By the time production peaked during World War I, 10 mines employed 2,000 miners and produced 1 million tonnes of coal annually.
baɪ ðə tˈaɪm pɹədˈʌkʃən pˈiːkt dˈʊɹɹɪŋ wˈɜːld wˈɔːɹ ˈaɪ, tˈɛn mˈaɪnz ɛmplˈɔɪd tˈuː,zˈiəɹoʊzˈiəɹoʊ zˈiəɹoʊ mˈaɪnɚz ænd pɹədˈuːst wˈʌn mˈɪliən tˈʌnz ʌv kˈoʊl ˈænjuːəli.