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.