The South Maitland coalfields was the most extensive coalfield in New South Wales until the great coal mining slump of the 1960s. It was discovered by Lieutenant-Colonel William Paterson's party when they were engaged in an exploratory visit to the Hunter River Valley during July 1801. Mention has been made that coal was being mined in the area during the 1840s, and about 1850 an outcrop in the vicinity of Mount Vincent was reported to the authorities. Several years later, Mr. Bourn Russell also known as Captain Russell commenced operations in a small way at Stoney Creek, Homeville (New South Wales), near Farley. The potential wealth of the coalfields was brought forward in 1886 by Professor Tannatt William Edgeworth David who located an outcrop of first grade coal at Deep Creek, near the present township of Abermain. This gentleman was instrumental in having the whole coal-bearing area, estimated at 20,000 acres (81 km²), reserved for mining purposes. The coalfields were subsequently served by the South Maitland Railway which left the New South Wales Government Railways' Great Northern Railway above Maitland at the East Greta Junction, 20 miles 65 chains (33.49 km) north of Newcastle. This railway was in fact a considerable number of lines which all, at some point, merged, but had different original ownerships. On 22 November 1918 the first meeting took place of the South Maitland Railways Proprietary Limited, a company incorporated with a capital of £500,000 in £1 shares, and this company eventually acquired the entire coalfields railway network. The line remains open serving the last remaining Colliery at Pelton. The coalfields roughly commenced at the village of East Greta, about west of Maitland, and stretched all the way to the village of Paxton, south-west of Cessnock, covering numerous villages and towns, and employing tens of thousands of people in over 30 collieries. The two companies which came to dominate the district were Caledonian Collieries Limited, and J & A Brown & Abermain-Seaham Collieries Limited (a merger of three formerly separate companies). These two companies merged in 1960 forming Coal & Allied, that bought Hebburn Co in July 1967. List of collieries and proprietors East Greta No.1 (1891, East Great Coal Mining Co; closed 24 Sept 1929 - Depression) East Greta No.2 (1896, ditto) Glen Greta (1930–1931) Glen Ayr (1914, Glen Ayr Colliery Co.,1930, flooded) Ayrfield No.1, Heddon Greta, (1918–1933, fire) Ayrfield No.2, Heddon Greta, (1924–1930, flooded)