OverstrandGlacial Till
Glacial Sand and Gravel
Wroxham Crag Formation
Cromer Forest-bed Formation
Alluvial sand and gravel
White Chalk Group
Lower Cretaceous Sandstone
Lias Mudstone
Mercia Mudstone
Sherwood Sandstone Group
Metamorphosed Mudstone, Siltstone and SandstoneSi
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West Runton CliffsPhotographofthecliffsatWestRuntonbeach,highlightingthemajorgeologicalformations.©MartinWarren
Key
ExaggeratedreliefgeologicalmapofCromerandthesurroundingarea.ShowingtheCromerRidge,whichatabout100metresabovesealevel,isthehighestpointinthewholeofNorfolk.
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Sheringham
Weybourne
Telegraph Hill
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Overstrand Chalk RaftThehugechalkrafts
thatdominatethecliffsatOverstrand.
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White Chalk
Wroxham Crag Formation
Beach Sand and Gravel
Glacial Till
Cromer Forest-bed Formation
GeologicalMapoftheCromerArea
TherocksaroundCromerareofinternationalimportance,notleastbecausetheCromerForest-bedFormationatWestRuntonisthe‘typelocality’fortheCromerian Stage.TheChalkandCrag depositswhichcanbeseenalongthebeachesofNorthNorfolkarealsoofworldimportance.Abovethesesedimentshowever,aretheglacial depositswhichwerelaiddownstartingapproximately500,000yearsago,duringtheIceAge.TheseformmostofthecliffsthatyoucanseealongthecoastatTrimingham,SidestrandandOverstrand.
TheCromerRidgeisahugeglacialfeaturewhichformsthehighestpointinNorfolk.Theridgeiswhat’sleftoftheterminal moraine,formedastheglacierretreated.Theeasternpartoftheridgeisapush moraine.ThisisbestseenatOverstrand,whichhasa60metrecross-sectionthroughtheridge,showingspectacular‘rafts’ofchalkwhichwerepushedintotheircurrentpositionbyglacialmovement.
Thewesternpartoftheridgeiscomposedofoutwashsandsandgravelsdepositedbyriversattheglacieredge.ThisisbestseenatTelegraphHill.Attheviewpointthereisasteepnorthward-facingslopewhichwouldhavebeentheglaciermargin,thisrestsontheflat-lyingoutwashgravelsurfaceofKellingHeath.TherearealsoaseriesofcircularhillsknownaskamesbetweenTelegraphHillandthesea.
Glossary:
Cromerian Stage =astagewithinthePleistocenePeriod,from866,000to478,000yearsago.
Crag deposits =aseriesofmarinedepositsatthebaseofthePleistoceneinNorfolk,SuffolkandEssex.Cragisalocalwordforshellysand.
Glacial deposits =therocks,soilandothersedimentpickedupandtransportedbyglaciers.
Terminal moraine =sedimentsdepositedbyaglacieratitsendwhentheicewasatitsmaximumextent.
Outwash =glacialsedimentsdepositedbymeltwaterattheterminusofaglacier.
Push moraine =abroadarc-shapedridgeofmaterialpushedalongbyanadvancingglacier.
Kame =sandandgravelhillsformedasglaciers.retreat.
www.museums.norfolk.gov.uk
Geology Gallery
IcecoverageintheBritishIslesduringthemostrecentglaciation(betweenabout110,000to10,000yearsago).TheCromerRidgeisonefeaturecausedbythemovementoficeduringthisglaciation.