Giant current ripples

Giant current ripples are active channel topographic forms up to 20 m high, which develop within near-talweg areas of the main outflow valleys created by glacial lake outburst floods. Giant current ripple marks are morphologic and genetic macroanalogues of small current ripples formed in sandy stream sediments.

The giant current ripple marks are important depositional forms in diluvial plain and mountain scablands.

The history of the scabland studies has two distinct stages: the "old" one that began with the first works by J Harlen Bretz and Joseph Pardee in North America and lasted until the end of the 20th century that was crowned with the discovery of giant current ripple marks in Eurasia, and a "new" one. The latter is associated with heated debates concerning the genesis of the relief under study and which involved a lot of Russian geologists, geomorphologists and geographers. The discussion about the origin of the giant ripples dealt at least to a certain extent with every aspect of the diluvial theory, from the genesis of the lakes themselves, their existence duration, possibilities of their cataclysmic failures, etc. to the origin of the diluvial forms - the aspects that have been accepted by many scientists worldwide, including an increasing number of Russian scientists.

J Harlen Bretz, author of the hypothesis of the diluvial origin of the Channeled Scabland, considered mainly "giant gravel bars" (diluvial ramparts and terraces) among the diluvial-accumulative formations as a proof of his case along with the destructive forms of the scabland (gorges-coulees, waterfall cataracts – chains of erosional dry falls washed of loose sediments by the floods of diluvial farewell rocks).

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