116
THE ESSEX NATURALIST.
It also seems that soils of a heavy character, such as clays, even
if naturally cleared, would have proved too difficult for working
by such elementary means of tillage as these early folk possessed.
In this connection it must be recalled that these prehistoric
people pursued their agricultural activities by means of a hoe-
like hand plough; even the lightest of soils necessitating double
ploughing.
With the knowledge that there can have been very little
artificial clearing of woodland in prehistoric times it seems
not unreasonable to attempt to trace the Forest bounds for the
early periods from a consideration of geological and climatic
conditions alone.
The geology of the county is fairly simple. Essex occupies
an extensive area of the chalk basin of south-eastern England;
the greater part of the basin in Essex being filled by heavy
London Clay. The line of junction between these two rocks
passes north-eastwards across the middle of the county, but
is, however, entirely obscured by a broad tract of chalky Boulder
Clay. This clay belt—a witness of the glacial epochs—extends
some miles north and south of the line of division, leaving only
a small area of chalk country visible to the north-west of Essex.
It is obvious that the soil of the Boulder Clay district will be of
a lighter constitution than that of the London Clay. The
south-eastern termination of this Essex Boulder Clay is fringed
by a narrow zone of light sandy soil of a riverine or glacial
character also trending south-west to north-east. This belt
of light soil is paralleled by a second zone of soils of a similar
constitution occurring along the east coasts of Rochford, Dengie
and Tendring. A third area of light soil is met with in the
small chalky district in the extreme north-west of the county.
Thus, the soils of Essex may be divided into several belts or
zones trending in a south-westerly to north-easterly direction
and varying in texture. A central belt of light soil divides an
area of heavy clay to the south from an equally large area of
lighter clay to the north; both these clay regions being bounded
on their outer fringes by other light soils.
Were the climatic conditions obtaining throughout the
county similar, one could very well postulate alternating bands
of light and heavy woodland, local differences occurring with
the presence of marshy tracts. Such, however, is not the case;