42 
tom, he says “ that at the present moment it is filled up 
nearly to the surface with an agglomeration of rounded 
lumps of clay more or less compacted together. The clay 
boulders, for such they are, vary in size from 18 inches on 
the longer axes to the size of a bean, and from a spherical 
to an ellipsoid figure/’ 
“ We have not far to seek for their origin, as a visit to the 
lower edge of the peat frayed into a sort of a subtidal cliff 
or series of cliffs by the encroachments of the sea, shows a 
deposit of similar clay boulders at its base. In the neigh- 
bourhood of the beach the river Alt, meandering over the 
shore, has made inroads on the post-glacial deposits which 
compose the substratum, forming a subtidal river cliff of 
blue clay at its western margin. Lumps of this clay under- 
mined by the currents fall, break up into pieces, and get 
rolled into boulders by the action of the tide. The trench 
has formed a sort of trap for catching and retaining them. 
The clay boulders are in contact, and become in the trench 
compacted together into one solid mass, so that if it were 
converted into rock its structure would show in some cases 
distinct argillaceous boulders in a sandy argillaceous matrix, 
and in others an imperceptible shading of the boulder 
nucleus into the matrix.” 
The boulders of clay found at Moss Bank have in all 
probability been formed in a similar manner to those de- 
scribed by Mr Reade, as they are found in a hollow in the 
sand of a basin-shape in vertical section, which would be 
somewhat like the trench described by him, having fallen 
from an old cliff of till and been rolled by water into the 
place where they are now found. In the sand are sometimes 
found minute fragments of shells, but in such a state that it 
is impossible to determine what they are. 
