Hampshire Basin

The Hampshire Basin is a geological basin of Palaeogene age in southern England, underlying parts of Hampshire, the Isle of Wight, Dorset, and Sussex. Like the London Basin to the northeast, it is filled with sands and clays of Paleocene and younger ages and it is surrounded by a broken rim of chalk hills of Cretaceous age.

The Hampshire Basin is the traditional name for the landward section of a basin underlying the northern English Channel and much of central southern England, known more fully as the Hampshire-Dieppe Basin. It stretches a little over 100 miles (160 km) from the Dorchester area in the west to Beachy Head in the east. Its southern boundary is marked by a monocline, the Purbeck Monocline, resulting in a near-vertical chalk ridge which forms the Purbeck Hills of Dorset, running under the sea from Old Harry Rocks to The Needles and the central spine of the Isle of Wight and continuing under the English Channel as the Wight-Bray monocline. The northern limit is the chalk of the South Downs, Salisbury Plain and Cranborne Chase. The basin at its widest is around 30 miles (48 km) from north to south between Salisbury and Newport. The area west of the River Avon is usually known as the Poole Basin.

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