THE DRIFTS OF SOUTH-WESTERN ESSEX. 177
or two Levallois flakes, but these are very rare. I have not been
fortunate in finding any relics in situ in the loess, but I have found
many flakes, scrapers and other implements in the pit. Most
of these are Neolithic and Iron Age, but some stand out from
the majority as something altogether different. These include
the three best gravers I have in my collection from this country,
and their mineral condition is more in accordance with flints
from the loess (where Aurignacian flints might be expected) than
with those from the surface soil; I have no other English imple-
ments (although I have very many gravers) that conform so
closely with Aurignacian technique.
The Holocene, or Recent, Period.—As the reader will have
understood, many of the minor epochs in the foregoing record
were inaugurated by emergence and closed by submergence. In
other words, the effects of these events constitute natural sub-
divisions, even if these may be unequal in length of time. The
Holocene was also inaugurated by emergence of nearly 200 ft.
at about 8,000 or 10,000 B.C. This was the beginning of the
Mesolithic (the mild dry Boreal Period) represented by the lower
peats, some of which occur on the floor of the North Sea.
By the beginning of the Neolithic at about 4,000 B.C. (the cold
damp Atlantic Period) submergence had brought the land down
to little more than 30ft. above that of today. By the close of
the Neolithic at about 1800 B.C. the land stood at practically
its present level, since which time there have been minor fluctua-
tions of emergence and submergence that await fuller investi-
gation.
Larger Constituents of the Gravels.—The vertical
columns give the percentage of the constituents at the following
sites :—1, Westleton ; 2, Brickenden Hill, Herts. ; 3, Jacks'
Hill, Epping Forest. (The foregoing three quoted from Prest-
wich.) 4, the anti-tank ditch S.E. of the "Wake Arms," ; and 5.
S.W. of Ambresbury Banks ; 6, Buckhurst Hill ; 7, Hallsford ;
8, Chigwell Lane (1 to 8 Pebble Gravels) ; 9, Monk Wood,
Epping Forest (Glacial) ; 10, Clacton channel of the Thames-
Medway.