Marlow Common Clay Pits
Marlow Common is one of 200 commons in the Chilterns which have been shaped by
centuries of local history. As you walk in this lovely part of Buckinghamshire today it is
difficult to imagine a time when it was not grass and woodland. However, the rocks beneath
your feet tell an amazing story of Marlow Common over the past 80 million years. It is a
story that takes us from flooding by a shallow chalky sea to a tropical landscape with
waterlogged clay soils, and finally to the frozen wastes of the Ice Age. It was these extremes
in climate that laid down the geological layers, but it was local people who finally shaped it
into what we see today.
The geological story 1. Marlow under a tropical climate
Chalk
The Chalk is pure limestone made from tiny skeletons of algae. They settled out in a tropical
sea during a massive global warming. Climate started to warm dramatically at around 95
million years ago. This event was to continue for the next 30 million years, finally ending 65
million years ago. During this time the world became much hotter – resulting in a global
average temperature of about 30 degrees (compared to 15 degrees today). As climate
warmed, ice melted, and sea level rose. As the world warmed further the water in the oceans
expanded and the result was a very large proportion of all land on Earth being flooded by
shallow seas. This of course included the whole of what is now England, including Marlow
Common. These seas were teeming with life and some
of these animals are preserved as fossils within the
chalk and inside flint nodules – both have been found
nearby and on the common.
A sea urchin preserved in flint
A sponge preserved in Chalk, one of the
most common fossils
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Clay-with-flint
After 30 million years of global warming, the Earth gradually returned to more normal
temperatures from 65 million years ago. This resulted in sea level falling which exposed the
whole of England as land again, including Buckinghamshire, which was exposed as a flat
ancient sea bed. Rain dissolved huge quantities of chalk resulting in a residual layer on top
composed of clay and flints – as neither of these dissolve in rainwater.
Clay-with-flints – the result of 20 million years of dissolved Chalk.
Reading Formation clays
From 60 to 50 million years ago the Chalk seas had retreated and Bucks was a hot, tropical
landscape. The flat landscape produced waterlogged soils resulting in the quality clays later
used for the local brick and pottery industry. The Reading Formation clays are not shown in
the geological section as they are no longer present in sufficient quantity to map. They were
excavated during the 19th to earliest 20th century. However, the first geological map to be
produced was later in the 20th century and so they were never seen on Marlow Common by
geologists. Nonetheless, hints of where they were, how they were excavated and how much
clay was there, can be seen in clues remaining in the landscape today.
We know very little about the geological history in Marlow after 50 million years ago, as
erosion has removed much of the evidence. However, we know from elsewhere that
Buckinghamshire remained very flat during most of this time, until the start of the Ice Age
2.6 million years ago. It was during the Ice Age that the Chiltern Hills were formed and the
mighty Thames was born and cut down into the valley we know today.
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The rock sequence at Marlow
Common. Oldest rocks at the
bottom, youngest on the top.
A section through the rock layers from the Hambleden Valley to the Thames in Marlow,
showing the landscape and the different layers under each area. The Ice Age deposits
are like icing on the main ‘rock cake’.
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The geological story 2. Marlow as tundra on the edge of the ice
Sands and gravels of the River Thames
Gravels are obvious in some parts of the Common – their presence indicated by acid-loving
plants such as heather, gorse and oak. The rounded pebbles found in the footpaths show they
are from a river. The pebbles are mostly flint, but whitish quartz pebbles may be found along
with duller, very round, pale brown sandstone. These pebbles are part of the Gerrards Cross
Gravels and record a time when the ancient River Thames flowed here before cutting down to
its present level in Marlow. The Thames cut down and left a gravel terrace during each big
freeze when ice advanced towards and sometimes over England. This down-cutting is
preserved in ten stages for the whole Thames valley and three of these events are visible from
Marlow Common and down the hill towards Marlow. The geological section shows Winter
Hill and then Taplow, and finally Shepperton Gravels each successively at lower levels - and
each successively younger. The youngest sediment of all is the modern-day alluvium in the
river. Rivers cut down incrementally this way as a
result of sea level falling when water is locked up
in ice sheets. Sea level is the ‘base’ level to which
all rivers flow, and if it lowers, so the river entry
point is lowered. This has a knock-on effect
upstream. The result is the old level left high in
the slope or cliff face as a terrace with the old
sands and gravels high and dry.
Thames gravels showing the direction of water
flow as inclined lines.
Dry valleys
While major dry valleys were being cut to the
west (as the Hambleden Valley) and to the east
(the Wye valley) Marlow Common was within a
smaller catchment area draining down to the newly forming Thames river. The steeper slopes
of Lords Wood were cut by melting snow and ice flowing over frozen ground (tundra).
