HOME

TheInfoList



OR:

Brickearth is a term originally used to describe
superficial Superficial may refer to: *Superficial anatomy, is the study of the external features of the body *Superficiality, the discourses in philosophy regarding social relation * Superficial charm, the tendency to be smooth, engaging, charming, slick and ...
windblown deposits found in southern
England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It is located on the island of Great Britain, of which it covers about 62%, and List of islands of England, more than 100 smaller adjacent islands. It ...
. The term has been employed in English-speaking regions to describe similar deposits. Brickearths are
periglacial Periglaciation (adjective: "periglacial", referring to places at the edges of glacial areas) describes geomorphic processes that result from seasonal thawing and freezing, very often in areas of permafrost. The meltwater may refreeze in ice wedg ...
loess A loess (, ; from ) is a clastic rock, clastic, predominantly silt-sized sediment that is formed by the accumulation of wind-blown dust. Ten percent of Earth's land area is covered by loesses or similar deposition (geology), deposits. A loess ...
, a wind-blown dust deposited under extremely cold, dry, peri- or postglacial conditions. The name arises from its early use in making house
brick A brick is a type of construction material used to build walls, pavements and other elements in masonry construction. Properly, the term ''brick'' denotes a unit primarily composed of clay. But is now also used informally to denote building un ...
s, its composition being suitable for brick-making without additional material being added; unlike clay, its bricks can be hardened (fused) at lower temperatures, including in wood-fired kilns. The brickearth is normally represented on 1:50,000 solid and drift edition geological maps. In the
Thames The River Thames ( ), known alternatively in parts as the River Isis, is a river that flows through southern England including London. At , it is the longest river entirely in England and the second-longest in the United Kingdom, after th ...
valley, in broad patches brickearth overlies
fluvial terrace Fluvial terraces are elongated Terrace (geology), terraces that flank the sides of floodplains and fluvial valleys all over the world. They consist of a relatively level strip of land, called a "tread", separated from either an adjacent floodplai ...
gravel; it has been reclassified on later maps as the " Langley Silt Complex".


