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Callan Bentley's Snapshots

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  1. Plumose

    Snapshot Title: Plumose
    Taken by: Callan Bentley

    Image: Brallier Formation near Deerfield, Virginia
    Image Owner: Callan Bentley



    Description:

    A nice example of plumose structure, showing the origin and growth of the joint face.



  2. Scours

    Snapshot Title: Scours
    Taken by: Callan Bentley

    Image: Brallier Formation near Deerfield, Virginia
    Image Owner: Callan Bentley



    Description:

    These (orange) sandstones were deposited by currents that apparently scoured into the underlying (older, pre-existing) mud layers (future shales).



  3. Shale laminations

    Snapshot Title: Shale laminations
    Taken by: Callan Bentley

    Image: Brallier Formation near Deerfield, Virginia
    Image Owner: Callan Bentley



    Description:

    Most of the Brallier is shale, not sandstone.



  4. Top of the bed

    Snapshot Title: Top of the bed
    Taken by: Callan Bentley

    Image: Brallier Formation near Deerfield, Virginia
    Image Owner: Callan Bentley



    Description:

    Bedding here dips toward the road and the observer.



  5. Sawteeth

    Snapshot Title: Sawteeth
    Taken by: Callan Bentley

    Image: Brallier Formation near Deerfield, Virginia
    Image Owner: Callan Bentley



    Description:

    The intersection of two joint sets divides the sandstone layers into diamond-shaped blocks that determine the weathering pattern along the edge of each bed.



  6. Massive turbidite

    Snapshot Title: Massive turbidite
    Taken by: Callan Bentley

    Image: Brallier Formation near Deerfield, Virginia
    Image Owner: Callan Bentley



    Description:

    Dipping toward us!



  7. Massive turbidite

    Snapshot Title: Massive turbidite
    Taken by: Callan Bentley

    Image: Brallier Formation near Deerfield, Virginia
    Image Owner: Callan Bentley



    Description:

    Dipping away from us.



  8. Calcite vein

    Snapshot Title: Calcite vein
    Taken by: Callan Bentley

    Image: Contact between New Market Formation (lower) and Lincolnshire Formation (upper), Staunton, Virginia
    Image Owner: Callan Bentley



    Description:

    Big rip, filled in with terrestrial juices chock full of dissolved calcium and carbonate.



  9. Synform

    Snapshot Title: Synform
    Taken by: Callan Bentley

    Image: Contact between New Market Formation (lower) and Lincolnshire Formation (upper), Staunton, Virginia
    Image Owner: Callan Bentley



    Description:

    The contact between the two formations bulges downward here due to Alleghanian folding.



  10. Antiform

    Snapshot Title: Antiform
    Taken by: Callan Bentley

    Image: Contact between New Market Formation (lower) and Lincolnshire Formation (upper), Staunton, Virginia
    Image Owner: Callan Bentley



    Description:

    The contact bulges upward here due to folding during the Alleghanian Orogeny.



  11. Bryozoans

    Snapshot Title: Bryozoans
    Taken by: Callan Bentley

    Image: Contact between New Market Formation (lower) and Lincolnshire Formation (upper), Staunton, Virginia
    Image Owner: Callan Bentley



    Description:

    These round things are cross-sections through branching-form bryozoans.



  12. Lincolnshire Fm

    Snapshot Title: Lincolnshire Fm
    Taken by: Callan Bentley

    Image: Contact between New Market Formation (lower) and Lincolnshire Formation (upper), Staunton, Virginia
    Image Owner: Callan Bentley



    Description:

    Darker, more thinly-bedded, and (here) intensely fossiliferous limestone.



  13. New Market Fm

    Snapshot Title: New Market Fm
    Taken by: Callan Bentley

    Image: Contact between New Market Formation (lower) and Lincolnshire Formation (upper), Staunton, Virginia
    Image Owner: Callan Bentley



    Description:

    Massive light-colored limestone with fenestral texture.



  14. Lil' folds

    Snapshot Title: Lil' folds
    Taken by: Callan Bentley

    Image: Contact between New Market Formation (lower) and Lincolnshire Formation (upper), Staunton, Virginia
    Image Owner: Callan Bentley



    Description:

    That have the same geometry as the main folds in the outcrop. Neat-o: the deformation here is scale-independent.



  15. 1 inch

    Snapshot Title: 1 inch
    Taken by: Callan Bentley

    Image: Contact between New Market Formation (lower) and Lincolnshire Formation (upper), Staunton, Virginia
    Image Owner: Callan Bentley



    Description:

    A scale card courtesy of the Virginia Department of Geology and Mineral Resources.



  16. Scale

    Snapshot Title: Scale
    Taken by: Callan Bentley

    Image: Contact between New Market Formation (lower) and Lincolnshire Formation (upper), Staunton, Virginia
    Image Owner: Callan Bentley



    Description:

    This pencil serves as a sense of scale, with black bars along the side each measuring 1 cm in length.



  17. 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:

    The orientation of the foliation here is 184°, 68° (expressed in right-hand rule).



  18. Outcrop orientation

    Snapshot Title: Outcrop orientation
    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 outcrop face's orientation is about 018°, 55° (right hand rule).



  19. 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).



  20. 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).



  21. 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)



  22. 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)



  23. 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.



  24. 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.



  25. 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.



  26. 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.



  27. 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.



  28. 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.



  29. 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.



  30. 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.



  31. 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.



  32. 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?



  33. 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.)



  34. 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.



  35. 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.



  36. 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))



  37. 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.



  38. 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.



  39. 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).



  40. 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!



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