
Boulder-clay has been applied*. Though the sea defences already 
alluded to completely mask the cliff immediately abutting, there is, 
at the time of writing, a wide breach in the terraced wall just north 
of the groyne, as shown on the ground-plan ; and here the Basement- 
clay is seen to rise to a height-of 15 feet above the level of the 
beach, sinking gently northward. And as there is no reason to infer 
a sudden change in its level, we may estimate the plane exposed on 
the shore to be at an average depth of about 20 feet from the top 
of the clay. 
In the section just mentioned, the Basement Boulder-clay is over- 
lain by the Purple Boulder-clay, with the occasional intervention of 
a little sand or gravel. The Laminated Clay, which is so well de- 
veloped between them both north and south of the town, is here 
absent. 
The Boulder-clay in the exposure on the beach was of a dark 
greenish-blue colour, and generally hard and sandy in texture. It 
contained a few angular and subangular boulders, none very large 
in size, and many smaller pebbles, generally well rounded and some- 
times scratched. These included an immense variety of rocks of 
various ages, igneous and metamorphic rocks being especially abun- 
dant. I made a collection of them, hoping that at some future time 
their identification might be possible. Fragments and occasional 
valves of marine shells occurred in plenty in the clay. 
The Boulder-clay also included in it many crushed masses of sand, 
and sandy gravel and clay, these forming, indeed, a large proportion, 
nearly one third, of its bulk. These masses, which generally con- 
tained marine remains, were of all sizes and shapes, some, as seen 
on the beach in horizontal section, appearing more or less round and 
coherent, others occurring as long, thin, sometimes intermittent, 
streaks between slabs of Boulder-clay, with every form between 
these extremes. In like manner the lithological character of the 
masses varied ; some consisted of clay alone—blue, brown, or leaden- 
hued; others of clay with the admixture of sand; others of gravel 
and sand with little clay. One of the largest of the masses, that 
marked B on the plan, consisted in part of roughish gravel, the 
larger pebbles being about the size of a small orange; these were 
thoroughly water-worn and rounded, and I found amongst them 
the following rocks:—black flint, sometimes with green coating; 
red flint; nodules, some apparently Neocomian, others probably 
Liassic ; yellow claystone ; several varieties of basalt ; brown quart- 
zite ; dark volcanic ash, and other igneous rocks unknown to me. 
* For cliff-sections and general account of glacial and postglacial beds in 
the neighbourhood, see my papers on “Glacial Sections near Bridlington” im 
‘Proceedings of the Yorkshire Geological and Polytechnic Society,’ vol. vi. 
pt. iv. p. 383 (1881); vol. viii. pt. i. p. 27 (1882), and pt. ii. p. 240 (1883). 
