GLACIAL STRATIGRAPHY OF WEST ESSEX 325
change in moisture contents, Atterberg limits and plasticity
indices reflecting the increasing contribution of the underlying
London Clay to the lithological constitution of the till matrix.
Slight drops in the LL and PI at Coopersale Common (68-691/2) may
result from the admixture of local "head" and Pebble Gravel
material with the boulder clay. More importantly, the LL figures
indicate that the textural and mineralogical composition of the
Hanningfield Tills does not diverge significantly from the regional
trend of lithological change within the Springfield Till. The
liquidity indices do not demonstrate any comparable trend in
compaction, but it may be remarked that the adjacent Hanning-
field (68-691/2) and Springfield (691/2-771/2) sections are of virtually
identical consolidations, while those of the Hanningfield (78-91)
and Springfield (91-100) tills are certainly of the same order of
magnitude. The boulder clays from Coopersale Common (68) to
Pincey Brook (100) would all seem therefore to belong to a single,