The Disappearing River Mole
Swallows in the banks of the River Mole, near Burford Bridge.
The River Mole between Dorking and Leatherhead flows both on the surface and in a system of underground passages in the Chalk bedrock. The water enters the underground system via a number of swallow holes – not normally seen when the river level is high. At times of drought the river bed can be exposed and the swallow holes become visible. The subterranean flow can periodically be seen emerging at Fetcham Mill Pond. These features have long been recognised and were first illustrated in Brayley’s Topographical History of Surrey in 1850, from which this illustration is taken.
Map of Mole Valley between Mickleham and Leatherhead.
The river bed of the Mole between the Mickleham Bridge and the Thorncroft Bridge has been exposed in parts during the dry spell of July 2022. MVGS member Tod Wilson has photographed the situation at various points along the river – shown as the following seven photographs. Also shown is the Ham Bank locality where the river bed and swallow holes were exposed in the drought of 1949. [Image © GoogleEarth].
River Mole at the Stepping Stones near Burford Bridge in July 2022.
Reduced surface flow of the River Mole at the Stepping Stones, downstream to left (NGR TQ 1723 5130).
Exposed river bed at Norbury Park in July 2022.
View looking north, Young Street road bridge in distance (TQ 1639 5513).
Mole river bed at Young Street, Leatherhead in July 2022.
Low water level in River Mole at Young Street Bridge (A246 road) looking north, downstream (NGR TQ 1637 5517).
Ham Bank near Mickleham in 1949
The drought in 1949 exposed the Mole river bed at Ham Bank, near Mickleham (c. TQ 161 527) and the event was recorded in several photographs taken by J. Rhodes - this and following two images. View of exposed swallow hole looking north. [Image © British Geological Survey, Geoscenic Collection, no. P208320].
Ham Bank near Mickleham in 1949
View of exposed swallow hole looking south. [Image © British Geological Survey, Geoscenic Collection no. P208321].
Geological Sites in the Mole Valley and a tour of Denbies Vineyard
Denbies Wine Estate
Map showing legacy sites of extractive industries around Dorking.
A variety of sedimentary rock types has been extracted from quarries in the area around Dorking from as early as the 17th century. The Lower Chalk has been quarried at Dorking, Brockham and Betchworth for the manufacture of lime - remnants of the kilns can still be seen at the two latter sites. Firestone (for building) and hearthstone (used as an abrasive agent) from the Upper Greensand were originally mined at Brockham and Betchworth. In the twentieth century the Lower Greensand has been worked for building sand in several pits around Buckland and an extensive quarry in North Holmwood extracted the Weald Clay for brickmaking. [Image © GoogleEarth].
Dorking Limeworks in 1929.
The Lower Chalk has been quarried at Dorking for making lime since at least the seventeenth century. The quarry at Ranmore Road is shown here, looking northwest, in 1929. It was operated by the Dorking Greystone Lime Works Company and their ‘Dorking Lime’ was used in the construction of the Houses of Parliament and other London buildings. The old quarry is today the site of the MVDC recycling depot. [Photograph: J Rhodes, 1929. Image © British Geological Survey, Geoscenic Collection, no. P204581].
Brockham Limeworks Quarry Scar.
The Lower Chalk was quarried on a large scale at Brockham from the mid nineteenth century. Originally operated by the Brockham Brick Company, the quarry became part of the Dorking Greystone Lime Company before operations ceased in 1936. The site is now owned by Surrey County Council and managed by the Surrey Wildlife Trust. [Photograph: MVGS member].
Detail of old quarry face at Brockham.
Normal, sub-listric, fault in the Lower Chalk - the throw is down to the right (east) of approximately 3 meters. [Photograph: MVGS member].
Lime Kilns at Brockham Limeworks in 1929.
Lime at Brockham was manufactured in the patented ‘Brockham Kiln’ designed by the company’s secretary and manager Alfred Bishop in 1899. These were able to produce lime on a continuous basis rather than separately charging each batch of production. [Artist and source of illustration unknown].
Old kiln battery at Brockham in 2006.
The kiln battery shown here is now a Grade II scheduled ancient monument owned by Surrey county Council and managed by the Surrey Wildlife Trust; the structure provides a habitat for bat hibernation. The site is today largely overgrown and restoration of the kilns has yet to take place. [Photograph: MVGS member].
Old Shaft near Brockham kilns.
