This submerged forest in the middle of the North Sea has been
described fully, for it raises a host of interesting questions,
that require much more research before we can answer them. A sunken
land-surface 60 feet and more below the sea at high-tide corresponds
very closely with the lowest of the submerged forests met with in our
dock-excavations. But if another bed of peat occurs at a depth of 130
or 140 feet at the Dogger Bank, this would be far below the level
of any recently sunk land-surface yet recognised in Britain. Also,
if the slabs of very modern-looking peat, containing only plants
and insects still living in Britain, come from such a depth, out of
what older deposit can the Pleistocene mammals, such as elephant,
rhinoceros, and hyaena, have been washed?
These questions cannot be answered conclusively without scientific
dredging, to fix the exact positions and depths of the outcrops of
moorlog. When we remember also that beneath a submerged forest at
about the depth of the Dogger Bank there was found at Tilbury, in
the Thames Valley, a human skeleton; and that both human remains and
stone implements have been discovered in similar deposits elsewhere,
we can point to the Dogger Bank as an excellent field for scientific
exploration.
The Dogger Bank once formed the northern edge of a great alluvial
plain, occupying what is now the southern half of the North Sea, and
stretching across to Holland and Denmark. If we go beyond the Dogger
Bank and seek for answers to these questions on the further shore,
we find moorlog washed up abundantly on the coasts of both Holland
and Denmark, and it has evidently been torn off submerged ledges like
those of the Bank. Numerous borings in Holland give us still further
information, for they show that beneath the wide alluvial plain,
which lies close to the level of the sea, there exists a considerable
thickness of modern strata. At Amsterdam, for instance, two beds
of peat are met with well below the sea-level, the upper occurring
at about the level of low-tide, the lower at a depth of about 50
or 60 feet below mean-tide. That is to say, the lowest submerged
land-surface is found in Holland at just about the same depth as it
occurs in England, and probably on the Dogger Bank also.
Below this submerged land-surface at Amsterdam are found marine
clays and sands, which seem to show that the lowest “continental
deposit,” as it is called by Dutch geologists, spread seaward over
the silted-up bed of the North Sea; but no buried land-surfaces have
yet been found below the 60-foot level anywhere in Holland.
This appearance of two distinct and thick peat-beds, underlain,
separated, and overlaid by marine deposits, seems to characterise
great part of the Dutch plain. It points to a long period of
subsidence, broken by two intervals of stationary sea-level, when
peat-mosses flourished and spread far and wide over the flat,
interspersed with shallow lakes, like the Norfolk broads.
Public-domain text, read in full here on John Shaqi.
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