![Turkey Brook and Turkey Street - geograph](https://upload.wikimedia.org/wikipedia/commons/d/d5/Turkey_Brook_and_Turkey_Street_-_geograph.org.uk_-_9979.jpg)
Turkey Brook is a river in the northern outskirts of London. It rises in
Potters Bar
Potters Bar is a town in Hertfordshire, England,in the historic County of Middlesex Hertsmere Borough Council – Community Strategy First Review (PDF) north of central London. In 2011, it had a population of 21,882. In 2022 the population was ...
, Hertfordshire, and flows broadly eastwards to merge with the
River Lea Navigation
The Lee Navigation is a canalised river incorporating the River Lea (also called the River Lee along the sections that are navigable). It flows from Hertford Castle Weir to the River Thames at Bow Creek; its first lock is Hertford Lock and i ...
near
Enfield Lock
Enfield Lock is an area in the London Borough of Enfield, north London. It is approximately located east of the Hertford Road between Turkey Street and the Holmesdale Tunnel overpass, and extends to the River Lee Navigation, including the Enfi ...
.
Etymology
The brook is named from the hamlet Turkey Street, which is recorded as ''Tokestreete'' (1441), ''Tuckhey strete'' (1610), ''Tuckey street'' (1615), and ''Turkey street'' (1805) (probably street of houses, i.e. hamlet, from
Middle English
Middle English (abbreviated to ME) is a form of the English language that was spoken after the Norman conquest of 1066, until the late 15th century. The English language underwent distinct variations and developments following the Old English p ...
''strete'', associated with a family called ''Toke'' or ''Tokey'').
The modern form of the name ''Turkey'', not in use before the 19th century, is no doubt due to
folk etymology
Folk etymology (also known as popular etymology, analogical reformation, reanalysis, morphological reanalysis or etymological reinterpretation) is a change in a word or phrase resulting from the replacement of an unfamiliar form by a more famili ...
.
Watercourse
The brook rises near the
Fir and Pond Woods nature reserve in Potters Bar, and at first flows in an easterly direction. Along its course it is joined by other streams including Hollyhill Brook,
Cuffley Brook
Cuffley Brook is a tributary of Turkey Brook. It runs through parts of Hertfordshire and the London Borough of Enfield, England. After the confluence of the two streams in Whitewebbs Park, the watercourse continues eastwards as Turkey Brook ...
, and the
Small River Lea
The Small River Lea is a minor tributary of the River Lea, which flows through the Lee Valley Park between Cheshunt and Enfield Lock. It forms part of the Turnford and Cheshunt Pits Site of Special Scientific Interest (SSSI) as it flows throu ...
. It flows alongside the M25 motorway and Crews Hill Golf Club, then goes past
Clay Hill,
Whitewebbs Park,
Forty Hill
Forty Hill is a largely residential suburb in the north of the London Borough of Enfield, England. To the north is Bulls Cross, to the south Enfield Town, to the west Clay Hill, and to the east Enfield Highway. Prior to 1965 it was in the his ...
and
Albany Park before merging with the
River Lee Navigation
The Lee Navigation is a canalised river incorporating the River Lea (also called the River Lee along the sections that are navigable). It flows from Hertford Castle Weir to the River Thames at Bow Creek (England), Bow Creek; its first lock is H ...
below
Enfield Lock
Enfield Lock is an area in the London Borough of Enfield, north London. It is approximately located east of the Hertford Road between Turkey Street and the Holmesdale Tunnel overpass, and extends to the River Lee Navigation, including the Enfi ...
.
Geology, origin and evolution
![Stream Under the Bridleway - geograph](https://upload.wikimedia.org/wikipedia/commons/8/88/Stream_Under_the_Bridleway_-_geograph.org.uk_-_1896928.jpg)
The main geological formation underlying the Turkey Brook catchment area is
Eocene
The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...
London Clay
The London Clay Formation is a marine geological formation of Ypresian (early Eocene Epoch, c. 56–49 million years ago) age which crops out in the southeast of England. The London Clay is well known for its fossil content. The fossils from t ...
