Geology Site Account

Landscape feature of geological interest with potential to promote geology. Disused pits have provided information about the underlying geology. Any further significant excavations in the area should be recorded.

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Site description

Pole Hill is 91 metres (300 feet) above sea level and from the summit there is a fine panoramic view of London. It lies exactly on the Greenwich Meridian and as the summit is visible from Greenwich a granite obelisk was erected in 1824 to mark the direction of true north from the Royal Observatory which enabled geographers to obtain a zero degree bearing. However, when this was recalculated several years later the true meridian was found to be 19 feet east of the obelisk.

The hill consists of London Clay capped by Claygate Beds. South of the obelisk a brickworks was established in the mid-19th century and the pit exposed Claygate Beds consisting of alternating layers of sand and loam that were deposited on the floor of a shallow, subtropical sea. The brickworks was extensive, consisting of six kilns, an engine house, a 100 foot long drying house, and several outbuildings. In 1914 it was reported that another brickworks had opened slightly further down the hill, on land known as Park Hill, and the pit serving these works was of great interest as it yielded septarian nodules from the London Clay which contained numerous fossils. Over 25 species of marine molluscs were found here, including a nautilus, sharks teeth and fossil wood. The nodules also contained radiating crystals of barite and small crystals of selenite were abundant in the clay.

Both brickworks had closed by 1930 and the land on this side of the hill is now occupied by housing. The fossils, which are about 50 million years old, are preserved in the Essex Field Clubs collection (formerly in the Passmore Edwards Museum).