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Callan Bentley's Snapshots

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  1. Fracture

    Snapshot Title: Fracture
    Taken by: Callan Bentley

    Image: Kink banding in Laurel Formation of Rock Creek Shear Zone, Broad Branch, Washington, DC
    Image Owner: Callan Bentley



    Description:

    The orientation of this fracture is about 136°, 80° (right hand rule).



  2. Foliation

    Snapshot Title: Foliation
    Taken by: Callan Bentley

    Image: Kink banding in Laurel Formation of Rock Creek Shear Zone, Broad Branch, Washington, DC
    Image Owner: Callan Bentley



    Description:

    Inside the big kink band, the foliation orientation is 229°, 82° (right hand rule).



  3. Foliation

    Snapshot Title: Foliation
    Taken by: Callan Bentley

    Image: Kink banding in Laurel Formation of Rock Creek Shear Zone, Broad Branch, Washington, DC
    Image Owner: Callan Bentley



    Description:

    Here, the foliation is oriented 185°, 70° (right hand rule)



  4. Pseudomorphs

    Snapshot Title: Pseudomorphs
    Taken by: Callan Bentley

    Image: Klingle Valley metaconglomerate, Laurel Formation, Rock Creek Shear Zone, Washington, DC
    Image Owner: Callan Bentley



    Description:

    Sericite (retrograde) after staurolite (peak)



  5. Highly strained clasts

    Snapshot Title: Highly strained clasts
    Taken by: Callan Bentley

    Image: Klingle Valley metaconglomerate, Laurel Formation, Rock Creek Shear Zone, Washington, DC
    Image Owner: Callan Bentley



    Description:

    These cobbles got MUSHED.



  6. Pseudomorphs

    Snapshot Title: Pseudomorphs
    Taken by: Callan Bentley

    Image: Klingle Valley metaconglomerate, Laurel Formation, Rock Creek Shear Zone, Washington, DC
    Image Owner: Callan Bentley



    Description:

    Sericite-after-staurolite: retrograde metamorphism.



  7. Pseudomorphs

    Snapshot Title: Pseudomorphs
    Taken by: Callan Bentley

    Image: Klingle Valley metaconglomerate, Laurel Formation, Rock Creek Shear Zone, Washington, DC
    Image Owner: Callan Bentley



    Description:

    Sericite after staurolite: retrograde metamorphism.



  8. Pencil for scale

    Snapshot Title: Pencil for scale
    Taken by: Callan Bentley

    Image: Klingle Valley metaconglomerate, Laurel Formation, Rock Creek Shear Zone, Washington, DC
    Image Owner: Callan Bentley



    Description:

    Slightly distorted by the angle of the GigaPan, but each of the black bars along the side of this pencil measure 1 centimeter in length.



  9. Pseudomorphs

    Snapshot Title: Pseudomorphs
    Taken by: Callan Bentley

    Image: Klingle Valley metaconglomerate, Laurel Formation, Rock Creek Shear Zone, Washington, DC
    Image Owner: Callan Bentley



    Description:

    Sericite-after-staurolite: retrograde metamorphism. Note the nice 'fairy cross' near the bottom of this cluster.



  10. Pseudomorphs

    Snapshot Title: Pseudomorphs
    Taken by: Callan Bentley

    Image: Klingle Valley metaconglomerate, Laurel Formation, Rock Creek Shear Zone, Washington, DC
    Image Owner: Callan Bentley



    Description:

    Sericite-after-staurolite: retrograde metamorphism.



  11. Pseudomorphs

    Snapshot Title: Pseudomorphs
    Taken by: Callan Bentley

    Image: Klingle Valley metaconglomerate, Laurel Formation, Rock Creek Shear Zone, Washington, DC
    Image Owner: Callan Bentley



    Description:

    Sericite-after-staurolite: retrograde metamorphism.



  12. Pseudomorphs

    Snapshot Title: Pseudomorphs
    Taken by: Callan Bentley

    Image: Klingle Valley metaconglomerate, Laurel Formation, Rock Creek Shear Zone, Washington, DC
    Image Owner: Callan Bentley



    Description:

    Sericite-after-staurolite: retrograde metamorphism.



  13. cm

    Snapshot Title: cm
    Taken by: Callan Bentley

    Image: Klingle Valley metaconglomerate, Laurel Formation, Rock Creek Shear Zone, Washington, DC
    Image Owner: Callan Bentley



    Description:

    A sense of scale (and distortion!) is provided by this pencil and its 1-centimeter black bars along the side.



