Description

The monument comprises a unique surviving example of a colliery ventilation furnace with hillside flue. This type of structure was common in the non-ferrous metal smelting industries, and was also used to ventilate mines. A fire burning in the mine drew air through the underground workings and expelled it up the flue. The flue was of large diameter to accommodate a large body of air. The furnace at Cwm Pelenna was connected with the Fforch-dwm level, driven by Robert Parsons and Charles Strange in the late 1830s. The colliery was re-worked from the 1890s as the Mercantile No 1, then the Blaenmawr Navigation Colliery, the Garth Level, and finally by the National Coal Board as Garth Tonmawr Colliery until closure in 1964.

The head of the flue is a short stone stack, built on a rectangular plan with rounded corners. The flue is also stone built, with an arched roof and flat floor. It runs downhill to the ruins of a probable post-war fan house which seems to have re-used it in part. The lower part of the flue is underground but is discernable as a slight ridge at the surface.

The monument is of national importance for its potential to enhance our knowledge of the early nineteenth century coal mining industry. The structures may be expected to contain archaeological information in regard to chronology, building techniques and functional detail. A ventilation furnace may be part of a larger cluster of industrial monuments and their importance can further enhanced by their group value.

The scheduled area comprises the remains described and areas around them which related evidence may be expected to survive.

Source: Cadw