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Climate signals from Hoxne

A new paper by Prof David Horne and colleagues sheds further light on the ‘Arctic Bed’ at Hoxne

The name ‘Hoxne’ has a special place in the lexicon of Palaeolithic archaeology. The brickyard and adjacent pits located near the village of Hoxne in northeast Suffolk have long been famous for John Frere’s discovery in 1797 of several “objects of curiosity”, which later become known as handaxes, and the recognition of their antiquity and significance. More recently John Wymer’s systematic excavations at the site in the 1970s provided a detailed account of the geology, environment and archaeology at the site. It is also an important site for Quaternary geology and biology more generally; Richard West’s classic work on the palaeobotany, published in 1956, provided a detailed assessment of the interglacial vegetation history at Hoxne, and was the basis of the formal definition in 1973 of the Hoxnian Stage of the British Pleistocene. This interglacial is now generally correlated with Marine Isotope Stage (MIS) 11 of the ocean record which dates to around 425,000 to 360,000 years ago.

Schematic section through the Quaternary deposits at Hoxne. The Hoxnian interglacial is represented by strata E-D and the cold interval by Stratum C.

A perhaps less well remembered but no less noteworthy contribution to research at Hoxne is that of Clement Reid (1853-1916). Reid, a geologist and palaeobotanist, and officer of the Geological Survey, is known for his detailed mapping and description of the Quaternary deposits in Britain and elsewhere, and, with his wife Eleanor, was one of the pioneers of the use of plant macrofossils to reconstruct past vegetation changes. Reid directed excavations at Hoxne in 1895 on behalf of the British Association. This work laid the foundations for understanding the site, and established the stratigraphic succession of a series of lacustrine clays (bed E), peat (bed D) and overlying lacustrine and fluvial sediments (beds C-A). Reid identified macrofossils of dwarf species of birch and willow in Bed C, hence the term the ‘Arctic bed’ for this part of the succession, which he regarded as being deposited during a period of cold climate conditions following the main part of the interglacial and succeeded by a further phase of temperate climate conditions when beds A and B were deposited.

A 50cm monolith through part of Stratum C at Hoxne, sampled during AHOB excavations in 2003
A 50cm monolith through part of Stratum C at Hoxne, sampled during AHOB excavations in 2003

One hundred and twenty-five years later, the Hoxne succession has again been investigated for its fossil content and palaeoclimatic significance. A new paper by Dave Horne and colleagues published in Quaternary Research provides quantitative palaeotemperature estimates from three invertebrate fossil groups; beetles, chironomids and ostracods, which are found within the Hoxne deposits, including Stratum (=Reid’s Bed) C. Using the results from the Beetle Mutual Climate Range (BMCR), the Chironomid Transfer Function (CTF) and the Mutual Ostracod Temperature Range (MOTR) methods, a multi-proxy consensus approach was used to reconstruct the temperature variations during the deposition of the Hoxne succession. The results indicate that summer temperatures during the Hoxnian interglacial were similar or up to 4oC higher and winter temperatures were similar or up to 3oC lower than today. In contrast the temperature reconstruction for Stratum C indicates summer temperatures 2.5oC cooler and winter temperatures between 5-10oC cooler than today. A return to more temperate conditions after the deposition of Stratum C, completes the warm-cold-warm oscillation represented at Hoxne. This climate signal can be correlated with sub-stage variations within MIS 11 of the deep ocean record and also provides a palaeoclimatic backdrop for human occupation of the site some 385,000 years ago.

The paper is not available under OA. However, it will be available on QMRO in due course.