Cromer Forest Bed

The Cromer Forest-bed Formation, sometimes known as the Cromer Forest Bed, is a Pleistocene aged geological formation in Norfolk, England. It consists of river gravels, estuary and floodplain sediments predominantly silt, sand, and muds as well as peat along the coast of northern Norfolk.^[1] The formation records a number of glacial cycles, with deposition occurring in both relatively cold environments during glacial periods,^[2] as well during interglacial periods when the area had a temperate climate.^[3] The Cromer Forest Bed itself varies in age from about 2 to 0.5 million years ago, from the Early Pleistocene to early Middle Pleistocene,^[4] though the most fossiliferous strata, such as the West Runton Freshwater Bed date to towards the end of deposition during the early Middle Pleistocene. The fossiliferous West Runton Freshwater Bed is the type locality for the Cromerian Stage of the early Middle Pleistocene between 0.8 and 0.5 million years ago.^[5] Some fossils from the Cromer Forest Bed likely come from Early Pleistocene layers, though many finds are found out of stratigraphic context.^[6]

Cromer Forest-bed Formation
Stratigraphic range: Early Pleistocene - Middle Pleistocene 2–0.5 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Cromer Forest-bed Formation exposed at the base of the West Runton Cliffs
Type	Geological formation
Unit of	Dunwich Group
Sub-units	Sheringham Member, Runton Member, West Runton Member, and Bacton Member
Underlies	Middle Pleistocene glacial deposits
Overlies	Wroxham Crag Formation or unconformity with Chalk Group
Thickness	around 6 metres (20 ft)
Lithology
Primary	sands and silts
Other	peat, mud, silty marl
Location
Coordinates	52.941°N 1.253°E / 52.941; 1.253
Region	Norfolk
Country	England
Type section
Named for	Cromer
Named by	Clement Reid
Location	The coast of North Norfolk from Weybourne to Happisburgh
Year defined	1882
Country	England

It is about 6 metres (20 ft) thick^[1] and is exposed in cliff section near the village of West Runton.

Paleontology and paleoanthropology

For over a century this formation, named after the local town of Cromer, has been famous for its assemblage of fossil mammal remains, containing the diverse remains of numerous taxa.^[7][8][5][9]

The West Runton Mammoth, a largely complete skeleton of the steppe mammoth (Mammuthus trogontherii) is one of the most best preserved finds found in the West Runton Freshwater Bed.^[10] The oldest human footprints outside Africa, the Happisburgh footprints as well as handaxes and bison bones with cut marks were also found in layers considered to belong to this deposit near Happisburgh, dated to around 1 million to 780,000 years ago.^[4]

Mammals

Carnivorans

Species	Locality	Notes	Image
Panthera gombaszogensis[5]	West Runon Freshwater Bed	Often called the European jaguar and posited to the ancestor of the living American jaguar (Panthera onca)
Panthera fossilis[5][11]	West Runon Freshwater Bed, Pakefield	A close relative of the modern lion (Panthera leo), and one of the largest cats to have ever lived. Ancestor of the Late Pleistocene cave lion (Panthera spelaea). Older publications assigned remains of P. fossilis to P. leo
Felis cf. lunensis[12][5]	West Runon Freshwater Bed	A primitive member of the genus Felis, which includes the domestic cat and its close relatives
Ursus sp.[9]	West Runon Freshwater Bed	Possibly represents brown bears (Ursus arctos) or members of the cave bear lineage
Ursus deningeri[13]	Bacton, Pakefield	Ancestor of the later cave bear (Ursus spelaea)
Canis mosbachensis[5]	West Runon Freshwater Bed	A smaller ancestor of the modern grey wolf (Canis lupus)
Lynx sp.[5]	West Runon Freshwater Bed	A lynx
Crocuta crocuta[5]		Closely related to living African spotted hyenas, have also been attributed to cave hyenas in older works.[14]
Homotherium latidens[5]		A lion-sized saber-toothed cat
Pachycrocuta brevirostris[5]	Bacton, Overstrand	A giant hyena, the largest ever
Lutra simplicidens[12]	West Runon Freshwater Bed	An extinct otter
Pannonictis pliocaenica[12]		An extinct mustelid belonging to the subfamily Ictonychinae
Martes martes[12]		Commonly known as the pine marten, species extant
Mustela nivalis[12]		Commonly known as the least weasel, species extant
Mustela erminea[12]		Commonly known as the stoat, species extant

