Northumberland role in the Industrial Revolution from the 18th century on. Many coal mines operated in Northumberland until the widespread closures in the 1970s and 1980s. Collieries operated at Ashington, Bedlington, Blyth, Choppington, Netherton, Ellington and Pegswood. The region's coalfields fuelled industrial expansion in other areas of Britain, and the need to transport the coal from the collieries to the Tyne led to the development of the first railways. Shipbuilding and armaments manufacture were other important industries before the deindustrialisation of the 1980s. Northumberland remains largely rural, and is the least-densely populated county in England. In recent years the county has
San Mateo County, California spur of the Santa Cruz Mountains that run through the county. The northern and north-east parts of the county are very heavy densely populated with largely urban and suburban areas, with many of its cities as edge-cities for the Bay Area, whilst the deep south and the west central parts of the county are less heavy densely populated with more rural environment and coastal beaches areas. San Mateo County straddles the San Francisco Peninsula, with the Santa Cruz Mountains running its entire length. The county encompasses a variety of habitats including estuarine, marine, oak woodland, redwood forest, coastal scrub and