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Callan Bentley's Snapshots

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  1. 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?



  2. 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?



  3. 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)



  4. 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.



  5. 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?



  6. 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?



  7. 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.



  8. 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.



  9. 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.



  10. 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.



  11. 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?



  12. 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!



  13. 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.



  14. 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.



  15. 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.



  16. 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



  17. 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



  18. Small kink band

    Snapshot Title: Small 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:

    Overprinting foliation



  19. 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:

    Within metagraywacke matrix.



  20. Scale

    Snapshot Title: Scale
    Taken by: Callan Bentley

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



    Description:

    Scale card from the Virginia DGMR, with inches and centimeters demarcated along the top and bottom edges.



  21. 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:

    Black bars along the side are each one centimeter in length.



  22. Rust

    Snapshot Title: Rust
    Taken by: Callan Bentley

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



    Description:

    Diagenetic deposits of iron oxides highlight bedding.



  23. Cross-bedding

    Snapshot Title: Cross-bedding
    Taken by: Callan Bentley

    Image: Hanging Rock Anticline, east side
    Image Owner: Callan Bentley



    Description:

    Which way was the current flowing?



  24. Prius

    Snapshot Title: Prius
    Taken by: Callan Bentley

    Image: Hanging Rock Anticline, east side
    Image Owner: Callan Bentley



    Description:

    dorsal fin



  25. Offset

    Snapshot Title: Offset
    Taken by: Callan Bentley

    Image: Hanging Rock Anticline, east side
    Image Owner: Callan Bentley



    Description:

    Whose fault is this offset?



  26. Cross-beds

    Snapshot Title: Cross-beds
    Taken by: Callan Bentley

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



    Description:

    Which was was the current flowing when these sands were deposited?



  27. Scale

    Snapshot Title: Scale
    Taken by: Callan Bentley

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



    Description:

    Pencil w/ 1-cm demarcations along the side.



  28. Meso-scale fold

    Snapshot Title: Meso-scale fold
    Taken by: Callan Bentley

    Image: Folded strata of the Silurian Tonoloway Formation
    Image Owner: Callan Bentley



    Description:

    in strongly-laminated layer



  29. Scale

    Snapshot Title: Scale
    Taken by: Callan Bentley

    Image: Martinsburg Formation exposed at Staunton, Virginia
    Image Owner: Callan Bentley



    Description:

    This is an inch.



  30. Scale

    Snapshot Title: Scale
    Taken by: Callan Bentley

    Image: Martinsburg Formation exposed at Staunton, Virginia
    Image Owner: Callan Bentley



    Description:

    Pencil with centimeter-scale demarcations along the side.



  31. A closer look

    Snapshot Title: A closer look
    Taken by: Callan Bentley

    Image: Martinsburg Formation exposed at Staunton, Virginia
    Image Owner: Callan Bentley



    Description:

    If you want a close look at an outcrop just east of here, try this one:
    gigapan.com/gigapans/127961



  32. A closer look

    Snapshot Title: A closer look
    Taken by: Callan Bentley

    Image: Martinsburg Formation exposed at Staunton, Virginia
    Image Owner: Callan Bentley



    Description:

    Zoom in here with this GigaPan:
    gigapan.com/gigapans/127962



  33. Bedding vs. cleavage

    Snapshot Title: Bedding vs. cleavage
    Taken by: Callan Bentley

    Image: Martinsburg Formation exposed at Staunton, Virginia
    Image Owner: Callan Bentley



    Description:

    What is the angle between bedding and cleavage at this site?



  34. Scale

    Snapshot Title: Scale
    Taken by: Callan Bentley

    Image: Martinsburg Formation exposed at Staunton, Virginia
    Image Owner: Callan Bentley



    Description:

    This is a centimeter.



  35. Scale

    Snapshot Title: Scale
    Taken by: Callan Bentley

    Image: Martinsburg Formation exposed at Staunton, Virginia
    Image Owner: Callan Bentley



    Description:

    This is an inch.



  36. Bedding / cleavage relationships

    Snapshot Title: Bedding / cleavage relationships
    Taken by: Callan Bentley

    Image: Martinsburg Formation exposed at Staunton, Virginia
    Image Owner: Callan Bentley



    Description:

    Bedding is almost vertical; cleavage dips steeply to the east.



  37. ...You know, except for geologists...

    Snapshot Title: ...You know, except for geologists...
    Taken by: Callan Bentley

    Image: Martinsburg Formation exposed at Staunton, Virginia
    Image Owner: Callan Bentley



    Description:

    ...right?



  38. Three stripes of turbidite

    Snapshot Title: Three stripes of turbidite
    Taken by: Callan Bentley

    Image: Martinsburg Formation exposed at Staunton, Virginia
    Image Owner: Callan Bentley



    Description:

    This snapshot would make a great flag.



  39. How old was this tree when it died?

    Snapshot Title: How old was this tree when it died?
    Taken by: Callan Bentley

    Image: Harpers Formation exposed at Glasscock Gap, Virginia (Outdoor Lab)
    Image Owner: Callan Bentley



    Description:

    Regardless, thanks to Anthony (Outdoor Lab staff) for surgically extracting it from the GigaPan view with the Stihl chainsaw.



  40. Terrace gravel deposits

    Snapshot Title: Terrace gravel deposits
    Taken by: Callan Bentley

    Image: Harpers Formation exposed at Glasscock Gap, Virginia (Outdoor Lab)
    Image Owner: Callan Bentley



    Description:

    Implying erosion followed by deposition followed by erosion again.



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