Ungulates

Species	Locality	Notes	Image
Cervus elaphus[8]		Commonly known as red deer, species extant
Praemegaceros verticornis[8]		A giant deer belonging to the genus Praemegaceros. Sometimes referred to in historical publications as Megaloceros verticornis	A P. verticornis skeleton from Germany
Praemegaceros dawkinsi[8]		A moderately sized deer.
Megaloceros savini[8]		A reindeer-sized deer species	A M. savini-type antler (top right), compared tp that of an Irish elk (M. giganteus)
Dama sp.[8]		An early indeterminate fallow deer
Capreolus capreolus[8]		Commonly known as roe deer, species extant
Cervus rhenanus[8]		A smaller deer with three-pointed antlers
Eucladoceros ctenoides/tegulensis[8]		A giant deer	Antlers of Eucladoceros ctenoides/tegulensis on display in the Netherlands
Eucladoceros tetraceros[8]
Eucladoceros sedgwickii[8]
Cervalces latifrons[8]		A larger ancestor of the modern moose (Alces alces), one of the largest deer ever	Cervalces latifrons antlers on display in Germany
Hippopotamus antiquus[9]		A larger relative of the modern hippopotamus (Hippotamus amphibius)	Specimen on display in Italy
Bison schoetensacki[7]		A primitive bison	Specimen on display in Germany
Sus scrofa[12]	West Runton Freshwater Bed	Commonly known as wild boar, species extant
Stephanorhinus hundsheimensis[12]		A rhinoceros belonging to the extinct genus Stephanorhinus	Skull on display in Germany
Equus cf. suessenbornensis[12]		A stenonine equine
Equus cf. altidens[12]

Proboscidea

Species	Locality	Notes	Image
Mammuthus trogontherii[10]	West Runton Freshwater Bed	Commonly known as the steppe mammoth, known from a mostly complete skeleton, the West Runton Mammoth collected from the West Runton Freshwater bed in 1990.
Mammuthus meridionalis[10]		A more primitive mammoth chronologically earlier than M. trogontherii	Specimen on display in France
Palaeoloxodon antiquus[10]		Commonly known as the straight-tusked elephant, a larger relative of African elephants

Eulipotyphla

Species	Locality	Notes	Image
Sorex runtonensis[12]	West Runton Freshwater Bed	An extinct shrew belonging the genus Sorex
Sorex savini[12]
Sorex cf. minutus[12]		Remains closely resembling and possibly conspecific with the living pygmy shrew (Sorex minutus)
Macroneomys brachygnathus[12]		A large extinct shrew
Neomys newtoni[12]		An extinct water shrew belonging to the genus Neomys
Desmana sp. [12]		A desman related to the living Russian desman (Desmana moschata)
Talpa minor[12]		An extinct mole belonging to the genus Talpa
Talpa europaea[12]		Commonly known as the European mole, species extant
Erinaceus sp.[12]		A hedgehog, closely related to the living European hedgehog (Erinaceus europaeus)

Primates

Species	Locality	Notes	Image
Macaca sylvanus[12]	West Runton Freshwater Bed	Commonly known as the Barbary macaque. Though extinct in Europe (with the exception of Gibraltar), it remains extant in North Africa

Bats

Species	Locality	Notes	Image
Nyctalus noctula[12]	West Runton Freshwater Bed	Known as the common noctule, species extant

