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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. |
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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. |
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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 |