Gallery of Sedimentary Structures

Erosional structures produced by currents

Images copyright © 1998, John W.F. Waldron, except where otherwise stated
flutes Flute casts in fluvial sandstone, Mabou Group, Lismore NS. Flutes are scoop shaped depressions produced by erosion as a rapid current flows over a cohesive muddy surface. Flute casts (more accurately flute molds) are bulbous structures produced when the current fills the flute with sand.
herringbone cross-bedding Flute casts on base of turbidite bed. Flutes have a bulbous up-current end, and fade down-current. Current flowed toward the bottom right, parallel to the pencil.
grooves Grooves: tool marks produced by dragged objects. These are casts (more accurately molds) of grooves, preserved as ridges on the base of a thick sandstone bed, Goldenville Fm., Liscomb Island, Eastern Shore, NS
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