Firestone and hearthstone were first mined at Brockham in the 1870s by a complex of underground drift mines that followed the Upper Greensand beds below the Chalk. This abandoned vertical shaft was probably added later – perhaps to improve ventilation. The mines closed in 1898, but were re-opened in 1904 and finally closed in 1925. [Photograph: MVGS member].
Panorama of Betchworth Quarry and Limeworks in 1929.
The Chalk quarry at Betchworth was operated by the Dorking Greystone Lime Company from 1865 to 1959. This photograph, looking southwest, was taken by J. Rhodes in 1929. [Image © British Geological Survey, Geoscenic Collection, no. P204595].
Betchworth Quarry in 1963.
The excavation shown here is in the dull greyish somewhat marly Lower Chalk. Earlier workings exploited the higher section of mainly white Middle Chalk seen in the upper quarry scar. The quarried chalk can be seen loaded into the adjacent kilns. [Photograph: J M Pulsford, 1963. Image © British Geological Survey, Geoscenic Collection, no. P209836].
Betchworth Quarry in 2008.
A similar view to the preceding photograph. The quarry workings at Betchworth have been reclaimed by landfill and returned to agricultural use. The top of the old quarry face in the Middle Chalk is still visible. [Photograph © Ian Capper; https://www.geograph.org.uk/photo/869919].
Kiln Tower at Betchworth Quarry.
The kiln tower at the Betchworth Limeworks dates from c.1901. Known as a ‘Smidth Kiln’, it comprises two chimneys encased in a single tower, but serving only one firing chamber - the prominent archway was the firing floor. It appears that this kiln did not see any significant use. The structure is a Grade II listed building. [Photograph: MVGS member].
Weald Clay exposures in North Holmwood Brickpit.
The North Holmwood quarry was in operation from 1914 to 1981, producing up to 15 million bricks a year from the Weald Clay. This view of the quarry face shows interbedded brown and blue clays. The brown clay was originally used for hand-made bricks and a mixture of the two was used for machine-made bricks. [Photograph: J M Pulsford, 1961. Image © British Geological Survey, Geoscenic Collection, no. P209619].
Faults in the Weald Clay at North Holmwood.
Reverse fault in the Weald Clay at North Holmwood quarry. Note the overthrust in the prominent light-coloured horizon and the disturbance in the overburden which displays an antithetic accommodation fault. [Photograph: J Rhodes, 1949. Image © British Geological Survey, Geoscenic Collection, no. P208325].
Lower Greensand at Vincents Lane, Dorking.
Old quarry exposure of the Lower Greensand Folkestone Beds overlain by raised terrace drift deposits of loam and gravel related to a tributary of the River Mole. The quarry is now the site of a trading estate. [Photograph: J Rhodes, 1929. Image © British Geological Survey, Geoscenic Collection, no. P204565].
Buckland (Park) Quarry restored for leisure use.
The Buckland (Park) Quarry extracted building sand from the Lower Greensand Folkestone Beds between 1960 and 1989. Since the 1990s the quarry has been restored and landscaped and is now managed by the Buckland Estate as a leisure facility. Part of the old processing works, seen on the left, has been converted into a boathouse. [Photograph © Buckland Estate].
Field Excursion to the Lizard Peninsula: A Journey to the Centre of the Earth
The objective of the trip was to examine exhumed mantle and oceanic crust and the overlying deepwater facies of Devonian age (c.400 Ma) exposed around the Lizard Peninsula.
Overlying deepwater facies: Pendower Formation mudstones overlain by Pleistocene raised beach, Pendower Beach.
Mantle to crust transition at Coverack Cove. Mantle peridotites (left foreground), and crustal gabbros (far right distance). Troctolites (centre, and under the bay) mark the position of the Mohorovicic Discontinuity.
Detail of gabbro: dark grey plagioclase (altered to white prehnite), green augite, green olivine, black ilmenite.
Hornblende schists (amphibolites) at Cadgwith Cove. A shear zone runs through the centre of the outcrop.
An Excursion to the Dorking Caves
Field Excursion to Philpott's Quarry, West Hoathly, Sussex
Briefing for the group at the start of the trip. The quarry has exposures of the Lower Cretaceous Tunbridge Wells Sandstone below an overburden of Grinstead Clay.
Sedimentary features in the Tunbridge Wells Sandstone: cross-bedding, younging to the left, with iron liesegang.
Some Other Member Activities
Visit to Ibstock Quarry and Brickworks, Beare Green. The bricks are made from the Lower Cretaceous Weald Clay.