GEOLOGICAL AND PREHISTORIC TRAPS.
17
Although the boulders of the "spread" are naturally of
mixed origin, the greater number, particularly the larger ones,
are fresh chalk flint, many being the familiar Paramoudras,
recently washed out of the Chalk by the sea. As these heavy
flint boulders are piled up by the waves to form this remarkable
"spread," the force of their impact one against another causes
the detachment of the "Cromerian" flakes, which are found
among them.
The contrast between the two interpretations of the
Cromerian site is shown in the figure. The diagram A represents
that of wishful thinking, or in the homely phrase, building
castles-in-Spain; the big flints of the Cromer spread with their
associated flakes rest exclusively, it is supposed, upon the Chalk
("Ch.") and are immediately overlaid by the Forest Bed ("F. B.")
concealed by the sand of the upper beach.
The second diagram, B, shows the Cromer spread as being
the surface of a modern marine bank of sand and boulders. Under
this is the fossiliferous Weybourne Crag (Wb.)2, and beneath
that again the true Stone-bed resting on Chalk. The outcrop
of the Stone-bed on the fore-shore, seen at the foot of the broken
line in the diagram, is only visible at spring tides, as it lies below
the level of low water of neap tides. The top of the bank rises
to about 8 feet higher.3
It should be noted that in both the diagrams, A and B, the
slope of the beach is abbreviated, or cut off, by a broken line,
in order to show the essential conditions within a reasonable
space.
Finally, I would say that the detailed study of "Cromerian"
flaking throws much light upon one aspect of natural flaking,
namely that caused, not by pressure, but by the concussion, or
forceful impact, of one stone against another.
Present-Day Patination of Flint.—Another trap,
particularly associated with the "Cromerian" flakes, is the
natural supposition that a deep ochreous patination must
indicate a profound antiquity. I was formerly a victim of this
2 I have given the collection of shells to the British Museum; they have been kindly
examined by Dr. Cox, but space forbids the inclusion of detailed lists of species on this
occasion.
3 It is probable that the Forest Bed overlies the Crag nearer the cliff, but this has not been
proved.