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The "Finchley Gap" is a location centred on Church End, Finchley, in north London, England. As a topographical feature approximately eight kilometres wide, lying between higher ground to the north-west and to the south-east , it has probably existed for the last one million years or more.
The Finchley Gap has lower ground to the north-east , and the south-west. The North Circular Road passes over the Gap, from one catchment area to the other.
The geolgical history of the Finchey Gap, and its place in the history of academic research, makes it one of the most interesting topographical features of the London area.
The principal geological formation in the Finchley Gap region, as in much of the London Basin, is Eocene London Clay. This is mostly a stiff blue-brown clay, over 100 metres thick. In parts of this region, a relatively thin, upper part of the London Clay formation, sandier in content and known as the Claygate Beds, is also found. In certain areas of relatively limited extent, such as on the higher parts of Harrow on the Hill, Hampstead and Highgate, the London Clay and Claygate Beds are overlain by sandy Eocene Bagshot Beds. All these formations are overlain in several areas by much younger Pleistocene formations, as explained below.