. In some parts of the higher sections of the catchment area, the London Clay is overlain by "Pebble Gravel" and "Dollis Hill Gravel" (both
Quaternary
The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS). It follows the Neogene Period and spans from 2.58 million years ...
pre-glacial fluvial deposits), and by Quaternary glacial
till
image:Geschiebemergel.JPG, Closeup of glacial till. Note that the larger grains (pebbles and gravel) in the till are completely surrounded by the matrix of finer material (silt and sand), and this characteristic, known as ''matrix support'', is d ...
. Downstream of where Turkey Brook goes under the M25, there are
alluvium
Alluvium (from Latin ''alluvius'', from ''alluere'' 'to wash against') is loose clay, silt, sand, or gravel that has been deposited by running water in a stream bed, on a floodplain, in an alluvial fan or beach, or in similar settings. Alluv ...
and sand and gravel deposits on the Turkey Brook valley floor. And east of Forty Hill, the brook crosses extensive Quaternary river terrace deposits laid down by the
River Lea
The River Lea ( ) is in South East England. It originates in Bedfordshire, in the Chiltern Hills, and flows southeast through Hertfordshire, along the Essex border and into Greater London, to meet the River Thames at Bow Creek. It is one of t ...
.
[Se]
mapapps.bgs.ac.uk/geologyofbritain/
for more information on the distribution of all the formations mentioned here.[British Geological Survey (BGS) maps at a scale of 1:50,000 which cover the Turkey Brook catchment area can be viewed online a]
an
As a west bank tributary of the lower River Lea, Turkey Brook came into being about 400,000 years ago, after the
Anglian glaciation
The Anglian Stage is the name used in the British Isles for a middle Pleistocene glaciation. It precedes the Hoxnian Stage and follows the Cromerian Stage in the British Isles. The Anglian Stage is correlated to Marine Isotope Stage 12 (MIS 12), ...
. During that glaciation, ice from the north of England advanced at least as far south as
Watford
Watford () is a town and borough in Hertfordshire, England, 15 miles northwest of Central London, on the River Colne.
Initially a small market town, the Grand Junction Canal encouraged the construction of paper-making mills, print works, a ...
,
Finchley
Finchley () is a large district of north London, England, in the London Borough of Barnet. Finchley is on high ground, north of Charing Cross.
Nearby districts include: Golders Green, Muswell Hill, Friern Barnet, Whetstone, Mill Hill and H ...
and
Chingford
Chingford is a town in east London, England, within the London Borough of Waltham Forest. The town is approximately north-east of Charing Cross, with Waltham Abbey to the north, Woodford Green and Buckhurst Hill to the east, Walthamstow to the ...
.
Until the Anglian glaciation, the
River Thames
The River Thames ( ), known alternatively in parts as the The Isis, River Isis, is a river that flows through southern England including London. At , it is the longest river entirely in England and the Longest rivers of the United Kingdom, se ...
flowed north-eastwards via Watford, through what is now the
Vale of St Albans, then eastwards towards
Chelmsford
Chelmsford () is a city in the City of Chelmsford district in the county of Essex, England. It is the county town of Essex and one of three cities in the county, along with Southend-on-Sea and Colchester. It is located north-east of London a ...
and the
North Sea
The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the Norwegian S ...
. As a result of the glaciation, the Thames was diverted to a more southerly route, broadly along the line of its current course.
[Bridgland, DR and Gibbard, PL (1997), ''Quaternary River Diversions in the London Basin and the Eastern English Channel'', Géographie physique et Quaternaire, vol. 51, n° 3, 1997, pp. 337-346. Online a]
www.erudit.org/fr/revues/
See in particular Figure 1.
Prior to the Anglian glaciation, a "proto-Mole-Wey" river was flowing northwards from the
Weald
The Weald () is an area of South East England between the parallel chalk escarpments of the North and the South Downs. It crosses the counties of Hampshire, Surrey, Sussex and Kent. It has three separate parts: the sandstone "High Weald" in the ...
and
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 Areas of Outstanding Natural Beauty (AONBs): the Surrey Hills a ...
, through the "
Finchley depression" and
Palmers Green
Palmers Green is a suburban area and electoral ward in North London, England, within the London Borough of Enfield. It is located within the N13 postcode district, around north of Charing Cross. It is home to the largest population of Greek Cy ...
, to join the proto-Thames somewhere around
Hoddesdon
Hoddesdon () is a town in the Borough of Broxbourne, Hertfordshire, lying entirely within the London Metropolitan Area and Greater London Urban Area. The area is on the River Lea and the Lee Navigation along with the New River.
