View report page

26
long-term planning of industry and the establishment of viable
residential areas in the Borough (as in the case of "Thamesmead")
hazardous undertakings.
SUPERFICIAL GEOLOGY
Geological formations occurring in the London Borough of
Greenwich are of two groups, namely, the "superficial deposits"
and the "solid formations". These are given below, seriatim, in
descending order and while this holds good for the area as a whole,
the complete sequence is not always met with for superficial
deposits may be non-existent, local arching of strata and subsequent
denudation of the higher parts may have brought to the surface
lower members of the succession and, in other cases, a stratum of
the sequence may be entirely absent. Where maximum and minimum
depths are stated, this implies a true variation of the thickness
of the beds in question, and, with the exception of the superficial
deposits, is not to be ascribed to thinning due to erosion.
Superficial deposits in the Borough are distributed over the
surface of the "solid formations" and may be considered as being
of (a) "made" ground, (b) alluvium, and (c) gravel, the latter
deposit being of the Pleistocene or "drift" series. At some places
these deposits fill deep hollows in the surface of the "solid" attaining
a maximum thickness of about 70 feet and at others are
arranged as banks. More usually they form spreads of comparatively
uniform thickness, or remain caps to the higher ground.
Situated below these are the "solid" Eocene formations of Claygate,
London, Blackheath and Woolwich and Reading beds followed
by that of Thanet Sand. Underlying the whole Eocene strata
is the Chalk or Cretaceous formation.
Superficial Deposits
Made—Made ground, consisting of artificial accumulations of
debris and dumped materials from excavations have been spread
over a number of areas of the district especially where the material
has been used to raise the surface level of alluvial areas to reduce
flooding in times of exceptionally high tides and heavy rainfall.
Alluvium—Such a term is applied to the deposits up to 30 feet
in depth forming the low-lying areas bordering the Thames and its
tributaries. Originally marshland, these areas are still liable to
flood should the river overflow its banks except where artificial
means of protection have been adopted.
Consisting of alternations of mud or silt, clay, shell marl, peat,
sand and gravel, any or all of which may be present, the deposits
may lie directly on "solid formations" or on banks of "river