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 to join the River Lea near Enfield Lock.
Cuffley Brook is one of the longest tributaries of the River Lea, snaking for several miles through the south-east Hertfordshire hills. [1] It rises in Northaw Great Wood, north west of Cuffley, and is joined there by Grimes Brook. Northaw Brook and Hempshill Brook join Cuffley Brook south of Cuffley, close to Soper's Viaduct (on the Hertford Loop railway line). The stream then goes under the M25 motorway, passes close to Crews Hill, and enters Whitewebbs Wood. There, it goes under the Flash Lane Aqueduct [2] (on a former course of the New River), before reaching a confluence with Turkey Brook, in the London Borough of Enfield, at the north-west foot of Forty Hill.
The oldest geological formation to outcrop within the Cuffley Brook catchment area is Cretaceous Chalk. [3] [4] This reaches the surface in the floor of the Hempshill Brook valley. The chalk also comes close to the surface in Northaw Great Wood, where swallow holes in overlying sediments near Cuffley Brook indicate that the chalk is not far below. [5] [6]
Overlying the chalk are fairly extensive areas of formations of the Lambeth Group, [7] notably of the Reading Formation, [8] which consists mostly of silty clay and sand. But samples of the distinctive "Hertforshire Puddingstone" have also been found in Northaw Great Wood. [9]
Overlying the above formations is Eocene London Clay, which is the main geological formation in the Cuffley Brook catchment area.
An early Pleistocene fluvial deposit known generally as "Pebble Gravel" covers an extensive area on higher parts of the catchment area - for example, around Northaw and Newgate Street. [10] [11]
A little lower than the Pebble Gravel, but still mostly on interfluves (for example, near Crews Hill), is another pre-glacial formation of fluvial origin known as "Dollis Hill Gravel". [12]
Overlying some of the Pebble Gravel and Dollis Hill Gravel are notable deposits of glacial till, especially in the eastern and northern upper parts of the catchment area (for example around Goffs Oak and Epping Green).
Finally, throughout almost the whole length of Cuffley Brook and its tributaries, deposits of recent alluvium and valley sand and gravel are found along the valley floors.
As a west bank tributary of the lower River Lea, Cuffley Brook came into being about 400,000 years ago, after the Anglian glaciation. During that glaciation, ice from the north of England advanced at least as far south as Watford, Finchley and Chingford.
Until the Anglian glaciation, the River Thames flowed north-eastwards to Hertford via Watford, through what is now the Vale of St Albans, then eastwards towards Chelmsford and the North Sea. As a result of the glaciation, the Thames was diverted to a more southerly route, broadly along the line of its current course. [13]
Prior to the Anglian glaciation, a "proto-Mole-Wey" river was flowing northwards from the Weald and North Downs, through the "Finchley depression" and Palmers Green, to join the proto-Thames somewhere around Hoddesdon, at what is today an altitude of around 60 metres. [14] It was this river which, during the course of the early and middle Pleistocene, deposited the "Dollis Hill Gravel" at successive altitudes. [15]
When the Anglian ice sheet diverted the Thames southwards, the Mole-Wey was cut off at Richmond. [16] 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. [17]
And, as the ice sheet retreated, west bank tributaries of the lower Lea, such as Cuffley 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 Pebble Gravel, "Dollis Hill Gravel", London Clay, and, in the case of Cuffley Brook, beds in the Lambeth Group beneath that.
It is not known at present whether Cuffley Brook, and other west bank tributaries of the Lea such as Pymmes Brook, Salmons Brook and Turkey Brook, 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 and Stort, 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. [18]
In the case of Cuffley Brook immediately after the glaciation, that stream joined the River Lea somewhere around Forty Hill, where there is a deposit of "Boyn Hill Gravel". [19] 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.
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 Hill is today, at what is now an altitude of c50 metres.
Then the River Lea moved steadily towards the east, leaving river terrace deposits of decreasing age and altitude as it did so. And, as a contour map shows, the two brooks each extended eastwards with the Lea, but stayed apart.
However, 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.
Eventually, in the recent geological past, the low point between Turkey Brook and Cuffley Brook at Beggars Hollow was breached. [20] Turkey Brook thus changed its course, there to go north-east, through what is defined as a water gap. 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 (and, locally, as Maidens Brook).
When the New River was built, it followed the 30m contour from Hertfordshire south towards London, 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 [2] ). From that point, they took it south-east, through the water gap at Beggars Hollow, along the former course of Turkey Brook, and down 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, and passing through Beggars Hollow.
The upper parts of the Cuffley Brook valley (and the valleys of its headwaters) seem disproportionately deep for such small streams. For example, from the top of Plough Hill, Cuffley, the ground falls about 50 metres in altitude to the valley bottom in barely more than half a kilometre. But we are currently in an interglacial period, and the streams would have been flowing more strongly than today at times of "high discharge, under cold climatic conditions". [21] And, at such times, soil cover and vegetation would have been much thinner than today, thus facilitating greater erosion. Furthermore, as the River Lea itself cut down as it moved eastwards, it lowered the base level of its tributary streams, like Cuffley and Turkey Brooks. That would have enabled the streams to become further incised into the higher ground to the west of the Lea flood plain.
The geology of Hertfordshire describes the rocks of the English county of Hertfordshire which are a northern part of the great shallow syncline known as the London Basin. The beds dip in a south-easterly direction towards the syncline's lowest point roughly under the River Thames. The most important formations are the Cretaceous chalks, which are exposed as the high ground in the north and west of the county, and the Cenozoic rocks made up of the Paleocene age Reading beds and Eocene age London Clay that occupies the remaining southern part.
