Modern quarrying started in Nant Gwrtheyrn shortly after 1850 to supply granite setts for paving and construction work in large cities. Three quarries were opened - Cae'r Nant (NPRN 40562), Porth y Nant and Carreg y Llam (NPRN 40533). Ships were loaded regularly from purpose built jetties, carrying setts to Liverpool, Manchester and Birkenhead. In 1878, the settlement of Porth y Nant (NPRN 33025) was established for the quarry workers and their families. Remains of Porth y Nant quarry include buildings, a tramway incline and jetty.

B.A.Malaws, RCAHMW, 07 March 2006.