Skip to main content
[ "article:topic", "authorname:dsumner" ]
Geosciences LibreTexts

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

    XStrat.jpg

    Ancient Planar Cross Stratification

    RedRockBarStrat.jpg

    Single set of cross strata in a planar bed


    Return to Sedimentary Structures

    Trough Cross Stratification

    TroughXStrat3.jpg

    TroughXStrat2.jpg

    TroughXStrat.jpg

    Ancient Trough Cross Stratification

    TroughMap.jpg

    Plan or Map View of Ancient Trough Cross Stratification


    Return to Sedimentary Structures

    Herringbone Cross Stratification

    HerringboneXStrat.jpg


    Return to Sedimentary Structures

    Hummocky Cross Stratification

    HummockyXStrat.jpg

    HCS.jpg


    Return to Sedimentary Structures

    Cross Stratification from Bar Migration

    FluvialXStrat.jpg

    FluvialXStrat2.jpg

    Recent Alluvial Deposits (Terrace at Redrock State Park, CA)

    AKRiverBarXStrat.jpg

    Recent Fluvial Deposits (Alsek River, Alaska)

    FluvialX2.jpg

    Stratification Due to Bar Migration

    FluvialX1.jpg

    Same outcrop as above, but also showing channel fill deposits above the sandstones deposited by the bar.

    OHRiverXStrat.jpg

    Quarry wall showing fluvial cross stratification, probably due to channel migration and bar accretion.​​​​​​​

    OHRiverXStrat2.jpg

    Extension of the same quarry wall as above


    Return to Sedimentary Structures

    Dune Cross Stratification

    (that does not fit nicely into a specific category)

    OHClimbingDune.jpg

    Climbing Dunes

    DuneXstrat.jpg

    Ancient Dune Cross Stratification

    GravelXstrat.jpg

    Cross Stratified Gravel

    VasquezGradedBedding.jpg

    Graded bedding with faint cross stratification deposited in a fluvial channel

    PebbleChannelXStrat.jpg

    PebbleDuneXStrat.jpg

    Cross stratification in a channel fill in a subaqueous turbidite fan


    Return to Sedimentary Structures

    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

    OHDuneChannelXStrat2.jpg

    Large Cross Stratification

    OHUpBar2.jpg

    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

    Different view of the bedform in the previous photo​​​​​​​


    Return to Sedimentary Structures

    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

    Lake shoreline terraces from the lake

    AKSandWaves4.jpg

    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

    Remnants of giant dunes that migrated during the flood

    AKSandWaves.jpg

    AKSandWaves2.jpg

    Large dune cross stratification and remnants of giant dunes​​​​​​​


    Return to Sedimentary Structures