By the 1830s coal mining was beginning to have a significant impact on rural villages such as Treoes.
Coal mining had begun in nearby, Bryncethin, Kenfig and Rhondda, and there were other industries as well, including a woollen mill in Llanblethian, a pottery at Ewenny and a tannery at Boverton.
In 1831 the railway arrived in Bridgend and this brought further trade and commercialisation.
These events led to a shortage of farmworkers and for the larger estates this was becoming a major problem which inevitably led to higher wages paid for agricultural work in the Vale. This was not enough to compete with new industries however and as a result, there was an influx of seasonal workers from Cardigan, Somerset and Ireland. Many of these migrant workers settled in the Vale and some in Treoes and Llangan.
In 1815 an important lead mine was opened at Tewgoed in Llangan- where ore was also smelted. Walter Davies wrote of this mine:
“Here the grand vein runs east and west through the limestone and lading (inclining) itself to the noon sun. On the south side of the vein is a calcareous earth called liman. The vein itself called the red vein, from the colour of its contents, has nodules of lead imbedded into it, with a rider of calcareous freestone (fine grained limestone that can be easily sawed). Three parallel veins called blue veins, run obliquely from the North West into this red vein. The ore of the blue veins is Galens, or the laminar Potters Ore. Near the junction of the blue veins with the transverse red vein, a shaft was sunk, and a rich belly of steel grained ore was discovered. This induced the miners to sink two other shafts near the junction of the other two blue veins with the red vein, with equal success” (Stewart Williams, Glamorgan Historian)
At Gelliarual the ruins of the engine house and the boiler house stack can still be seen – Miners came from Cornwall to work in the mine. It is said that the Fox and Hounds did a roaring trade.