File:The Quarterly journal of the Geological Society of London (13205959223).jpg

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Wicklow, Wexford and
Waterford, and at Bal-
lycotten, Kinsale and
Castletown-bearhaven,in
the county of Cork.
These observations in-
dicate that the subsi-
dence in these islands
was general as regards
the southern portion of
their areas*.
The substratum of
the section described is
the upper portion of the
London clay (1); which
is here very fossiliferous
and dips to the north, or
towards the chalk ridge
at Hilsea. This however
is merely an undulation
of the strata, as all the
lower beds are brought
up in succession before
we arrive at the chalk, and the red plastic clay from
Stamshaw, about a mile to the north, is used for
making the dams water-tight, a purpose for which,
from its weight and tenacity, it is admirably adapted.
Resting on the London clay is the forest (2) with
the roots of trees in situ, at a depth of 1 6^ (in another
place 29) feet below high-water. It dips towards the
north and the inner part of the harbour. Similar re-
mains may also be seen at low-water on the sea-coast
outside the harbour, between South-Sea Castle and
Lump's Fort ; but I had not the means of ascertaining
in either case, to what depth below the level of the
sea the forest extends.
Amongst the peaty matter which is 2 feet thick in
the same stratum with the trees, we find the Lacuna
Montaguei indicating the presence of very shallow salt
water and the growth of the Zostera marina on which
that mollusk feeds. Over this peat is (3) a blue clay
4 feet thick similar to the present estuary mud, and
containing the common shells now found in the
harbour. Above this clay there is a bed of shingle
(4), which seems to indicate that the sea at some
subsequent period had broken into the estuary. One
can well imagine how the low land along this coast
may have been subject to such accidents : indeed if
a violent gale or any other cause should carry away
the narrow neck of shingle connecting Black House

• The Preventive Service men along the coast near Hastings
  

get their principal supply of fire-wood out of the submarine