Dinas Silica Mine

Cadw's description

Summary description and reason for designation

The following provides a general description of the Scheduled Ancient Monument.

Silica rock was first discovered and extracted at Dinas in the 1780s, with a tramway linking the site to the Neath Canal opened in 1807. Large scale mining started in the early 1820s when local businessman, William Weston Young leased the land at Craig y Dinas from the marquess of Bute and founded the Dinas Firebrick Company. In 1821 Weston Young had invented a heat-resistant brick made using the high-quality silica rock found at Dinas, that could be used to line the inside blast furnaces. The bricks, known as Dinas Bricks, were a key component in the development of the iron, copper and steel smelting industry, and were exported around the world from the brickworks built by the Dinas Firebrick Company at Pont Walby. The earliest workings comprised surface quarries cut into the upper levels of the silica rock, with the quarried materials transported from the site along a tramroad that ran across the top of the adjacent Craig y Ddinas Hillfot (BR178). In the later 19th or early 20th century underground mining of the upper levels of the silica deposits started, with pillar and stall workings cut through the inclined deposits. A spur of tramroad connected the upper mine entrance with the earlier tramroad. The quarries, several entrances to the upper mine workings, the embanked tramroad and the remains of a powder store survive in the upper part of the scheduled area.

By 1914 mining had started in the lower levels of the silica deposits, with entrances cut adjacent to the Afon Sychryd and a new tramroad built that took materials across the river, through a tunnel to Bwa Maen and west along the Sychryd. In 1930 a new tramroad was built along the north bank of the river which included a perilous section of ledge cut into the face of the rock from which material was tipped into a series of hoppers several metres below. This system was replaced at some stage by a steep incline made by concreting steel girders to the rock to hold a suspended tramroad over the rock adjacent to the waterfall. By the mid-20th century the tramroad had been replaced by an aerial ropeway that carried tubs of silica rock from the mine 550m down the valley to a hopper located adjacent to the tramroad in what is now the Dinas Rock car park. The aerial ropeway used heavy duty cables suspended by a series of pylons and was driven by a compressor located at the mine entrance. Several buildings were constructed outside the mine adjacent to the Afon Sychryd, these included offices, stores, a canteen, a locomotive shed and others housing the machinery that drove the mine. The mine finally closed in 1964 and all the buildings were removed from the surface and their remains dumped into the mine workings. Traces of the different phases of workings can be seen within the lower part of the scheduled area, including concrete pads for buildings, the remains of sections of tramroad, concrete pads that held a pylon, steel girders from the suspended section of tramroad and a number of tubs used on the aerial ropeway that were placed in the river to protect a section of tramroad from flooding.

The monument is of national importance for its potential to enhance our knowledge of 19th and 20th century mining practices. It retains significant archaeological potential, with a strong probability of the presence of associated archaeological features and deposits.

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