TrekGEO > Geology of Japan > Sedimentary facies > Tidal flat

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Tidal flat

Depth of water

High tide - Ebb tide

Circumstances

Formed at the tidal zones at the inner bays and inner lagoons where the differeces of tidal level are large. Subjected to the little influences of waves. Sands are supplied during rising and pulling tides, and mud is supplied during the slack water such as high tide. 2 pairs of sand an mud beds corresponds to the 2 tides in a day. Tides in the tidal flats flow in the tidal channels.

Sedimentary facies (Sediments)

Finely interbedded sands and mud. Massive fine sands and massive silt.

Sedimentary facies (Sediments, Reef)

Lime-mudstone, Dolo-mudstone, Bioclastic wackestone, Bioclastic packstone, Peloidal grainstone, Dolomite

Sedimentary facies (Structures)

No graded bedding by the strong bio-turbation. Double mud drapes in sandstones. Wave ripples. Cross stratifications associated with mud drapes and herringbone cross-stratifications in tidal channels.

Facies fossils

Trace fossils of crabs such as Ocypodidae

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