Extensive mining activities in the Hendre Valley, with shafts and mounds remaining to the south of the valley and the A541 Road. The largest of these shafts are found in the Garreg-Boeth Woods and Big Wood, located at SJ18656760. These workings extend eastwards to SJ19156755.

The Garreg-Boeth Vein was later developed by the South Halkyn and Rhydymwyn Mining Company after the Halkyn Deep Level Tunnel reached the sett in 1908, marking a significant development in the area’s mining history.

The Tyddyn-y-barcud Vein ran east to west to the north-west of Big Wood. Smith (1921) mentions seven shafts along the Tyddyn-y-barcud Vein: Robert’s, Pritchard’s, Eyton’s, Williamson’s, Marquis, Tyddyn-y-barcud, and Ddol.