THE DRIFTS OF SOUTH-WESTERN ESSEX. 159
along Lodge Road, and thence along the Epping New Road
to the 5-cross roads at the "Wake Arms." Another runs for
1/4 mile or more S.E. from the 5-cross roads, and then swings N.
along "The Ditches" to the S.W. corner of Ambresbury Banks,
and from thence across the Epping New Road to the Warren.
Sandy Pebble Gravel is seen thrown into festoons, about 6 or 8
feet deep, like miniature synclines, some of which retain their
original stratification in the lower part.
The ditches surround and partly cross the area of the former
Jacks Hill gravel diggings where Prestwich recorded 10 per cent
of chert.
In one case I obtained one piece of Lower Greensand chert
in a detailed examination of 400 stones from the lower stratified
part of the gravel. Near Copt Hall I found a number of pieces
of chert on a very small area of the dump, among comparatively
few other stones, but failed to get another piece within 100 yards.
This may well have equalled the 10 per cent record, but I could
not find any satisfactory cherty gravel in place to give a reliable
frequency.
In the greater part of the local Pebble Gravel chert is very
scarce, so there appear to be different gravels over the same area
and within the same range of levels.
The festoons of true Pebble Gravel contain no trace of
Glacial material.
Laindon Hills [Wooldridge, 1927, 2].—The gravels capping
these hills (between 370 and 385 O.D.) are an important outlier
of the early Pebble Gravel group, and they contain "Cretaceous
stones" in abundance. There is another outlier 7 or 8 miles
to the N. at Stock (310 to 320 O.D.), which also belongs to the
same group.
The Warley Gravel (300 to 360 O.D.) [Wooldridge,
1927, 2 ; Dines, 1925].—This group of pebble gravels caps the
Bagshot outliers in the neighbourhoods of Warley, Thorndon
Park, Billericay, Navestock, Kelvedon Hatch and Ongar Park
Wood. Some 20 or 30 per cent of the flint pebbles are of a
long oval, or cylindrical form : "Cretaceous stones" are present,
but rare. In sharp contrast, the Bagshot pebble beds which
underlie these gravels are more sandy and contain neither the
cylindrical pebbles nor the "Cretaceous stones." It is worth
noting that cylindrical pebbles are characteristic of the Blackheath
Beds of Kent.
Thus, the constituents of the Warley gravel indicate that it
is a local variety of the Pliocene Pebble Gravel group. But, as
we see it to-day, it is essentially a "static" deposit.