Hoddesdon is ...
, at what is today an altitude of around 60 metres. It was this river which, during the course of the early and middle
Pleistocene
The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...
, deposited the "Dollis Hill Gravel" at successive altitudes.
When the Anglian ice sheet diverted the Thames southwards, the Mole-Wey was cut off at
Richmond
Richmond most often refers to:
* Richmond, Virginia, the capital of Virginia, United States
* Richmond, London, a part of London
* Richmond, North Yorkshire, a town in England
* Richmond, British Columbia, a city in Canada
* Richmond, California, ...
. Meltwater from the retreating Anglian ice sheet gave birth to a south-flowing
lower River Lea, and that river cut into and followed in part the line of the former proto-Mole-Wey. It flowed into the newly diverted Thames, which at that time was spread over a wide flood plain extending as far north as
Islington
Islington () is a district in the north of Greater London, England, and part of the London Borough of Islington. It is a mainly residential district of Inner London, extending from Islington's High Street to Highbury Fields, encompassing the ar ...
.
And, as the ice sheet retreated, west bank tributaries of the lower Lea, such as Turkey Brook, flowed eastwards and south-eastwards from higher ground running roughly south-north through Potters Bar, down towards the newly formed lower River Lea. They, and their own tributaries, cut down successively through till left by the ice sheet, then through "Dollis Hill Gravel", and then into London Clay below.
It is not known at present whether Turkey Brook, and other west bank tributaries such as
Pymmes Brook
Pymmes Brook is located in North London and named after William Pymme, a local land owner. It is a minor tributary of the River Lea. The brook mostly flows through urban areas and is particularly prone to flooding in its lower reaches. To a ...
and
Salmons Brook
Salmons Brook is a minor tributary of the River Lea, located in the London Borough of Enfield.
Etymology
Salmons Brook is marked thus on Rocque's map of 1754, probably named from the family of John ''Salemon'' of Edmonton mentioned in 1274 ...
, followed valleys which had been in existence before the ice sheet covered the land, or whether they fashioned a substantially different landscape after the ice retreated. But it is known that today's tributaries of the upper Lea, such as the Rivers
Mimram
The River Mimram is a river in Hertfordshire, England.
Geography
The river valley known locally as the Mimram Valley is named after the River Mimram, which rises from a spring to the north-west of Whitwell, in North Hertfordshire, England, an ...
and
Stort
The River Stort is a river in Essex and Hertfordshire, England. It is 24 miles (38 km) long and flows from just south of the village of Langley to the River Lea at Hoddesdon.
The river's name is a back-formation; the town of Bishop's Stor ...
, follow broadly the same lines as pre-glaciation valleys, so, by analogy, it is quite possible that elements at least of the pre-glaciation topography of the lower Lea basin are reflected in today's relief.
![Footbridge Over Turkey Brook - geograph](https://upload.wikimedia.org/wikipedia/commons/1/1f/Footbridge_Over_Turkey_Brook_-_geograph.org.uk_-_1988249.jpg)
In the case of Turkey Brook immediately after the glaciation, that stream joined the River Lea somewhere around Forty Hill, where there is a deposit of "Boyn Hill Gravel".
That gravel, which is on the highest of the river terraces left by the post-Anglian lower River Lea, marks the line followed by the Lea after the retreat of the ice sheet.
During the course of the following 400,000 years, the lower Lea moved steadily eastwards, leaving river terrace deposits of decreasing age and altitude as it did so. Turkey Brook thus extended its course eastwards from Forty Hill, across the valley floor of the lower Lea, past Turkey Street, to where it today flows into the River Lee Navigation below Enfield Lock.
Stream pattern modification near Forty Hill
The drainage pattern in this area continues to evolve. In particular, Turkey Brook has, in the recent geological past, changed its course just after Hilly Fields. It formerly flowed south-eastwards, along what is today a "dry" channel along the south side of Forty Hill. Today, it turns northwards through Beggars Hollow to join Cuffley Brook in Whitewebbs Park. From there it continues eastwards, along the north side of Forty Hill.
At Boyn Hill time (about 400,000 years ago), Cuffley Brook and Turkey Brook joined the River Lea at points not far away from each other, north and south of where Forty Hall is today, at what is now an altitude of c50m.
