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Callan Bentley's Snapshots

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  1. 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.



  2. 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?



  3. 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!



  4. 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.



  5. 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.



  6. 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.



  7. 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



  8. 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



  9. 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



  10. 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.



  11. 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.



  12. 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.



  13. 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.



  14. 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?



  15. Prius

    Snapshot Title: Prius
    Taken by: Callan Bentley

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



    Description:

    dorsal fin



  16. Offset

    Snapshot Title: Offset
    Taken by: Callan Bentley

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



    Description:

    Whose fault is this offset?



  17. 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?



  18. 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.



  19. 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



  20. Scale

    Snapshot Title: Scale
    Taken by: Callan Bentley

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



    Description:

    This is an inch.



  21. 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.



  22. 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



  23. 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



  24. 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?



  25. Scale

    Snapshot Title: Scale
    Taken by: Callan Bentley

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



    Description:

    This is a centimeter.



  26. Scale

    Snapshot Title: Scale
    Taken by: Callan Bentley

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



    Description:

    This is an inch.



  27. 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.



  28. ...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?



  29. 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.



  30. 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.



  31. 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.



  32. Kinky crenulations

    Snapshot Title: Kinky crenulations
    Taken by: Callan Bentley

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



    Description:

    Closely-spaced folds



  33. Crenulation folds

    Snapshot Title: Crenulation folds
    Taken by: Callan Bentley

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



    Description:

    Kinky folds



  34. Bedding vs. cleavage

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

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



    Description:

    Bedding is subhorizontal here, curving over to moderately-dipping (to the left / west) at far left. Cleavage is uniformly to the opposite direction (east) at a moderate to steep angle.



  35. Scale

    Snapshot Title: Scale
    Taken by: Callan Bentley

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



    Description:

    Pencil for scale. Black rectangles along the side of the pencil are each one centimeter long.



  36. Hackles

    Snapshot Title: Hackles
    Taken by: Callan Bentley

    Image: Weverton Formation atop Biscuit Mountain (Outdoor Lab)
    Image Owner: Callan Bentley



    Description:

    A small array of hackles decorates the face of the outcrop here. These "ruffle" like features form at the edge of fractures as they open up.



  37. Big, bold scour

    Snapshot Title: Big, bold scour
    Taken by: Callan Bentley

    Image: Weverton Formation atop Biscuit Mountain (Outdoor Lab)
    Image Owner: Callan Bentley



    Description:

    Note the asymmetry (possibly due to top-to-the-left shearing) and the lack of internal cross-bedding.



  38. Skulking scour

    Snapshot Title: Skulking scour
    Taken by: Callan Bentley

    Image: Weverton Formation atop Biscuit Mountain (Outdoor Lab)
    Image Owner: Callan Bentley



    Description:

    Small scour with 1 or 2 internal cross-beds, hiding in the shadows....



  39. Bedding vs. cleavage

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

    Image: Weverton Formation atop Biscuit Mountain (Outdoor Lab)
    Image Owner: Callan Bentley



    Description:

    Bedding is shallowly dipping to the right (east), while cleavage is moderately dipping to the right (east). This relationship suggests the bedding is right-side-up (i.e., it has not been bodily flippe...



  40. Laminations

    Snapshot Title: Laminations
    Taken by: Callan Bentley

    Image: Weverton Formation atop Biscuit Mountain (Outdoor Lab)
    Image Owner: Callan Bentley



    Description:

    Fine-scale layering is apparent in this outcrop.



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