London Basin

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London Basin

marine basin, Europe

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June 30, 2026

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The London Basin is a geological feature in southeastern England characterized by a shallow trough of bedrock. This basin is primarily composed of Tertiary, Cretaceous, and Jurassic rocks, with a significant layer of London Clay up to 132 meters thick. The basin is bordered by chalk formations: the North Downs to the south and the Chiltern Hills to the north. Beneath the clay lies a stable foundation of older Paleozoic rocks. The surface of the basin is covered by deposits of gravel and brick earth, with modern London built upon centuries of accumulated human-made ground. The River Thames flows through this basin, with its valley featuring gravel terraces that have influenced the city's development.123

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Tertiary Period
Sedimentary sequences
The marine Hampshire and London basins, the Paris Basin, the Anglo-Belgian Basin, and the North German Basin have become the standard for comparative studies of the Paleogene part of the Cenozoic, whereas the Mediterranean region (Italy) has become the standard for the Neogene. The Tertiary record of the Paris…
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The marine Hampshire and London basins, the Paris Basin, the Anglo-Belgian Basin, and the North German Basin have become the standard for comparative studies of the Paleogene part of the Cenozoic, whereas the Mediterranean region (Italy) has become the standard for the Neogene. The Tertiary record of the Paris…
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London
Geologic foundation
The London Basin is a wedge-shaped declivity bounded to the south by the chalk of North Downs, running north to south, and to the north by the chalk outcrop of the Chiltern Hills, running up in a northeasterly direction from the Goring Gap. The chalk floor…
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The London Basin is a wedge-shaped declivity bounded to the south by the chalk of North Downs, running north to south, and to the north by the chalk outcrop of the Chiltern Hills, running up in a northeasterly direction from the Goring Gap. The chalk floor…
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Hertfordshire
…sands and gravels of the London Basin have been extensively worked, creating a series of flooded pits used now for recreation or for water storage. The gently rolling countryside is well wooded and attractive but has been increasingly occupied by the encroaching suburban development of London. The Green Belt legislation…
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…sands and gravels of the London Basin have been extensively worked, creating a series of flooded pits used now for recreation or for water storage. The gently rolling countryside is well wooded and attractive but has been increasingly occupied by the encroaching suburban development of London. The Green Belt legislation…
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United Kingdom
The lowland zone
…and clays, now floor the London and Hampshire basins. The former, an asymmetrical synclinal (or structurally downwarped) lowland rimmed by chalk, is occupied mainly by gravel terraces and valley-side benches and has relatively little floodplain; the latter is similarly cradled by a girdle of chalk, but the southern rim, or…
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…and clays, now floor the London and Hampshire basins. The former, an asymmetrical synclinal (or structurally downwarped) lowland rimmed by chalk, is occupied mainly by gravel terraces and valley-side benches and has relatively little floodplain; the latter is similarly cradled by a girdle of chalk, but the southern rim, or…
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