Then the River Lea moved steadily towards the east. And, as a contour map shows, the two brooks each extended eastwards with the Lea, but stayed apart. The Lea and the two brooks cut down into the London Clay (to a today's altitude of c35m), thus defining the north, east and south sides of what was becoming Forty Hill.
The brooks approached each other quite closely either side of Beggars Hollow (close to where, today, the
Rose and Crown public house is located on Clay Hill). The dividing line between them was thus lowered by erosion at that point.
Later, the Lea moved further east to its present line, well away from Forty Hill, cutting down to a today's altitude of about 20 metres.
The low point between Turkey Brook and Cuffley Brook at Beggars Hollow was breached. Turkey Brook thus changed its course, there to go north-east, through what is defined as a
water gap
A water gap is a gap that flowing water has carved through a mountain range or mountain ridge and that still carries water today. Such gaps that no longer carry water currents are called wind gaps. Water gaps and wind gaps often offer a prac ...
. As a result, Turkey Brook joined Cuffley Brook in Whitewebbs Park and the merged stream continued eastwards along the former course of Cuffley Brook. But east of that junction, the stream is now known as Turkey Brook.
A dry, former stream channel at c30m was left, running just north of Clay Hill, from Beggars Hollow to a point close to today's junction of Clay Hill and Baker Street. That channel now defines the southern boundary of Forty Hill.
When the
New River was built, it followed the 30m contour from
Hertfordshire
Hertfordshire ( or ; often abbreviated Herts) is one of the home counties in southern England. It borders Bedfordshire and Cambridgeshire to the north, Essex to the east, Greater London to the south, and Buckinghamshire to the west. For govern ...
south towards
London
London is the capital and largest city of England and the United Kingdom, with a population of just under 9 million. It stands on the River Thames in south-east England at the head of a estuary down to the North Sea, and has been a majo ...
, down the Lea valley. But, in Enfield, the engineers who constructed it took the New River on a loop going west, to the north of Forty Hill, and then across Cuffley Brook near Flash Lane (and, later, across an aqueduct there). From that point, they took it south-east, through the water gap at Beggars Hollow, along the dry channel north of Clay Hill, and down to where Ladysmith Road is today. Then the New River continued on its southward course, towards Enfield Town.
The New River was later straightened to flow southwards continuously, to the east of Forty Hill. An aqueduct was built for the New River to cross Turkey Brook near Maidens Bridge. This left the former course of the New River as it is today, curling through Whitewebbs Park, passing through Beggars Hollow and following the dry channel.
Rose and Crown Public House, Clay Hill, Enfield - geograph.org.uk - 371058.jpg, Rose and Crown Public House, Beggars Hollow, Clay Hill, Enfield (geograph.org.uk).
Flash-Lane-aqueduct--info-board--2.jpg, The route (in blue) of the former "Whitewebbs loop" of the New River (from an information board at the Flash Lane aqueduct).
Maiden's Bridge over Turkey Brook - geograph.org.uk - 3020954.jpg, Maiden's Bridge over Turkey Brook, at the north-east foot of Forty Hill (geograph.org.uk).
Ecology
The brook is mostly shallow, fast flowing and clean and can support wildlife.
Coarse fish including
dace
A dace is a small fish that can be one of many different species. The unmodified name is usually a reference to the common dace (''Leuciscus leuciscus''). This, like most fish called "daces", belongs to the family Cyprinidae, mostly in subfamily ...
use the brook to
spawn
Spawn or spawning may refer to:
* Spawn (biology), the eggs and sperm of aquatic animals
Arts, entertainment, and media
* Spawn (character), a fictional character in the comic series of the same name and in the associated franchise
** '' Spawn: ...
.
Flood risk
It is estimated that, along the course of Turkey Brook, there are "an estimated 92 properties in Oakmere (Potters Bar), and 3 near Enfield Wash at risk of fluvial flooding during a 1% annual probability event".
[Environment Agency, 2013]
''Managing flood risk in the lower Lea catchment, today and in the future''
page 29.
Notes and References
External links
*
{{authority control
Rivers of Hertfordshire
Geography of the London Borough of Enfield
Tributaries of the River Lea
Rivers of London
1Turkey
Crews Hill