  14. Star Trek insignia

    Snapshot Title: Star Trek insignia
    Taken by: Callan Bentley

    Image: Klingle Valley metaconglomerate, Laurel Formation, Rock Creek Shear Zone, Washington, DC
    Image Owner: Callan Bentley



    Description:

    What is up with this fellow?
    -merely flattened and thus a small hollow has become more exaggeratedly concave?
    -sheared with the left side down, creating a "tail"?
    -is it a dismembered fold hinge?



  15. Stretched clast

    Snapshot Title: Stretched clast
    Taken by: Callan Bentley

    Image: Klingle Valley metaconglomerate, Laurel Formation, Rock Creek Shear Zone, Washington, DC
    Image Owner: Callan Bentley



    Description:

    May have "fishmouth" structure at far end - perhaps it was boudinaged? (In that case, a mere axial ratio will underestimate the total strain.)



  16. Pseudomorphs

    Snapshot Title: Pseudomorphs
    Taken by: Callan Bentley

    Image: Klingle Valley metaconglomerate, Laurel Formation, Rock Creek Shear Zone, Washington, DC
    Image Owner: Callan Bentley



    Description:

    Sericite-after-staurolite - retrograde metamorphism.



  17. cm

    Snapshot Title: cm
    Taken by: Callan Bentley

    Image: Klingle Valley metaconglomerate, Laurel Formation, Rock Creek Shear Zone, Washington, DC
    Image Owner: Callan Bentley



    Description:

    A sense of scale is provided by this pencil, which has 1-cm black bars along its side.



  18. Mega-Skolithos

    Snapshot Title: Mega-Skolithos
    Taken by: Callan Bentley

    Image: Tuscarora Sandstone exposed at Hanging Rock Anticline, West Virginia
    Image Owner: Callan Bentley



    Description:

    ((juuuuuuuuuuuuust kidding))



  19. Change in outcrop angle

    Snapshot Title: Change in outcrop angle
    Taken by: Callan Bentley

    Image: Klingle Valley metaconglomerate, Laurel Formation, Rock Creek Shear Zone, Washington, DC
    Image Owner: Callan Bentley



    Description:

    These clasts have not been folded - they are still pancake-like in their geometry, like (most of) their neighbors.



  20. Offset

    Snapshot Title: Offset
    Taken by: Callan Bentley

    Image: Klingle Valley metaconglomerate, Laurel Formation, Rock Creek Shear Zone, Washington, DC
    Image Owner: Callan Bentley



    Description:

    A small fault has offset this foliated clast (top to the left) by an inch or so.



  21. Kinked cobbles?

    Snapshot Title: Kinked cobbles?
    Taken by: Callan Bentley

    Image: Klingle Valley metaconglomerate, Laurel Formation, Rock Creek Shear Zone, Washington, DC
    Image Owner: Callan Bentley



    Description:

    These cobbles appear to have been sheared out and then kinked (top to the left).



  22. Stretched clast

    Snapshot Title: Stretched clast
    Taken by: Callan Bentley

    Image: Klingle Valley metaconglomerate, Laurel Formation, Rock Creek Shear Zone, Washington, DC
    Image Owner: Callan Bentley



    Description:

    This poor cobble has been all smeared out!



  23. Scale

    Snapshot Title: Scale
    Taken by: Callan Bentley

    Image: Klingle Valley metaconglomerate, Laurel Formation, Rock Creek Shear Zone, Washington, DC
    Image Owner: Callan Bentley



    Description:

    This pencil provides a sense of scale. It's slightly out of focuse because it's in a hollow in the rock, but you can still tell that the black bars along the side are 1 centimeter in length.



  24. Stretched clast

    Snapshot Title: Stretched clast
    Taken by: Callan Bentley

    Image: Klingle Valley metaconglomerate, Laurel Formation, Rock Creek Shear Zone, Washington, DC
    Image Owner: Callan Bentley



    Description:

    Like a fish in a school



  25. Lichen

    Snapshot Title: Lichen
    Taken by: Callan Bentley

    Image: Klingle Valley metaconglomerate, Laurel Formation, Rock Creek Shear Zone, Washington, DC
    Image Owner: Callan Bentley



    Description:

    Not a stretched clast.



  26. Internal foliation

    Snapshot Title: Internal foliation
    Taken by: Callan Bentley

    Image: Klingle Valley metaconglomerate, Laurel Formation, Rock Creek Shear Zone, Washington, DC
    Image Owner: Callan Bentley



    Description:

    Some of these clasts have an internal layering: could be sedimentary bedding, or volcanic flow banding, or a preceding generation of metamorphic foliation.



