PALAEOLITHIC INDUSTRIES, CLACTON AND DOVERCOURT. 25
of Swanscombe type. Now the Burnham and Weeley gravels
should normally, and in the absence of some irregularity, be
intermediate in date between the Boyn terrace and the Clacton
channels. They might thus be of nearly the same age as the
lower gravel of Swanscombe.
I have also been fortunate in finding in situ in the bottom
of the middle gravel at Milton St. (or Barnfield Pit), Swanscombe,
a small chopper weighing 12 ounces, in every respect normal for
the Clacton channels.
Upon adding together these various points of evidence I
think we are justified in drawing a tentative conclusion that
the Swanscombe Clactonian (which has been defined as Clactonian
II.) is ancestral to the industry of the Clacton channels.
In following the fortunes of the Clactonian onward in time,
we have first the well-known tortoise-core and Levallois-flake
industry, which is generally, and I think correctly, held to be
contemporary with the Twisted-ovate group. The Clactonian
shows some examples of a primitive, or ancestral, form of the
tortoise-core, and there is undoubtedly some mutual influence
or affinity between the Clactonian and the Tortoise-core
industries. There are also, however, profound differences of
technique between the two. Whereas the normal Clactonian
flake was made by primitive low-angle flaking, with strong
conical bulbs of percussion, resulting in short, thick, clumsy
flakes, the Levallois technique produced broad thin flakes,
worked at a high angle of about 90°, and the bulbs of percussion
were comparatively low, broad swellings. These Levallois flakes
were made from a carefully prepared core, known as the Tortoise-
core. The Levallois is thus a very big advance upon the
Clactonian along this line. The Levallois industry is well repre-
sented in the river-bed gravel at the base of the 50-foot terrace
at the Lion Pit, Grays.
Later than the Twisted-ovate we have in this country a
strongly developed industry which we formerly called Mous-
terian, represented by High Lodge and also by the Stoke Newing-
ton floor, a site that was first described by Worthington Smith
in the Journal of our Club. This industry has no affinity what-
ever with the special technique of the Levallois. Its foundation
is further back in the simple, primitive Clactonian technique.