Geology of Happisburgh
The deposits found at Happisburgh containing artefacts have been named the Hill House Formation, after the Hill House public house, in Happisburgh village, 200 metres from the site and directly above the inland continuation of the ancient river channel. The sediments consist of gravels and estuarine silts laid down by the early river Thames.
Fine-grained estuarine deposits of the early river Thames at Happisburgh. Palaeomagnetic analysis shows that these sediments were deposited during a period of reversed magnetism – when the north and south poles swap. The reversed magnetism, together with a range of plants and now extinct mammals, provide critical evidence suggesting that the artefacts date from between 700,000 and 900,000 years ago. Phil Crabb, Natural History Museum, London