Dry valleys only form during cold phases when the ground is frozen – in other words, in a
tundra environment. Each time the Chilterns became tundra the pores of the Chalk were
blocked with ice and so when the ice and snow started to melt, the result is water forced to
flow over the frozen ground. This cuts a ‘V’ shaped river valley which is so distinctive of
water flow, but the dry valleys today look flatter as much sediment and debris has collected at
the bottom.
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Brick and tile industry on Marlow Common
Evidence for this past industry comes in the form of numerous pits and sinuous depressions
as well as house names such as Kiln Cottage and the Old Kiln House. The clay used was
from the Reading Formation, and the products were mostly bricks and tiles. There was also a
quality terracotta ware produced, which may be seen at Monks Corner as a long frieze panel.
This was called Medmenham Ware and was produced by the sculptor Conrad Dressler
between 1898 to 1905. Dressler was born in London in 1856 and became the design manager
of the works. The pottery and kiln was owned by Robert Hudson, who made his fortune as a
soap magnate. He bought Medmenham Abbey, arranged for its restoration and then went on
to design and build a number of estate houses such as Westfield Cottages, Medmenham. The
pottery was built in order to support and encourage rural crafts – as Hudson was an admirer
of the Arts and Crafts ideas of William Morris. The company advertised the fact that they
were proud to use local materials and employ village work people. The products were high
quality, handmade or moulded forms and bespoke to order. Their advertising lists the types
and the top quality raised tile was priced at an average of 30 shillings per yard. Architects
soon made use of this quality product for prestigious buildings such as the Sunlight Chambers
in Dublin and the Law Society Hall in London. Tiles are on display in the V&A Museum in
London. Local examples may be found for instance as a frieze panel at Jerome Cottage
(Monks Corner). The name of the house is notable as the home of Jerome K. Jerome, author
of Three men in a boat c. 1910 to 1920.
Medmenham Ware frieze panel at Monks Corner.
The 1898 map of the common shows the old clay pits along with the two brick kilns in
operation at that time. The common would have been an unpleasant place to live at that time.
The area would be taken up with extraction pits and piles of clay exposed for weathering.
There would be ‘puddling’ areas for processing the clay, vast drying areas for moulded
bricks, and during the firing days, the air would be thick with smoke.
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In addition to the main extraction pits there were a number of smaller pits. These were never
mapped as they were short-lived and very small. A walk around the common today will
reveal many undulations, rounded depressions and sinuous trenches where small pockets
were ‘chased’ by small work teams for this valuable clay.
A deep sinuous excavation removing pockets of brick-making clay.
Looking at the total area of pits from map and modern evidence it can be calculated that
Marlow Common’s production from its own clay source must have been around 150,000
bricks or terracotta products. The bricks (some called the ‘Marlow blues’) may be seen
locally on and near the common and in Marlow town centre. However, the brickyard
undoubtedly received clay from neighbouring extraction areas, and so its total production
would have been much larger.
The following pages show extracts from the historic maps showing how Marlow Common
has changed since 1876.
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Marlow Common on the 1876 map. The first brickworks was already built and
operational on the common. Brick suppliers in the area of this date (listed in Kelly’s
directory) would imply the brickyard was run by Allum’s, Corby’s or Hickman’s – all
brick and tile merchants with offices in the High Street, Marlow. (The grid scale is 100
m intervals).
The 1898 map of Marlow Common showing the location of the largest pits and the two
brickworks at that time. Clay extracted during this time was supplying the
Medmenham Pottery works from 1898 to 1905. (The grid scale is at 100 m intervals)
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The 1921 Map shows the brickyards have gone and the pit to the north is the ‘Old Clay
Pit’ whilst the Monks Corner pit has been landscaped into the garden feature of today.
The old kiln was standing in the 1930s as the photograph below shows. The buildings
attached to it are the moulding area and drying shed. Kiln Cottage is near the spot today.
The old kiln on Marlow Common during the 1930s, a small but vital source of local
income. Photograph courtesy of Janet Smith.
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A walk around the common today will reveal a little of this history – the clues are beneath
your feet. The Chalk, river gravels and Clay-with-flint are seen in the paths and soils. The
soils themselves are made from the geology lying beneath – sandy over the river deposits and
clayey over the Clay-with-flints. In turn the soils are intimately related to the plants that grow
on them. This link of rocks into soils into nature is all around you on any stroll through the
common. Nature moved in when people moved industry out. Those people that once worked
in the brick industries have long gone, but their mark is left – in the form of empty pits and
the quality bricks of local houses.
Text provided by Dr Jill Eyers (www.chilternarchaeology.com) for the Chiltern Society
and Marlow Common North with funding from the Heritage Lottery Fund. The
interpretive work formed part of the Chiltern Conservation Board’s Chilterns
Commons Project.
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