Cromerian Interglacial

The arctic climate of the early Pleistocene gave way to milder conditions which favoured the growth of pine (Pinus) and birch (Betula) then more temperate species such as oak (Quercus), lime (Tilia), elm (Ulmus)and hazel (Corylus) forest. European Larch (Larix decidua) is known only from this period before its introductionas a forestry tree in recent times.

Early Cromerian Pine and Birch habitat

Until recently it was generally believed that the Cromerian represented a single temperate event. It is now apparent that sites of Cromerian age correspond to a much greater span of time than originally thought (ca. 780,000-450,000 BP) with flucutuations between cold and temperate climates. Mollusc assemblages, indicator mammal and plant species, and what is believed to be a Water Vole evolutionary line have been used to construct an argument for the presence of up to seven distinct temperate events within the Cromerian.

In the Midlands, during the Cromerian, instead of the Warwickshire Avon the long since disappeared Bytham River drained from the southwest Midlands and the Pennines through Warwickshire and parts of Leicestershire before turning south through mid-East Anglia and eventually eastwards into what is now the North Sea but was then dry land. The Bytham was probably one of the most important routes of colonisation for Britain’s first human inhabitants. Several important archaeological sites lie along the route of this lost river.

The recent discovery of worked flints at Pakefield in Norfolk, which were found in association with Bytham River deposits have possibly pushed back the record of human habitation in the British Isles, and indeed Northern Europe, to the early Cromerian some 700,000 years ago. It is possible that these tools represent the handiwork of the ancient human, Homo antecessor. Other River Bytham related sites include High Lodge and Warren Hill in Norfolk and Waverley Wood near Coventry in Warwickshire.

The other major colonisation route was along the south coast of Britain and is best represented by the famous site of Boxgrove in West Sussex. The lower part of the Thames at this time flowed to the north of its current course, but there is as yet no evidence of colonisation along it at this early time. In Herefordshire there are traces of a lost river called the Mathon, but again as yet no archaeological evidence of human activity has been found.

The faunas of the Cromerian Upper Freshwater Bed at West Runton (Norfolk coast) and the Sugworth interglacial deposits (near Oxford) contain three extinct Freshwater mollusc spp. (Pisidium clessini, Valvata goldfussiana and Tanousia runtoniana). The beds at Sidestrand (Norfolk) contain V. naticina instead. The terrestrial invertberate fauna was however very like the modern British one.

The mammalian fauna included two species of mole, Russian Desman (Desmana moschata), two species of beaver (Trogontherium cuvieri and Castor fibia), Common Hamster (Cricetus cricetus), a vole (Microtus oeconomus), Hazel Dormouse (Muscardinus avellanarius), Spotted Hyaena (Crocuta crocuta), Ancestral Wolf (Canis mosbachensis), Archaic Cave Bear (Ursus deningeri), Macaque (Macaca sylvanus), European Jaguar (Panthera gombaszoegensis), European Hunting Dog (Xenocyon lycanoides), Mink (Mustela lutreola), Badger (Meles meles), Lion (Panthera leo) and Red (Cervus elaphus), Roe (Capreolus capreolus) and Fallow (Dama dama) deer, the extinct deer Megaloceras verticornis & Alces latifrons, Wild Boar (Sus scrufo), Aurochs (Bos primigenius), an extinct Bison (Bison schoetensacki), Etruscan Rhinoceros (Stephanorhinus hundsheimensis) and a Horse (Equus sp.). The impressive remains of a Steppe Mammoth (Mammuthus trogontherii) found at West Runton date to the Cromerian. The Steppe Mammoth was descended from the Ancestral Mammoth (M. meridionalis) and was the ancestor of the Woolly Mammoth (M. primigenius). As the climate cooled at the end of the Cromerian two lemmings appeared. The Common Hamster, now a steppe animal, is known to have inhabited oak woodland duing the Cromerian. The Vole Mimomys savini was replaced by the Water Vole (Arvicola terrestris cantiana) during this period.

Red Deer

One particular site, Boxgrove, near Chichester, West Sussex, has yielded a large bone assemblage, including 45 species of mammal. There were 11 now extinct species and 12 species that are no longer extant in the UK. The species included 2 shrews (Sorex runtonensis, S. savini), Mountain Hare (Lepus timidus), 3 voles (Pliomys episcopalis, Microtus gregalis and A. terrestris cantiana), a mouse (Apodemus maastrichteinsis), Ancestral Wolf, the deer Megaloceras verticornis and M. dawkinsi, Etruscan Rhinoceros, Horse (Equus caballus) and Archaic Cave Bear, Fish and amphibians, such as the Common Frog (Rana temporaria), Flounder and Salmon (Salmo salar) were present as were large birds, such as the Great Auk (Pinguinus impennis), goose (Anser sp.)and Tawny Owl (Strix aluco), and smaller birds, like the Robin (Erithacus rubecula), Starling (Sturnus vulgaris)and Grey Partridge (Perdix perdix). In addition to the mammalian fauna evidence was found of human artifacts and butchery, and ‘Boxgrove Man’ (Homo heidelbergensis), the oldest human in UK. The fauna found at Boxgrove, at the level of the hominid finds, are consistent with a warm interglacial climate.

Homo heidelbergensis

Boxgrove Man lived at the end of the Cromerian, between 480,000 and 426,000 years ago (although recent evidence points to nearer 400,000 year ago i.e. at the end of the Hoxnian Interglacial). His remains consist of a leg bone, gnawed at both ends by a carnivore, and two teeth. They are evidence for an extraordinarily tall and robust adult male. Cut marks on associated horse (Equus), rhinoceros and bear bones from Boxgrove were made by flint tools, and show that Boxgrove Man’s contemporaries were skinning, disarticulating and defleshing carcasses at the site, prior to the bones being smashed open to extract their marrow. Some of the bones and deer antler were subsequently modified and used as tools to work flint.

The deposits at Waverley Wood Farm quarry pit, near Bubbenhall in Warwickshire were formed by the River Bytham. The deposits contain handaxes made of andesitic volcanic ash from the Lake District that are broadly contemporary with those from Boxgrove. The deposits were formed in cooling conditions probably at the end of a temperate stage. The plant remains included conifer cones and needles and seeds of water crowfoot (Ranunculus sp.), sedges and duckweed (Lemna sp).. Pollen of all these species also occurred along with that of alder (Alnus sp.) and birch from the trees, and grass, Compositae (daisy and dandelion family) and reeds from the herbaceous plants. Together the pollen and the plant macro remains show that the river ran through a landscape of coniferous forest with some areas of open grassy land. Among the finds in the quarry were teeth and bones of Straight-tusked Elephant (Palaeoloxodon antiquus) in addition to horse, bison and deer among the large mammals, and voles, moles and shrews among the smaller ones. The insect fauna consisted of 200 species that reflect all of the environments suggested by the plants and mammals and also indicate summer temperatures of around 15° C and winters between 3 and –5° C. Both of these values are slightly colder than the Midlands at the present day. The mollusc fauna confirms the climate indications of the other fossils, although the bivalve species Unio crassus suggest a more continental climate that that of the modern Midlands.

.....................

...............................................................................................Straight-tusked Elephant Teeth