Shaft mounds and earthworks south of Bentley Grange Farm are the remains of a medieval iron mining site between Emley and West Bretton in West Yorkshire. The medieval monastic grangeMonastic granges were outlying landholdings held by monasteries independent of the manorial system. They could be of six known types: agrarian, bercaries (sheep farms), vaccaries (cattle farms), horse studs, fisheries or industrial complexes. was started by the Cistercians of Byland Abbey in North Yorkshire. According to Historic England, the remains are among Britain’s best preserved mining landscapes pre-dating the Industrial Revolution. The remains are scheduled under the Ancient Monuments and Archaeological Areas Act 1979. The site has about 60 shafts dug to the shallow Tankersley ironstone bed.
Bentley Grange was established by the Cistercians of Byland Abbey in Yorkshire. The monastic grange had an iron forge by the late 11th century; iron smelting was possibly taking place by 1226. A mill dam on Bank Wood Beck may have powered bellows for a forge or furnace in the late-13th century. Iron working lasted until the mid-15th century when the grange was leased as agricultural land. When Byland Abbey was dissolved in 1538, Bentley Grange was recorded as enclosed pastures.
Mining resumed in the late 16th century when the Tankersley ironstone bed The Tankersley ironstone bed was named from its outcrop at Tankersley near Barnsley in South Yorkshire. was worked by the Wentworths of Bretton HallA country house on the north slope of the valley of the River Dearne in West Bretton near Wakefield, West Yorkshire, England. . Matthew Wentworth bought “all the myne, and delff of ironstone” around Bentley Grange. After the ironstone was exhausted the smithies continued to operate fuelled by charcoal. The furnace supplied pig iron to Colnebridge, Wortley Top Forge and Kirkstall in 1728.
In the 1950s much of the area surrounding the earthworks was opencasted for coal before being reinstated for agriculture. The area of scheduling is divided by Woodhouse Lane and the drive to Bentley Grange Farm. The largest area south of Woodhouse Lane, is defined by field boundaries.
Aerial photographs of the earthworks of the mining remains were taken in 1953 by J. K. St Joseph who made a connection with the documentary references to medieval iron working. He concluded that the shaft mounds were medieval iron-ore bell pits. Moorhouse and Wilmot’s 1985 survey concluded that many shaft mounds had clear platform working areas associated with the individual shafts, and suggested that they were probably made when mining by the Wentworths resumed in the 16th century rather than supplying the 13th-century monastic iron forges. The mounds overlay ridge and furrow, evidence of medieval arable farming. The ridge and furrow overlies earlier building platforms and small terraced enclosures that are interpreted as being medieval, possibly the remains of the monastic grange.
The ancient monument comprises the about 60 shaft mounds and associated earthworks. They form a rough grid pattern, the shafts about 50 metres (164 ft) apart. The smallest are about 25 metres (82 ft) in diameter, comprising rings of spoil around a central depression where the shaft was located. Most are around 40 metres (131 ft) in diameter, their earthworks are up to 3 metres (9.8 ft) high with flattened tops and central shafts, Others have off-set shafts and some have access ramps. Five shaft mounds in the western part of the monument are large and more complex with earthworks suggesting horse gins at the side of the shaft. The shaft mounds pre-date the Industrial Revolution, probably from the 16th century.