Kent's economy is greatly diversified; haulage, logistics, and tourism are major industries. In northwest Kent, industries include extraction of aggregate building materials, printing and scientific research. Coal mining has also played its part in Kent's industrial heritage. Large parts of Kent are within the London commuter belt and its strong transport connections to the capital and the nearby continent make Kent a high-income county. Twenty-eight per cent of the county forms part of two Areas of Outstanding Natural Beauty: the North Downs and The High Weald.