The Catherine shaft, named after one of Sir William Thomas’s three daughters was sunk in 1909 by the Lewis Merthyr Consolidated Collieries Ltd. Sir William Thomas Lewis, Baron of Senghenydd was the Head of this colliery Combine which had extensive colliery properties and interests throughout South Wales.
The Catherine shaft was sunk to a depth of 272 yards and became the Upcast shaft: it proved the No. 2 Rhondda seam at a depth of 250 yards.
The No. 2 Rhondda coal seam is here split into two or three leaves with some four feet of workable coal in total. The intervening dirt bands required major coal washery facilities and plant at the surface to separate the clean coal from the dirt.
It was worked from the Catherine and Anne shafts by long wall stall and long wall conveyor systems; the general dip of the coal measures here is 7 inches per yard to the south. To the north of the shafts, the geology of the strata proved difficult with much faulting and folding. Developments to the south of the shafts encountered high water inflows which resulted in high pumping costs.
It is said that the colliery was very well equipped with up to date machinery both on the surface and underground. It had its own electrical generating plant which provided electrical power to surface and underground plant and machinery.