The River Brent is a river in west and northwest London, England, and a tributary of the River Thames. 17.9 miles (28.8 km) in length, it rises in the Borough of Barnet and flows in a generally south-west direction before joining the Tideway stretch of the Thames at Brentford.
The Goring Gap is a topographical feature on the course of the River Thames. The Gap is located in southern England where the river, flowing from north to south, cuts through and crosses a line of chalk hills in a relatively narrow gap between the Chiltern Hills and the Berkshire Downs. The Gap is approximately 10 miles (16 km) upstream of Reading and 27 miles (43 km) downstream of Oxford. The Gap is named after the town of Goring-on-Thames in Oxfordshire. That town is on the east bank of the river at Goring Gap, and Streatley is immediately opposite, on the west bank.
The Bytham River is said to have been one of the great Pleistocene rivers of central and eastern England until it was destroyed by the advancing ice sheets of the Anglian Glaciation around 450,000 years ago. The river is named after Castle Bytham in Lincolnshire, where the watercourse is said to have crossed the Lincolnshire limestone hills in a valley now buried by Anglian till. West of that location, its catchment area included much of Warwickshire, Leicestershire and Derbyshire. East of that location, the Bytham flowed across what is now the Fen Basin to Shouldham, then southward to Mildenhall, then eastward across East Anglia. It met the Proto-Thames in a delta near what is now the Norfolk/Suffolk border and flowed into the North Sea. Britain was then joined to the Continent by a land bridge and the Bytham joined the North Sea somewhere beyond the northern end of that land bridge.
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. It correlates to Marine Isotope Stage 12, which started about 478,000 years ago and ended about 424,000 years ago.
The Hoxnian Stage was a middle Pleistocene stage of the geological history of the British Isles. It was an interglacial which preceded the Wolstonian Stage and followed the Anglian Stage. It is equivalent to Marine Isotope Stage 11. Marine Isotope Stage 11 started 424,000 years ago and ended 374,000 years ago. The Hoxnian is divided into sub-stages Ho I to Ho IV. It is likely equivalent to the Holstein Interglacial in Central Europe.
London is the largest urban area and the capital city of the United Kingdom. It lies in the southeastern part of the island of Great Britain. The London region covers 1,579 square kilometres (610 sq mi), and had a population of 8.982 million in 2019 and a population density of 5,596 people per square km in 2021. A larger area—the London Metropolitan Region or the London Metropolitan Agglomeration—covers 8,382 square kilometres (3,236 sq mi) and had 12,653,500 people, at a density of 1,510 per square kilometre.
Dollis Brook is a waterway which runs through Barnet in north London. It is a tributary of the River Brent, which is itself a tributary of the River Thames.
Horsenden Hill is a hill and open space, located between the Perivale, Sudbury, and Greenford areas of West London. It is in the London Borough of Ealing, close to the boundary with the London Borough of Brent. It is one of the higher eminences in the local area, rising to 85 m (276 ft) above sea level, and the summit forms part of the site of an ancient hillfort. It is the site of a trig point, TP4024.
The Ancestral Thames is the geologically ancient precursor to the present day River Thames. The river has its origins in the emergence of Britain from a Cretaceous sea over 60 million years ago. Parts of the river's course were profoundly modified by the Anglian glaciation some 450,000 years ago. The extensive terrace deposits laid down by the Ancestral Thames over the past two million years or so have provided a rich source of material for studies in geology, geomorphology, palaeontology and archaeology.
The Lea Valley, the valley of the River Lea, has been used as a transport corridor, a source of sand and gravel, an industrial area, a water supply for London, and a recreational area. The London 2012 Summer Olympics were based in Stratford, in the Lower Lea Valley. It is important for London's water supply, as the source of the water transported by the New River aqueduct, but also as the location for the Lee Valley Reservoir Chain, stretching from Enfield through Tottenham and Walthamstow.
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 historic county of Middlesex.
Turkey Brook is a river in the northern outskirts of London. It rises in Potters Bar, Hertfordshire, and flows broadly eastwards to merge with the River Lea Navigation near Enfield Lock.
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 alleviate the problem the brook has been culverted in many areas. Part of it is a Site of Borough Importance for Nature Conservation, Grade II.
Salmons Brook is a minor tributary of the River Lea, located in the London Borough of Enfield.
The Norwich Crag Formation is a stratigraphic unit of the British Pleistocene Epoch. It is the second youngest unit of the Crag Group, a sequence of four geological formations spanning the Pliocene to Lower Pleistocene transition in East Anglia. It was deposited between approximately 2.4 and 1.8 million years ago, during the Gelasian Stage.
Moor Mill Quarry, West is a 0.16-hectare (0.40-acre) geological Site of Special Scientific Interest in How Wood in Hertfordshire. The local planning authority is St Albans City and District Council. It was notified in 1992 as representing the former Moor Mill Quarry SSSI, which was lost to landfill operations. It is listed by the Geological Conservation Review.
The Finchley Gap is a location centred on Church End, Finchley, in north London, England. As a topographical feature approximately eight kilometres wide, lying between higher ground to the north-west and to the south-east, it has probably existed for the last one million years or more.
This article describes the geology of the Broads, an area of East Anglia in eastern England characterised by rivers, marshes and shallow lakes ('broads'). The Broads is designated as a protected landscape with 'status equivalent to a national park'.
Waldringfield Pit is a 0.8-hectare (2.0-acre) geological Site of Special Scientific Interest between Martlesham Heath and Waldringfield in Suffolk. It is a Geological Conservation Review site.