Glires

Species	Locality	Notes	Image
Lepus sp.[12]	West Runton Freshwater Bed	A hare
Sciurus whitei[12]		An extinct squirrel belonging to the genus Sciurus, closely related to the living red squirrel (Sciurus vulgaris)
Castor fiber[12]		Commonly known as the Eurasian beaver, species extant
Trogontherium cuvieri[12]		An extinct member of the beaver family Castoridae somewhat larger than living beavers
Cricetus runtonensis[12]		An extinct hamster belonging to the genus Cricetus, related to the living European hamster (Cricetus cricetus)
Cricetulus migratorius[12]		Commonly known as the grey dwarf hamster, species extant
Pliomys episcopalis[12]		A vole belonging to the extinct genus Pliomys
Clethrionomys hintonianus[12]		An extinct vole belonging to the genus Clethrionomys
Mimomys savini[12]		A vole belonging to the extinct genus Mimomys, related to living water voles (Arvicola)
Microtus gregaloides[12]		An extinct vole belonging to the genus Microtus
Microtus arvalidens[12]
Microtus ratticepoides[12]
Apodemus sylvaticus[12]		Commonly known as the wood mouse, species extant

Birds

A variety of birds are known from the Cromer Forest Bed.^[15]

Species	Locality	Notes	Image
Phalacrocorax cf. carbo[12]	West Runton Freshwater Bed	Remains closely resembling and possibly conspecific with the living great cormorant (Phalacrocorax carbo)
Cygnus sp.[12]		A swan
Anser sp.[12]		A goose
Anatinae spp.[12]		Remains of several species of ducks
Grus cf. Grus grus[12]		Remains closely resembling and possibly conspecific with the living common crane (Grus grus)
cf. Gallinula chloropus[12]		Remains closely resembling and possibly conspecific with the living common moorhen (Gallinula chloropus)
Turdus sp.[12]		A thrush
Sturnus sp. [12]		A starling
Corvidae indet[12]		A small bird belonging to the crow family
Passeriformes indet[12]		A perching bird

Amphibians

Species	Locality	Notes	Image
Triturus vulgaris[12]	West Runton Freshwater Bed	Commonly known as the smooth newt, species extant
Triturus sp. nov [12]		An extinct salamander belonging to the genus Triturus
Bufo bufo[12]		Known as the common toad, species extant
Hyla arborea[12]		Commonly known as the European tree frog, species extant
Rana arvalis[12]		Commonly known as the Moor frog, species extant
Pelophylax cf. ridibundus[12]		Remains closely related to the living marsh frog (Pelophylax ridibundus), recorded under the synonymous name Rana (ridibunda) sp.
Rana temporaria[12]		Known as the common frog, species extant
Rana cf. dalmatina[12]		Remains closely resembling and possibly conspecific with the living agile frog (Rana dalmatina)

Reptiles

Species	Locality	Notes	Image
Anguis fragilis[12]	West Runton Freshwater Bed	Commonly known as the slow worm, species extant
Natrix natrix[12]		Commonly known as the grass snake, species extant
Vipera berus[12]		Commonly known as the adder, species extant

Fish

Species	Locality	Notes	Image
Esox lucius[12]		Commonly known as the Northern pike, species extant
Perca fluviatilis[12]		Commonly known as the European perch, species extant
Tinca tinca[12]		Commonly known as the tench, species extant
Abramis bjoerkna[12]		Commonly known as the white bream, species extant
Scardinius erythrophthalmus[12]		Known as the common rudd, species extant
Rutilus rutilus[12]		Known as the common roach, species extant
Leuciscus idus[12]		Commonly known as the ide, species extant
Anguilla anguilla[12]		Commonly known as the European eel, species extant
Gasterosteus aculeatus[12]		Commonly known as the three-spined stickleback, species extant

Insects

A variety of beetles are known from the Cromer Forest Bed, including the West Runton Freshwater Bed, representing a temperate climate,^[16] and from Sidestrand, representing a cold glacial climate.^[2]

Flora

Pollen and macrofossils from the West Runton Freshwater Bed indicates the presence of a variety of plants at the time of deposition, representing a forest and wetland environment with a temperate climate near to the North Sea coast.^[3]

