Geology Site Account

Site name: Langtons former gravel pit, Weald Country Park, South Weald, (adjoining Sandpit Lane at the eastern edge of the park)

Grid reference: TQ 5779 9476

Brief description of site:

Langtons is a disused gravel pit that is now a small fishing lake surrounded by woodland. It is an important geological site because it was one of the very few places where the 'Bagshot Pebble Bed' was formerly exposed.

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Summary of the geological interest:

The Bagshot Pebble Bed is a layer of well-rounded flint pebbles that occurs on top of the Bagshot Sand. It has been interpreted by some geologists as being formed on the floor of a shallow, subtropical sea some 50 million years ago immediately after deposition of the Bagshot Sand; perhaps representing a beach as the coastline migrated across Essex. Others consider it to be younger, perhaps a marine deposit laid down at the very beginning of the Ice Age.

On top of the pebble bed is a layer of sandy gravel that is distinctly different to the pebble bed, but similar to gravel found at other high points, such as High Beach, Langdon Hills and Rayleigh. This high level gravel is thought to have been laid down during the early Ice Age, perhaps one million years ago, by northward-flowing tributaries of the River Thames (which at that time flowed across north Essex and Suffolk). Formerly called Pebble Gravel and shown on modern geological maps as 'Stanmore Gravel', it consists mostly of flint but also other rock types proving that Kent was the source of these rivers.

The pit is overgrown and neither the pebble bed nor the gravel is currently visible.

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Scientific interest and site importance

The pit at Langtons once provided a fine section of Bagshot Pebble Bed overlain by Pebble Gravel (now called Stanmore Gravel).

Whitaker (1889) states that the thickness of the Bagshot Pebble Bed is 'about 15 feet' and provides an illustration that shows much fine soft sand in the upper part of the bed with the pebbles closely packed in the lower part. In his illustration the pebble bed is overlain by up to 6 feet of pebbly gravel (Pebble Gravel).

The Langtons section was also illustrated in Dines and Edmunds (1925) who described the 'Bagshot Pebble Bed' as 'round, blue flint pebbles, some partly desilicified, from half an inch to two inches in diameter, in a coarse white, sandy matrix; a seam of light-grey silty clay halfway down and several minor intercalations of sand'. Trial borings made at that time show that below the floor of the pit the Bagshot Pebble Bed 'passes down into coarse white sand composed partly of flint fragments'.

Dines and Edmunds describe the 'Pebble Gravel' at the top of the pit as a 'three foot bed of elongated flint pebbles with their longer axes vertical and average lengths of three inches. Some worn nodular flints and a few pebbles of Bunter quartzite and of sarsen, in a matrix of red and grey clay'.

The site is not only of historical interest but has potential for research. One issue that needs to be resolved is whether some of the old accounts are describing this pit or a pit on the east side of Sandpit Lane referred to in Middlemiss (1955).

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Other information

The geology of the park and South Weald village is varied and interesting. It is also very typical of this part of Essex making this site important for the teaching of geology. Langtons Pit is of particular educational interest as an example of one of the many controversial geological debates on the origin of rocks that has still not been resolved.

The pit is currently separated from the Country Park by a fence and permission to visit should be obtained from the Ranger Service. Cars should be parked in the main public car park. From here it is about 10 minutes walk across the park to the pit. Brentwood railway station is within 2 miles (about 3 kilometres).

Weald Country Park is noticeably hilly. As a result there are many fine views. The park is managed by Essex County Council with Brentwood Borough Council.