The Chafford Gorges Nature Park has been created in three disused chalk pits that
were actively worked until the 1950s. Lakes in the base of the quarries have been
retained, the surrounding ground has been sympathetically managed to encourage wildlife
(both flora and fauna) and paths have been provided for the public to gain safe access.
A spacious new visitor centre, with a shop selling books, gifts, hot and cold drinks,
sandwiches and snacks, was opened in the spring of 2006. The visitor centre overlooks
Warren Gorge, the largest of the three gorges. A part of the panoramic view from the
visitor centre is shown in the picture on the left.
At 10.30 am on Saturday 28th June seven members met at the visitor's centre for a
geological walk led by Diana Clements. The aim was to look at, and discuss, the
local geology.
Leaving the visitor centre we walked down Merlin Close. On the right hand side there
should have been a good view of our first chalk face. Unfortunately the area is fenced
and trees, planted by the wildlife trust to protect the site, have grown so high that
only limited views of the geology are now possible.
Nevertheless, we did see small solution pipes and flint beds. One of the limited
views is shown in the picture on the right.
From Merlin Close we proceeded to Devonshire Road where the Wouldham Cliffs gave
us an excellent view of the local chalk. Clearly visible was a thin continuous band
of flints that can be see half way up the chalk face in the picture below left.
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This is the Whittaker's 3 inch Flint Band that can also be seen in chalk cliffs at
the Kent coast. The band identifies the chalk as Seaford Chalk of the Santonian
Stage of the Upper Cretaceous dating from about 85 million years ago (Ma)
The entrance to Lion Gorge, being cut through a chalk dividing wall, gave us an
opportunity to get close to the chalk and examine it. It was white, very soft and
frangible with scattered flints; characteristics of the Upper Chalk.
A short walk through Lion Gorge brought us to Philip Sydney Road where a view point
enabled us to look down the gorge that is now a geological Site of Scientific
Interest (SSSI).
Here the chalk has been replaced by Terrace Gravels (Taplow Gravel) from former
levels of the River Thames. A small exposure of gravel can be seen down the left-hand
side of the gorge. Though one may enter the gorge, it is excessively overgrown and
we were content to enjoy the fine view south towards the Thames and North Downs.
The narrow gorge is the site of a tramway that carried chalk from the pits to barges
on the river.
The site was declared a SSSI because of the many mammalian remains it has yielded
and for the evidence of Humans (Levallois artefacts).
From the Philip Sydney Road viewpoint we returned to the visitor centre, via the
steep ramp, for a lunch break. The steep ramp gave us a close-up view of solution
pipes as seen in the picture at the bottom of this page.
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After lunch we visited the Sandmartin Cliffs in Devonshire Road. This site is kept
locked because of the need to avoid disturbance to sandmartins that are summer visitors.
Diana had managed to obtain a key, but this is not possible when the sandmartins
are in residence!
One's first impression is the smooth vertical nature of the face, see picture right.
Do to attempt to climb the exposure and under no circumstances may hammers or
trowels be used on the sand face.
Those of you who are experts at building sandcastles will know that sand size and
water content are the critical issues, and so it is here. Examination of samples
from the base of the sand face showed that the sand particles were extremely fine.
Close up, one could see some interesting burrows in which tubes, of lattice structure,
projected from the sand face (see picture at the foot of this page). In the same area
we saw several wasps, thought to be Chrisis ruddii, a ruby tailed wasp. But
whether these built the burrow, were merely investigating it or, more likely, were
predators of the inhabitants was not clear.
To learn more about these wasps click here
During our tour we saw evidence of cryoturbation, the disturbance of strata by freezing.
During the last ice age the chalk was frozen to a great depth (permafrost). In the
brief, warmer summers the upper metre or so of the chalk thawed and the chalk contracted.
Repeated cycles of freezing, expansion, thawing and contraction caused the chalk to
crumble and form a semi-liquid consistency that has been described as 'like porridge'.
The denser, overlying Thanet Sand sank into the chalk causing the less dense chalk to
rise up around the descending sand, producing the disturbance that we see today.
Deposits of reconstituted chalk, formed by periglacial action during the Pleistocene
period, are known as 'Coombe Deposits'. When these are combined with lumps of chalk
and cemented into a hard mass, the product is known as 'Coombe Rock'.
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Our final visit of the day was to see a number of Sarsens at a spot above the lake
in Grays Gorge (see picture left).
Sarsens are formed at the saturated bottom of sand deposits. It has been suggested
that siliceous material in solution percolates down through the sand and crystalises
out in the lower layers to bond the sand grains into a hard quartzite-like rock
(technically an orthoquartzite). The question was "How did they finish up here?"
It was generally agreed that the rocks must have formed at the base of the Thanet
Sand.
Inspite of being excellent building stone, the rocks were probably not wanted by
the quarrymen who were excavating sand and were therefore cast aside in an unused
part of the quarry.
If the weather is fine, one can easily spend a day in this nature park, studying
the geology and wildlife.
It is recommended that anyone wishing to do so obtain copies of the following documentation:-
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British Geological Survey, England and Wales Sheet 271, Dartford, 1:50,000 Series.
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British Geological Survey, Memoir for the London Area, Sheets E256-7, E270, E271, 2004.
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'Your Guide to Chafford Gorges Nature Park', Published by the Essex Wildlife Trust
This colourful guide contains detailed descriptions of the park, its origins and
wildlife and is available, free of charge, from the park Visitor Centre.
This was not a 'lecture tour' but more in the nature of a 'Socratic dialogue'.
During our rambles, geological features were observed which the members discussed
and tried to explain. Sometimes we agreed, other times we agreed to differ. The
weather was fine, the going was mostly easy and a thoroughly enjoyable time was had by all.
We wish to thank Diana Clements for organising and leading the walk; for
encouraging discussions during the day and for her expert knowledge of the area
and its geology.
Some pictures of the Chafford Gorges Nature Park, taken by Stephen Taylor, are shown below:-
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The profusion of wild flowers at the base of the chalk cliffs in Devonshire Road.
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A wonderfully close view of solution pipes at Lion Gorge, seen from the steep path
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A Skipper butterfly on the reserve. Black antenna tips suggest that this is the Essex variety Thymelicus lineola.
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An unusual burrow protruding from the face of the Sandmartin's Cliff.
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Access and Safety
From junction 30 of the M25, take the A13 eastwards and leave at the second exit
(A1012 southwards). Follow directions to Grays and Chafford Hundred. Cross the
first roundabout, taking the fourth exit into Elizabeth Road. At the second roundabout
turn right into Devonshire Road and almost immediately turn right into Drake road.
Follow Drake road as it bears round to the left, crossing several mimi roundabouts.
After about 1.5 Km the road turns sharply left and the signboard marking the entrance
to the Chafford Gorges Nature Park and Visitor Centre will be seen on the right.
The nature reserve has been developed from the site of three former chalk quarries,
and is now the centre of a large modern housing development. The park is intended
to be a nature reserve open to the public as a local leisure facility. However,
some sensitive areas are locked and access is only possible by permission of the
Essex Wildlife Trust.
Note: Local traffic can present a hazard when walking on, or crossing roads
between the gorges. Young people should be carefully supervised at all times.
Additionally, paths in the former quarries can be uneven and chalk, when wet, is
very slippery.
Do not hammer, or attempt to climb, any of the chalk or sand faces.
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