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Callan Bentley's Snapshots

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  1. Marker bed

    Snapshot Title: Marker bed
    Taken by: Callan Bentley

    Image: Conemaugh Group, Corridor H
    Image Owner: Callan Bentley



    Description:

    Prominent thick-bedded sandstone with central coal seam; stained orange. Footwall.



  2. Slip surface

    Snapshot Title: Slip surface
    Taken by: Callan Bentley

    Image: Conemaugh Group, Corridor H
    Image Owner: Callan Bentley



    Description:

    Running through the middle of this snapshot is a slip surface that dips to the left (west) and offsets a prominent orangey-colored massive sandstone double-bed with a coal seam running through the mid...



  3. Road sign

    Snapshot Title: Road sign
    Taken by: Callan Bentley

    Image: Conemaugh Group, Corridor H
    Image Owner: Callan Bentley



    Description:

    Showing distances to towns, headed west.



  4. Attitude change

    Snapshot Title: Attitude change
    Taken by: Callan Bentley

    Image: Conemaugh Group, Corridor H
    Image Owner: Callan Bentley



    Description:

    Big swivel in the orientation of bedding here - close to horizontal at left; gets much steeper to the right.



  5. Channel scour

    Snapshot Title: Channel scour
    Taken by: Callan Bentley

    Image: Conemaugh Group, Corridor H
    Image Owner: Callan Bentley



    Description:

    Sandstone portion is most obvious, but there are subparallel strata below it too.



  6. The Dragon's Tongue

    Snapshot Title: The Dragon's Tongue
    Taken by: Callan Bentley

    Image: Conemaugh Group, Corridor H
    Image Owner: Callan Bentley



    Description:

    Coal bed with forked offshoots



  7. Dan Doctor's rig

    Snapshot Title: Dan Doctor's rig
    Taken by: Callan Bentley

    Image: Conemaugh Group, Corridor H
    Image Owner: Callan Bentley



    Description:

    to serve as a sense of scale



  8. Mitch Blake's rig

    Snapshot Title: Mitch Blake's rig
    Taken by: Callan Bentley

    Image: Conemaugh Group, Corridor H
    Image Owner: Callan Bentley



    Description:

    to serve as a sense of scale



  9. Crenulation in shale

    Snapshot Title: Crenulation in shale
    Taken by: Callan Bentley

    Image: Paleoslump and Fluvial Incision Structures, Conemaugh Group, Corridor H, West Virginia
    Image Owner: Marissa Dudek



    Description:

    Small ~1cm wavelength crinkles in the platy shale.



  10. Recumbent folds

    Snapshot Title: Recumbent folds
    Taken by: Callan Bentley

    Image: Paleoslump and Fluvial Incision Structures, Conemaugh Group, Corridor H, West Virginia
    Image Owner: Marissa Dudek



    Description:

    I noted these recumbent folds (axial plane ~horizontal) in the field.



  11. Sectioned clast

    Snapshot Title: Sectioned clast
    Taken by: Callan Bentley

    Image: Sykesville Formation, Chain Bridge Flats, DC
    Image Owner: Callan Bentley



    Description:

    Exposed on 2 surfaces



  12. Dark-colored clast

    Snapshot Title: Dark-colored clast
    Taken by: Callan Bentley

    Image: Sykesville Formation, Chain Bridge Flats, DC
    Image Owner: Callan Bentley



    Description:

    Long axis included w/in the plane of foliation (late Ordovician Taconian Orogeny)



  13. Small mica-rich clast

    Snapshot Title: Small mica-rich clast
    Taken by: Callan Bentley

    Image: Sykesville Formation, Chain Bridge Flats, DC
    Image Owner: Callan Bentley



    Description:

    w/ reaction halo



  14. Large, mica-rich clast

    Snapshot Title: Large, mica-rich clast
    Taken by: Callan Bentley

    Image: Sykesville Formation, Chain Bridge Flats, DC
    Image Owner: Callan Bentley



    Description:

    bearing a reaction halo around it



  15. Light-colored clast

    Snapshot Title: Light-colored clast
    Taken by: Callan Bentley

    Image: Sykesville Formation, Chain Bridge Flats, DC
    Image Owner: Callan Bentley



    Description:

    Apparently well rounded.



  16. Hammerhead

    Snapshot Title: Hammerhead
    Taken by: Callan Bentley

    Image: Sykesville Formation, Chain Bridge Flats, DC
    Image Owner: Callan Bentley



    Description:

    for scale



  17. Shadow

    Snapshot Title: Shadow
    Taken by: Callan Bentley

    Image: Sykesville Formation, Chain Bridge Flats, DC
    Image Owner: Callan Bentley



    Description:

    of the GigaPan



  18. Fresh vs. weathered surfaces

    Snapshot Title: Fresh vs. weathered surfaces
    Taken by: Callan Bentley

    Image: Sykesville Formation, Chain Bridge Flats, DC
    Image Owner: Callan Bentley



    Description:

    This rock rusts!



  19. Lichen

    Snapshot Title: Lichen
    Taken by: Callan Bentley

    Image: Sykesville Formation, Chain Bridge Flats, DC
    Image Owner: Callan Bentley



    Description:

    Not clasts



  20. Foliated clast

    Snapshot Title: Foliated clast
    Taken by: Callan Bentley

    Image: Sykesville Formation, Chain Bridge Flats, DC
    Image Owner: Callan Bentley



    Description:

    Where the (coarser; gneissic) foliation internal to the clast is oblique to the regional foliation in the surrounding matrix.



