Gallery of Sedimentary Structures

Bedforms and Cross-Stratification Produced by Currents

Bedforms are structures that are moulded on beds where deposition is taking place. Current-produced bedforms are diverse, and are useful indicators of depositional processes. Most bedforms migrate over the sediment surface. As a result, sediments deposited by bedforms typically show cross-stratification. The selection shown here includes both views of bedforms, and views of cross-stratification in strata deposited in bedforms.
Images copyright © 1998, John W.F. Waldron, except where otherwise stated
linguoid ripples Linguoid current ripples, Kennetcook River
straight ripples Straight-crested current ripples, Cambrian sandstone, Moraine Lake, Alberta
climbing ripple cross-lamination Cross-lamination produced by current ripples, Quaternary fluvioglacial sands, Lothian, Scotland. The cross-lamination here includes both 'normal' (non-climbing) cross-sets and climbing-ripple cross-lamination.
dunes Lunate (crescent-shaped) dunes in sand and gravel, Kennetcook River.
dune Straight-crested dunes, also know as sand waves. Kennetcook River estuary, Nova Scotia
trough cross-bed Tough cross-bed, characteristic of deposition in lunate dunes. Wolfville Formation (Triassic), Nova Scotia
trough cross-bed Tabular cross-beds, Goldenville Formation, Guysboro County NS.
trough cross-bed Tabular cross-bedding produced by eolian dunes, Wolfville Formation, Red Head NS (Photo © David R. Brown)
Antidunes Antidunes beneath fast-flowing stream, Kennetcook River. Flow is from left to right, but antidunes were visibly migrating slowly from right to left.
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