  27. Small fault

    Snapshot Title: Small fault
    Taken by: Callan Bentley

    Image: Klingle Valley metaconglomerate, Laurel Formation, Rock Creek Shear Zone, Washington, DC
    Image Owner: Callan Bentley



    Description:

    This quartzite clast has been offset along a small brittle fracture which must post-date ductile deformation of these clasts.



  28. Stretched clast

    Snapshot Title: Stretched clast
    Taken by: Callan Bentley

    Image: Klingle Valley metaconglomerate, Laurel Formation, Rock Creek Shear Zone, Washington, DC
    Image Owner: Callan Bentley



    Description:

    This one seems to exhibit a sinistral sense of shear on this loose block of float.



  29. A closer look

    Snapshot Title: A closer look
    Taken by: Callan Bentley

    Image: Kink banding in Laurel Formation of Rock Creek Shear Zone, Broad Branch, Washington, DC
    Image Owner: Callan Bentley



    Description:

    For a view of this face, check out this GigaPan shot on the same day:
    gigapan.com/gigapans/128476



  30. Stray fold hinge

    Snapshot Title: Stray fold hinge
    Taken by: Callan Bentley

    Image: Kink banding in Laurel Formation of Rock Creek Shear Zone, Broad Branch, Washington, DC
    Image Owner: Callan Bentley



    Description:

    To get a better view of this face, try another GigaPan shot the same day, but from a different perspective: gigapan.com/gigapans/128419



  31. Kink
  32. Kink

    Snapshot Title: Kink
    Taken by: Callan Bentley

    Image: Kink banding in Laurel Formation of Rock Creek Shear Zone, Broad Branch, Washington, DC
    Image Owner: Callan Bentley



    Description:

    This kink band is at a conjugate angle relative to the big, prominent one a few inchest to the left.



  33. Stretched

    Snapshot Title: Stretched
    Taken by: Callan Bentley

    Image: Kink banding in Laurel Formation of Rock Creek Shear Zone, Broad Branch, Washington, DC
    Image Owner: Callan Bentley



    Description:

    quartzite clast.



  34. 2 kinks and a stretched clast

    Snapshot Title: 2 kinks and a stretched clast
    Taken by: Callan Bentley

    Image: Kink banding in Laurel Formation of Rock Creek Shear Zone, Broad Branch, Washington, DC
    Image Owner: Callan Bentley



    Description:

    A nice little ensemble.



  35. Intense kinking

    Snapshot Title: Intense kinking
    Taken by: Callan Bentley

    Image: Kink banding in Laurel Formation of Rock Creek Shear Zone, Broad Branch, Washington, DC
    Image Owner: Callan Bentley



    Description:

    About an apparent 90 degree angle here between the kink band foliation and the main foliation that surrounds it.



  36. Kink band

    Snapshot Title: Kink band
    Taken by: Callan Bentley

    Image: Kink banding in Laurel Formation of Rock Creek Shear Zone, Broad Branch, Washington, DC
    Image Owner: Callan Bentley



    Description:

    The foliation has been "kinked" in a band about an inch thick.



  37. Kink band

    Snapshot Title: Kink band
    Taken by: Callan Bentley

    Image: Kink banding in Laurel Formation of Rock Creek Shear Zone, Broad Branch, Washington, DC
    Image Owner: Callan Bentley



    Description:

    The foliation has been "kinked" here.



  38. Scale

    Snapshot Title: Scale
    Taken by: Callan Bentley

    Image: Klingle Valley metaconglomerate, Laurel Formation, Rock Creek Shear Zone, Washington, DC
    Image Owner: Callan Bentley



    Description:

    This pencil serves as a sense of scale. It's in a hollow, so it's mostly blurry, though thankfully that implies the rock around it should be in focus... Black bars along the side each measure 1 cm.



  39. Clast

    Snapshot Title: Clast
    Taken by: Callan Bentley

    Image: Klingle Valley metaconglomerate, Laurel Formation, Rock Creek Shear Zone, Washington, DC
    Image Owner: Callan Bentley



    Description:

    With well-defined edges.



  40. Clast with internal layering

    Snapshot Title: Clast with internal layering
    Taken by: Callan Bentley

    Image: Klingle Valley metaconglomerate, Laurel Formation, Rock Creek Shear Zone, Washington, DC
    Image Owner: Callan Bentley



    Description:

    Pre-existing metamorphic foliation? Sedimentary bedding? Volcanic flow banding?



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