  21. Quartz clast

    Snapshot Title: Quartz clast
    Taken by: Callan Bentley

    Image: Sykesville Formation, Chain Bridge Flats, DC
    Image Owner: Callan Bentley



    Description:

    Oblique to foliation.



  22. Hammer for scale

    Snapshot Title: Hammer for scale
    Taken by: Callan Bentley

    Image: Sykesville Formation, Chain Bridge Flats, DC
    Image Owner: Callan Bentley



    Description:

    Here's the top of the hammer handle.



  23. Weathered out clast

    Snapshot Title: Weathered out clast
    Taken by: Callan Bentley

    Image: Sykesville Formation, Chain Bridge Flats, DC
    Image Owner: Callan Bentley



    Description:

    You can see a little tail of relatively-unweathered biotite-rich clast to the right of the joint trace.



  24. Bird poop

    Snapshot Title: Bird poop
    Taken by: Callan Bentley

    Image: Sykesville Formation, Chain Bridge Flats, DC
    Image Owner: Callan Bentley



    Description:

    Probably a heron.



  25. Recessive weathering

    Snapshot Title: Recessive weathering
    Taken by: Callan Bentley

    Image: Sykesville Formation, Chain Bridge Flats, DC
    Image Owner: Callan Bentley



    Description:

    Some clasts are less chemically stable than the surrounding matrix, and weather out to make clast-shaped holes in the rock face.



  26. Another reaction halo

    Snapshot Title: Another reaction halo
    Taken by: Callan Bentley

    Image: Sykesville Formation, Chain Bridge Flats, DC
    Image Owner: Callan Bentley



    Description:

    Rimming this mica-rich clast



  27. Felsic clast

    Snapshot Title: Felsic clast
    Taken by: Callan Bentley

    Image: Sykesville Formation, Chain Bridge Flats, DC
    Image Owner: Callan Bentley



    Description:

    Mica poor, relative to matrix



  28. Reaction halo

    Snapshot Title: Reaction halo
    Taken by: Callan Bentley

    Image: Sykesville Formation, Chain Bridge Flats, DC
    Image Owner: Callan Bentley



    Description:

    Where the clast reacted w/ surrounding matrix.



  29. Fishlike clast

    Snapshot Title: Fishlike clast
    Taken by: Callan Bentley

    Image: Sykesville Formation, Chain Bridge Flats, DC
    Image Owner: Callan Bentley



    Description:

    Pointy tip and frayed tail



  30. Elongate, flat dark schist clasts

    Snapshot Title: Elongate, flat dark schist clasts
    Taken by: Callan Bentley

    Image: Sykesville Formation, Chain Bridge Flats, DC
    Image Owner: Callan Bentley



    Description:

    And chunkier light-colored clasts.



  31. Contrasting clasts

    Snapshot Title: Contrasting clasts
    Taken by: Callan Bentley

    Image: Sykesville Formation, Chain Bridge Flats, DC
    Image Owner: Callan Bentley



    Description:

    Dark-colored, mica-rich clasts tend to be flattened parallel to the plane of foliation. Lighter colored clasts tend to be more chunky and equant.



  32. Sense of scale

    Snapshot Title: Sense of scale
    Taken by: Callan Bentley

    Image: Sykesville Formation, Chain Bridge Flats, DC
    Image Owner: Callan Bentley



    Description:

    Tip of hammer (the only part that's in focus!)



  33. Chlorite clast weathering away

    Snapshot Title: Chlorite clast weathering away
    Taken by: Callan Bentley

    Image: Sykesville Formation, Chain Bridge Flats, DC
    Image Owner: Callan Bentley



    Description:

    more rapidly than surrounding rock.



  34. Fresher surface

    Snapshot Title: Fresher surface
    Taken by: Callan Bentley

    Image: Sykesville Formation, Chain Bridge Flats, DC
    Image Owner: Callan Bentley



    Description:

    The rusty, hydrolysed weathering rind has peeled off here, showing fresher (grayer) rock beneath.



  35. Recessive weathering

    Snapshot Title: Recessive weathering
    Taken by: Callan Bentley

    Image: Sykesville Formation, Chain Bridge Flats, DC
    Image Owner: Callan Bentley



    Description:

    of a chlorite-rich clast



  36. Mafic clast

    Snapshot Title: Mafic clast
    Taken by: Callan Bentley

    Image: Sykesville Formation, Chain Bridge Flats, DC
    Image Owner: Callan Bentley



    Description:

    No reaction rim, though



  37. Slickensides

    Snapshot Title: Slickensides
    Taken by: Callan Bentley

    Image: Sykesville Formation, Chain Bridge Flats, DC
    Image Owner: Callan Bentley



    Description:

    Common feature in these rocks.



  38. Two squashed clasts

    Snapshot Title: Two squashed clasts
    Taken by: Callan Bentley

    Image: Sykesville Formation, Chain Bridge Flats, DC
    Image Owner: Callan Bentley



    Description:

    Ellipsoidal.



  39. Light-colored clasts

    Snapshot Title: Light-colored clasts
    Taken by: Callan Bentley

    Image: Sykesville Formation, Chain Bridge Flats, DC
    Image Owner: Callan Bentley



    Description:

    Some with reaction rims, others (milky quartz) with no obvious reaction rim.



  40. Clast

    Snapshot Title: Clast
    Taken by: Callan Bentley

    Image: Sykesville Formation, Chain Bridge Flats, DC
    Image Owner: Callan Bentley



    Description:

    of milky quartz



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