Description

Brickearth is a superficial deposit of homogeneous
loam Loam (in geology and soil science) is soil composed mostly of sand (particle size > ), silt (particle size > ), and a smaller amount of clay (particle size < ). By weight, its mineral composition is about 40–40–20% concentration of sand–si ...
or
silt Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz. Silt may occur as a soil (often mixed with sand or clay) or as sediment mixed in suspension (chemistry), suspension with water. Silt usually ...
Kent Minerals Subject Plan, BrickEarth Written Statement
May 1986, Kent County Council Planning Department. Accessed April 2012
deposited during the
Pleistocene The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...
geological period. Brickearth typically occurs in discontinuous spreads, across southern England and South Wales, south of a line from Pembroke in the west to Essex in the east in depths of up to a metre. Commercially useful deposits of about 2m to 4m thick are present in Kent, Hertfordshire and Hampshire, overlying
chalk Chalk is a soft, white, porous, sedimentary carbonate rock. It is a form of limestone composed of the mineral calcite and originally formed deep under the sea by the compression of microscopic plankton that had settled to the sea floor. Ch ...
, Thanet Beds or
London Clay The London Clay Formation is a Sediment#Shores and shallow seas, marine formation (geology), geological formation of Ypresian (early Eocene Epoch, c. 54-50 million years ago) age which outcrop, crops out in the southeast of England. The London C ...
. The original deposition of the sediments occurred under cold climates where
fluvial A river is a natural stream of fresh water that flows on land or inside caves towards another body of water at a lower elevation, such as an ocean, lake, or another river. A river may run dry before reaching the end of its course if it ru ...
out-wash sediments from glaciers were subject to windy dry periods. The exposed finer-grained sediments were picked up and transported by the wind and were deposited wherever the wind strength decreased. There are extensive brickearth deposits in
Kent Kent is a Ceremonial counties of England, ceremonial county in South East England. It is bordered by Essex across the Thames Estuary to the north, the Strait of Dover to the south-east, East Sussex to the south-west, Surrey to the west, and Gr ...
, particularly on the
North Downs The North Downs are a ridge of chalk hills in south east England that stretch from Farnham in Surrey to the White Cliffs of Dover in Kent. Much of the North Downs comprises two Area of Outstanding Natural Beauty, Areas of Outstanding Natural Be ...
dip slope and on the
Hoo peninsula The Hoo Peninsula is a peninsula in Kent, England, separating the estuaries of the rivers Thames and Medway. It is dominated by a line of chalk, clay and sand hills, surrounded by an extensive area of marshland composed of alluvial silt. The ...
, sections of the
Medway Medway is a Unitary authorities of England, unitary authority area with Borough status in the United Kingdom, borough status in the ceremonial county of Kent in South East England. It was formed in 1998 by merging the boroughs of City of Roche ...
and Stour valleys. Its mineral content is critical to its applicability in
brickmaking A brick is a type of construction material used to build walls, pavements and other elements in masonry construction. Properly, the term ''brick'' denotes a unit primarily composed of clay. But is now also used informally to denote building un ...
and requires precise proportions of
chalk Chalk is a soft, white, porous, sedimentary carbonate rock. It is a form of limestone composed of the mineral calcite and originally formed deep under the sea by the compression of microscopic plankton that had settled to the sea floor. Ch ...
,
clay Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolinite, ). Most pure clay minerals are white or light-coloured, but natural clays show a variety of colours from impuriti ...
, and
iron Iron is a chemical element; it has symbol Fe () and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, forming much of Earth's o ...
.Loessic Brickearth Map
at Physical Properties and Behaviour of UK Rocks and Soils. British Geological Survey, National Environmental Research Council. Accessed April 2012
Brickearth requires little or no admixture of other materials to render it suitable for the manufacture of ' stock bricks'. In 1986, four active stock brick works were in Kent: at
Otterham Quay Upchurch is a village and civil parish in the Swale district of Kent, England. It is situated about north of the A2 road, between Rainham and Sittingbourne. History It is probable that, although today the land is low-lying and marshy, it ...
, Funton,
Murston Murston is a suburb of Sittingbourne, in the Borough of Swale, Swale district, in the county of Kent, England. It is about 1 mile north-east of central Sittingbourne, on the east bank of the Milton Creek. History According to Edward Hasted in 179 ...
and
Ospringe Ospringe is a village and area of Faversham in the English county of Kent. It is also the name of a civil parish, which since 1935 has not included the village of Ospringe. The village lies on the Roman road Watling Street (nowadays the A2 ...
. The brickearth gives rise to rich and fertile soils which have been exploited for agriculture.Tendring Essex Geodiversity poster
Peter Allen, Gerald Lucy, Teresa O’Connor, David Bridgland, William George, Adrian Gascoyne, Adrian Knowles, Tom White. Quaternary Research Association, Geo Essex . Accessed April 2012
It is prone to rapid 'collapse' settlement when saturated with water and does not provide a firm foundation for buildings. In
Chichester Chichester ( ) is a City status in the United Kingdom, cathedral city and civil parish in the Chichester District, Chichester district of West Sussex, England.OS Explorer map 120: Chichester, South Harting and Selsey Scale: 1:25 000. Publisher ...
, the brickearth is a flint-rich brown silty clay up to five metres thick, which occurs on the coastal plain. The brickearth is unfossiliferous but occasionally yields man-made flint implements.Pleistocene
Chichester Museum website. Accessed April 2012
When used for
brick A brick is a type of construction material used to build walls, pavements and other elements in masonry construction. Properly, the term ''brick'' denotes a unit primarily composed of clay. But is now also used informally to denote building un ...
making, it was often dug from small temporary holes and baked into bricks on the spot in
brick clamp :''"Brick clamp" also refers to a device (usually powered) to lift quantities of bricks.'' A brick clamp is a traditional method of Brick#Methods of manufacture, baking bricks, done by stacking unbaked bricks with fuel under or among them, then ...
s, and used for building nearby. The hole often remained and became a
pond A pond is a small, still, land-based body of water formed by pooling inside a depression (geology), depression, either naturally or artificiality, artificially. A pond is smaller than a lake and there are no official criteria distinguishing ...
.


References


The engineering properties and behaviour of the brickearth of south Essex
K. J. Northmore, F. G. Bell and M. G. Culshaw, doi: 10.1144/GSL.QJEGH.1996.029.P2.04 May 1996 Quarterly Journal of Engineering Geology and Hydrogeology, 29, 147-161. {{Soil type Sediments Types of soil