Species	Locality	Notes	Image
Alnus glutinosa	West Runton Freshwater Bed	Commonly known as European alder, species extant
Betula		Commonly known as birch
Plantago major		Commonly known as broadleaf plantain, species extant
Urtica dioica		Commonly known as stinging nettles, species extant
Picea sp.		Commonly known as spruce
Heracleum sphondylium		Commonly known as hogweed, species extant
Stellaria media		Commonly known as chickweed, species extant
Schoenoplectus lacustris		Known as the common club-rush, species extant
Sparganium erectum		Known as the simplestem bur-reed, species extant
Typha sp.		Commonly known as bullrush or cattail
Bidens tripartita		Known as the three-lobe beggarticks, species extant
Epilobium cf. hirsutum		Commonly known as the great or hairy willowherb, species extant
Eupatorium cannabinum		Commonly known as the hemp-agrimony, species extant
Ajuga reptans		Commonly known as the bugleherb, species extant
Thalictrum flavum		Commonly known as the yellow meadow-rue, species extant
Cyperus fuscus		Commonly known as the brown galingale, species extant
Eleocharis palustris		Known as the common spike-rush, species extant
Juncus sp.		Indeterminate rushes
Persicaria lapathifolia		Known by several common names including pale persicaria and pale smartweed, species extant
Potentilla sp.		Commonly known as cinquefoils
Ranunculus		Includes indeterminate members of the subgenera Ranunculus subgenus Ranunculus and Batrachium
Azolla filiculoides		An aquatic fern. Became extinct in Europe during the Pleistocene, but was reintroduced to the region in historic times
Hydrocharis morsus-ranae		Commonly known as the European frog-bit, species extant
Nuphar lutea		Commonly known as the yellow water-lily, species extant
Nymphaea alba		Commonly known as the white water-lily, species extant
Stratiotes aloides		Commonly known as the water soldier, species extant
Ceratophyllum demersum		Commonly known as hornwort, species extant
Groenlandia densa		An aquatic plant, species extant
Chara sp.		An alga
Rubus idaeus		Commonly known as the red raspberry, species extant
Rabelera holostea		Commonly known as the greater stitchwort, species extant. Labelled in study under previous name Stellaria holostea
Oxybasis cf. rubra		Commonly known as the red goosefoot, species extant. Labelled in study under previous name Chenopodium rubrum
Salix sp.		Commonly known as willow, represented by pollen
Corylus		Commonly known as hazel represented by pollen
Pinus		Commonly known as pine, represented by pollen
Quercus		Commonly known as oak, represented by pollen
Ulmus		Commonly known as elm, represented by pollen
Polypodium vulgare		Known as the common polypody, species extant, represented by spores
Pteridium aquilinum		Commonly known as bracken, species extant, represented by spores
Anemone		Commonly known as windflowers, represented by pollen
Mercurialis perennis		Commonly known as dogs mercury, species extant
Aster		Represented by pollen
Centaurea scabiosa		Commonly known as greater knapweed, represented by pollen
Cirsium/Carduus		Commonly known as thistles, represented by pollen
Anthemis		Commonly known as camomile, represented by pollen
Taraxacum		Commonly known as dandelions, represented by pollen
Hypericum perforatum		Commonly known as St. John's wort, represented by pollen
Plantago lanceolata		Commonly known as ribwort, represented by pollen
Rumex acetosa		Commonly known as sorrel, represented by pollen
Vicia/Lathyrus		Pollen representing either vetches, peavines, or both
Capsella		Commonly known as sherpard's purse, represented by pollen
Sinapis		Commonly known as mustard, represented by pollen
Rumex crispus		Commonly known as curly dock, represented by pollen
Persicaria maculosa		Commonly known as lady's thumb, represented by pollen
Plantago maritima		Commonly known as sea plantain, represented by pollen
Armeria		Commonly known as thrifts, represented by pollen
Ballota nigra		Commonly known as black horehound, species extant
Poaceae		Unidentified grass pollen

See also

• Cromerian Stage
• Pakefield
• Red Crag Formation