1. Skip to navigation
  2. Skip to content
  3. Skip to sidebar


Callan Bentley's Snapshots

Go to page:
  1. 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))



  2. 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.



  3. 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.



  4. 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).



  5. 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!



  6. 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.



  7. 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



  8. 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.



  9. 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.



  10. 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.



  11. 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.



  12. 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



  13. 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



  14. Kink
  15. 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.



  16. 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.



  17. 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.



  18. 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.



  19. 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.



  20. 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.



  21. 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.



  22. 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.



  23. 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?



  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:

    Felsite? Quartzite?



  25. 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:

    Looks like a dark mica-rich schist cobble?



  26. Pseudomorph

    Snapshot Title: Pseudomorph
    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)



  27. 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 has one-centimeter black bars along its side.



  28. Stretched clast

    Snapshot Title: 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:

    Maybe with a second clast fused into it at lower left?



  29. Stretched clast

    Snapshot Title: 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:

    What is the axial ratio of this clast, as expressed on this surface?



  30. 1 inch

    Snapshot Title: 1 inch
    Taken by: Callan Bentley

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



    Description:

    On a scale card provided by the Virginia DGMR.



  31. Scale pencil

    Snapshot Title: Scale pencil
    Taken by: Callan Bentley

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



    Description:

    Slightly blurry, due to its location in a hollow, but the rock is in focus! 1 cm demarcations on the side of the pencil.



  32. Kinked foliation

    Snapshot Title: Kinked 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:

    Right at the fracture. Right at the transition between brown and gray.



  33. Stretched mafic clasts

    Snapshot Title: Stretched mafic clasts
    Taken by: Callan Bentley

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



    Description:

    Not as obvious to the eye as the milky quartz stretched clasts / boudins, but these dark colored clasts are present, too.



  34. Big clasts

    Snapshot Title: Big clasts
    Taken by: Callan Bentley

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



    Description:

    Or boudins?



  35. Pop

    Snapshot Title: Pop
    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 bubble caught in the moment of popping!



  36. 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:

    These highly foliated rocks are part of the Rock Creek Shear Zone, a ductile "fault" running north-south through NW DC.



  37. Kensington Tonalite boulder

    Snapshot Title: Kensington Tonalite boulder
    Taken by: Callan Bentley

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



    Description:

    Derived from outcrops upstream at the contact between the Kensington Tonalite and Laurel Formation.



  38. Kink within a kink

    Snapshot Title: Kink within a 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:

    Back out a bit for the larger kink's context.



  39. Big kink band

    Snapshot Title: Big 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:

    bounded by fractures



  40. Fold hinge

    Snapshot Title: 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:

    Almost indiscernible



Go to page: