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Subaqueous Bedforms and Cross Stratification

  • Page ID
    4141
  • I have divided these by type of bedform and cross stratification. The examples are both fluvial and marine.

    Planar Cross Stratification

    PlanarXstrat.jpg

    Figure \(\PageIndex{1}\): Ancient Planar Cross Stratification

    XStrat.jpg

    Figure \(\PageIndex{2}\): Ancient Planar Cross Stratification

    RedRockBarStrat.jpg

    Figure \(\PageIndex{3}\): Single set of cross strata in a planar bed


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    Trough Cross Stratification

    TroughXStrat3.jpg

    Figure \(\PageIndex{4}\): Ancient Trough Cross Stratification

    TroughXStrat2.jpg

    Figure \(\PageIndex{5}\): Ancient Trough Cross Stratification

    TroughXStrat.jpg

    Figure \(\PageIndex{6}\): Ancient Trough Cross Stratification

    TroughMap.jpg

    Figure \(\PageIndex{7}\): Plan or Map View of Ancient Trough Cross Stratification


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    Herringbone Cross Stratification

    HerringboneXStrat.jpg

    Figure \(\PageIndex{8}\): Herringbone cross stratification


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    Hummocky Cross Stratification

    HummockyXStrat.jpg

    Figure \(\PageIndex{9}\): Hummocky cross stratification

    HCS.jpg

    Figure \(\PageIndex{10}\): Hummocky cross stratification


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    Cross Stratification from Bar Migration

    FluvialXStrat.jpg

    Figure \(\PageIndex{11}\): Recent Alluvial Deposits (Terrace at Redrock State Park, CA)

    FluvialXStrat2.jpg

    Figure \(\PageIndex{12}\): Recent Alluvial Deposits (Terrace at Redrock State Park, CA)

    AKRiverBarXStrat.jpg

    Figure \(\PageIndex{13}\): Recent Fluvial Deposits (Alsek River, Alaska)

    FluvialX2.jpg

    Figure \(\PageIndex{14}\): Stratification Due to Bar Migration

    FluvialX1.jpg

    Figure \(\PageIndex{15}\): Same outcrop as above, but also showing channel fill deposits above the sandstones deposited by the bar.

    OHRiverXStrat.jpg

    Figure \(\PageIndex{16}\): Quarry wall showing fluvial cross stratification, probably due to channel migration and bar accretion.

    OHRiverXStrat2.jpg

    Figure \(\PageIndex{17}\): Extension of the same quarry wall as above


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    Dune Cross Stratification

    (that does not fit nicely into a specific category)

    OHClimbingDune.jpg

    Figure \(\PageIndex{18}\): Climbing Dunes

    DuneXstrat.jpg

    Figure \(\PageIndex{19}\): Ancient Dune Cross Stratification

    GravelXstrat.jpg

    Figure \(\PageIndex{20}\): Cross Stratified Gravel

    VasquezGradedBedding.jpg

    Figure \(\PageIndex{21}\): Graded bedding with faint cross stratification deposited in a fluvial channel

    PebbleChannelXStrat.jpg

    Figure \(\PageIndex{22}\): Cross stratification in a channel fill in a subaqueous turbidite fan

    PebbleDuneXStrat.jpg

    Figure \(\PageIndex{23}\): Cross stratification in a channel fill in a subaqueous turbidite fan


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    The following photographs are of large-scale cross stratification that was deposited by the migration of giant dunes and/or large fluvial bars. Detailed analysis of the regional characteristics of these deposits would be required to distinguish between dune and bar deposition in many cases, and both might be present.

    OHDuneChannelXStrat.jpg

    Figure \(\PageIndex{24}\): Large Cross Stratification

    OHDuneChannelXStrat2.jpg

    Figure \(\PageIndex{25}\): Large Cross Stratification

    OHUpBar2.jpg

    Figure \(\PageIndex{26}\): Cross stratified sediment deposited by a migrating bar based on the abundance of more planar laminae that would be characteristic of a channel bottom.

    OHUpBar.jpg

    Figure \(\PageIndex{27}\): Different view of the bedform in the previous photo


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    The following photographs were taken by Jeff Mount during his Roy Shlemon Course in Applied Watershed Science class trip down the Copper River, Alaska and Yukon (see the Shlemon class web page). The river shown below was dammed by ice from the toe of a glacier, which created a very large lake. The ice dam broke catastrophically, producing a huge flood. The flood waters transported very large volumes of sediment in huge dunes. After normal river processes resumed, the river eroded into the flood deposits, exposing the cross stratification in these impressive dunes.

    AKLakeTerraces.jpg

    Figure \(\PageIndex{28}\): Lake shoreline terraces from the lake

    AKSandWaves4.jpg

    Figure \(\PageIndex{29}\): Lake shoreline terraces from the lake and cross stratification in the river bank. This cross stratification may have been deposited by the flood waters.​​​​​​​

    AKSandWaves3.jpg

    Figure \(\PageIndex{30}\): Remnants of giant dunes that migrated during the flood

    AKSandWaves.jpg

    Figure \(\PageIndex{31}\): Large dune cross stratification and remnants of giant dunes​​​​​​​

    AKSandWaves2.jpg

    Figure \(\PageIndex{32}\): Large dune cross stratification and remnants of giant dunes​​​​​​​


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