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Climbing ripples
When a fluid laden with sediment rapidly drops some of its load as it is flowing, a sedimentary structure named "climbing ripple lamination" can form. It is characterized by superimposed ripple crests (or ripple cross-sets) migrating in the direction of flow. Photo taken at the Varvito Park, Ito, Brazil, with exposures of Permian strata from the Itararé Group. Scale in cm.
Bedforms
Bedforms are morphological patterns that form at the interface of flowing fluid and a bed of moving sediment. Typical examples include dunes and ripples. Lateral migration of bedforms can generate sedimentary structures, like ripple cross-lamination or cross-stratification. Geology students often mix up the concept of bedform and sedimentary structure: ripples are bedforms (not sedimentary structures) and ripple cross-lamination is a sedimentary structure (not a bedform). Sometimes, like in this…