|Coastal Erosion special:
Eastern England - April 2009
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saw me travelling over to Essex following the death, after a longish
illness, of my dear Brother-in-law, Martin Waite. To say that he was a
man of many talents would be an understatement, and I shall simply say
that I will evermore miss going for a pint and a good natter with him
to the Black Buoy, his favourite pub in the small estuary-side town of
Wivenhoe, where they lived together for many happy years.
camera came along too, of course, as in between other things there were
constitutional walks that needed to be taken, including an unexpected
opportunity to visit somewhere new and witness at first hand the rapid
erosion of the Eastern coastline of the UK. More on that below.
itself is a beautiful, interesting old shipbuilding town with a great
waterfront, some of which retains its old and interesting feeling:
...with the more modern
aspect of the Colne Barrage downstream, and the gravel and sand-pits:
....and upstream, the "tidier" bit, which
seems far less interesting to me!
The opportunity to visit Walton-on-the-Naze on April 7th coincided with
a clearing sky and, in due course, excellent photographic light. North
of the seaside town, The Naze is a cliff-bounded spit of land that
points north, petering out in the mass of tidal creeks south of
Harwich. The cliffs themselves face the North Sea:
cliffs and foreshore at The Naze consist of sticky, soft grey London
capped with the brightly-coloured Red Crag, a sandy deposit rich in
marine shells. A quick look back through time might help here in order
to visualise what was going on.
The London Clay was deposited in Eocene times, about 50 million years
ago, or 15 million years after the dinosaurs became extinct. The
environmental theme was one of an extremely warm climate and no polar
ice-caps, and high sea-levels that covered a lot of SE England.
During the remainder of the Cenozoic era (consisting, oldest first, of
the Palaeocene, Eocene, Oligocene, Miocene, Pliocene, Pleistocene and
Holocene epochs), the global climate gradually cooled, culminating in
the great ice-ages of the Pleistocene, the last one of which only ended
11,700 years ago at the start of the Holocene epoch, in which we exist.
With the cooling there came falls in sea-level, but the shelly fossils
show that the Red Crag, belonging to the Piacenzian (formerly
Waltonian) stage of the Pliocene epoch (1.8-3 million years old) was
deposited under marine conditions. The Red Crag presents, to the
geologist, evidence of a shallowing-upward sequence from subtidal
marine sands to intertidal sand flat deposition.Indeed, these strata
trace the climatic deterioration that led finally to the onset of
glaciation in the British Isles. Along the cliff-tops there is direct
evidence for the bitter cold that followed, in the form of structures
attributed to permafrost.
The image below shows strong cross-bedding, tilted structures that are
deposits from bedforms, such as ripples or dunes: they indicate to the
geologist that the depositional environment contained a flowing fluid
(in most cases, water or wind). Thus, cross-bedding where the
sediments are deposited by water is indicative of currents at work -
such as rivers, estuarine and tidal/subtidal environments.
The question of whether this environment was marine or non-marine is
neatly answered by the presence of bands of fossil sea-shells:
The commonest of them is
the cockle, Glycimeris, still around today. Their iron-stained shells
wash out of the fairly soft Red Crag and end up on the beach, mixed up
with modern seashells, shingle and the shark teeth, from the London
Clay, that attract fossil-hunters daily:
But, for anybody with an
interest in climate change today, it is the incredible erosion that
The Naze Tower was built in 1720, as a navigational aid. They sited it
about a kilometre inland: it is now less than 50m from the edge of the
cliffs! Pill-boxes from World War 2 stick up out of the sea, uncovering
as the tide goes out. These combine to illustrate just how rapid the
...it is estimated to average 2m per year.
The image below is of the same landslipped area, looking down and R to
the vantage point where I shot the image above...
Landslipping takes several
forms. A common feature is deep rotational slip, where sliding occurs
at the watery junction between the permeable Red Crag and the
impermeable London Clay below. The image below shows the surface
expression of this process, with sections of land slumped, tilted
backwards and separated by deep open fissures:
Rainwater causes the slipped material to
liquefy, resulting in mudflows that sprawl on down to the beach, but
storms quickly erode this material and spread it up the beach, leaving
further cliff ready to collapse:
The surfaces of the mudflows become temporarily colonised by plants
such as Coltsfoot:
Evidence for lost land - look at this water-pipe!
- towards Walton - the coast is relatively stable, thanks to the
concrete sea-defences and groynes. But these, too, are eroding: it is
just that the rate is much, much slower. But can the entire coast be
protected in this way in the face of the land's natural sinking and
sea-level rise due to climate change? This is something that is a major
topic of debate in the east of England. Can Nature ever be completely
stopped? That is the question.
is easy to imagine how the already impressive 2m/year erosion rate will
accelerate if some of the projected sea-level rises generated by
climate models do occur as forecast. I left Walton-on-the-Naze
wondering just what it might look like in a hundred years'
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