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Callan Bentley's Snapshots

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  1. 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.



  2. 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.



  3. 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



  4. 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



  5. 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.



  6. 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



  7. 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.



  8. 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.



  9. 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!)



  10. 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.



  11. 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.



  12. 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



  13. 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



  14. 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.



  15. 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.



  16. 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.



  17. Clast

    Snapshot Title: Clast
    Taken by: Callan Bentley

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



    Description:

    of milky quartz



  18. Felsic clast

    Snapshot Title: Felsic clast
    Taken by: Callan Bentley

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



    Description:

    Must be older than the Sykesville Formation that includes it.



  19. Big tabular clast

    Snapshot Title: Big tabular clast
    Taken by: Callan Bentley

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



    Description:

    A big slabby chunk of quartzite included in the metagraywacke/schist matrix.



  20. 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 is the butt end of the hammer.



  21. Reaction rim

    Snapshot Title: Reaction rim
    Taken by: Callan Bentley

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



    Description:

    Another signal of chemical re-equilibration between clast and matrix.



  22. Mafic clast w/ reaction rim

    Snapshot Title: Mafic clast w/ reaction rim
    Taken by: Callan Bentley

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



    Description:

    Amphibolite?



  23. Milky quartz inclusions

    Snapshot Title: Milky quartz inclusions
    Taken by: Callan Bentley

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



    Description:

    exposed on the plane of foliation.



  24. Hammer for scale

    Snapshot Title: Hammer for scale
    Taken by: Callan Bentley

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



    Description:

    Top of the handle



  25. Students

    Snapshot Title: Students
    Taken by: Callan Bentley

    Image: Gastropod duplex w/ people for scale
    Image Owner: Callan Bentley



    Description:

    Zack, Matt, and Jake, checking out the structural geology.



  26. Percussion marks

    Snapshot Title: Percussion marks
    Taken by: Callan Bentley

    Image: Second Generation Quartz, Billy Goat Trail
    Image Owner: Marissa Dudek



    Description:

    Great examples.



  27. Percussion marks

    Snapshot Title: Percussion marks
    Taken by: Callan Bentley

    Image: Second Generation Quartz, Billy Goat Trail
    Image Owner: Marissa Dudek



    Description:

    Bouncing cobbles in the ancient Potomac River slammed into this postively-weathering vein to make these features.



  28. A closer look

    Snapshot Title: A closer look
    Taken by: Callan Bentley

    Image: Faulted- Tonoloway
    Image Owner: Alan Pitts



    Description:

    Details here:
    gigapan.com/gigapans/174628



  29. Slogan

    Snapshot Title: Slogan
    Taken by: Callan Bentley

    Image: Syncline Fold, Corridor H
    Image Owner: Marissa Dudek



    Description:

    Resolution's good enough to read off the fine print on the license plate.



  30. Fault

    Snapshot Title: Fault
    Taken by: Callan Bentley

    Image: Syncline Fold, Corridor H
    Image Owner: Marissa Dudek



    Description:

    A big difference in bedding orientation in upper left of snapshot relative to lower right, and an oxidized zone of rubble in between. Fault!



  31. Beautiful brach

    Snapshot Title: Beautiful brach
    Taken by: Callan Bentley

    Image: Fossils in Reynolds Limestone, Mauch Chunk Formation
    Image Owner: Marissa Dudek



    Description:

    Exterior



  32. Eye

    Snapshot Title: Eye
    Taken by: Callan Bentley

    Image: Helderberg Limestone, Corridor H, West Virginia
    Image Owner: Callan Bentley



    Description:

    This one has an iris!



  33. Hmmm

    Snapshot Title: Hmmm
    Taken by: Callan Bentley

    Image: Helderberg Limestone, Corridor H, West Virginia
    Image Owner: Callan Bentley



    Description:

    What's up with these half-spherical concavities?



  34. Microcave

    Snapshot Title: Microcave
    Taken by: Callan Bentley

    Image: Helderberg Limestone, Corridor H, West Virginia
    Image Owner: Callan Bentley



    Description:

    Looks like a good site for a bird nest?



  35. Differential dissolution

    Snapshot Title: Differential dissolution
    Taken by: Callan Bentley

    Image: Helderberg Limestone, Corridor H, West Virginia
    Image Owner: Callan Bentley



    Description:

    Some of these strata are more soluble than others.



  36. Clover

    Snapshot Title: Clover
    Taken by: Callan Bentley

    Image: Helderberg Limestone, Corridor H, West Virginia
    Image Owner: Callan Bentley



    Description:

    in bloom



  37. Flowers

    Snapshot Title: Flowers
    Taken by: Callan Bentley

    Image: Helderberg Limestone, Corridor H, West Virginia
    Image Owner: Callan Bentley



    Description:

    A small bouquet



  38. Extensional veins

    Snapshot Title: Extensional veins
    Taken by: Callan Bentley

    Image: Helderberg Limestone, Corridor H, West Virginia
    Image Owner: Callan Bentley



    Description:

    Filled w/ pure white calcite



  39. Intersecting joint sets

    Snapshot Title: Intersecting joint sets
    Taken by: Callan Bentley

    Image: Helderberg Limestone, Corridor H, West Virginia
    Image Owner: Callan Bentley



    Description:

    A conjugate set?



  40. Dissolution

    Snapshot Title: Dissolution
    Taken by: Callan Bentley

    Image: Helderberg Limestone, Corridor H, West Virginia
    Image Owner: Callan Bentley



    Description:

    on joint surfaces. Also, oxidation.



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