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Callan Bentley's Snapshots

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  1. Garnet

    Snapshot Title: Garnet
    Taken by: Callan Bentley

    Image: Garnet in Castner Marble, Franklin Mountains, West Texas
    Image Owner: Callan Bentley



    Description:

    porphyroblast - these rocks have been metamorphosed!



  2. Scale

    Snapshot Title: Scale
    Taken by: Callan Bentley

    Image: Garnet in Castner Marble, Franklin Mountains, West Texas
    Image Owner: Callan Bentley



    Description:

    This black bar on the side of the pencil is 1 cm long.



  3. A closer look

    Snapshot Title: A closer look
    Taken by: Callan Bentley

    Image: Castner Marble
    Image Owner: Callan Bentley



    Description:

    To see this rock face in more detail, check out this GigaPan:
    gigapan.com/gigapans/129286



  4. EPCC van

    Snapshot Title: EPCC van
    Taken by: Callan Bentley

    Image: Castner Marble
    Image Owner: Callan Bentley



    Description:

    El Paso Community College field trip vehicle



  5. Sign for scale

    Snapshot Title: Sign for scale
    Taken by: Callan Bentley

    Image: Castner Marble
    Image Owner: Callan Bentley



    Description:

    We forgot to put a sense of scale in this one.



  6. Refolded

    Snapshot Title: Refolded
    Taken by: Callan Bentley

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



    Description:

    The "jog" this antiform makes to the lower left suggests it has been refolded. Axial plane 1 is more or less vertical; Axial plane 2 dips moderately to the left.



  7. 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:

    growing on the surface of the rock.



  8. Contact

    Snapshot Title: Contact
    Taken by: Callan Bentley

    Image: Klingle Valley metaconglomerate, Laurel Formation, Rock Creek Shear Zone, Washington, DC
    Image Owner: Callan Bentley



    Description:

    of the granite intrusion.



  9. Sericite-after-staurolite porphyroblast

    Snapshot Title: Sericite-after-staurolite porphyroblast
    Taken by: Callan Bentley

    Image: Klingle Valley metaconglomerate, Laurel Formation, Rock Creek Shear Zone, Washington, DC
    Image Owner: Callan Bentley



    Description:

    Evidence of retrograde metamorphism.



  10. 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:

    Sheared out to oblate dimensions. Typical of deformation in the Rock Creek Shear Zone.



  11. Scale pencil

    Snapshot Title: Scale pencil
    Taken by: Callan Bentley

    Image: Klingle Valley metaconglomerate, Laurel Formation, Rock Creek Shear Zone, Washington, DC
    Image Owner: Callan Bentley



    Description:

    With 1 cm demarcations along the side.



  12. 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.



  13. 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).



  14. 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.



  15. 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.



  16. 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.



  17. Massive turbidite

    Snapshot Title: Massive turbidite
    Taken by: Callan Bentley

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



    Description:

    Dipping toward us!



  18. 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.



  19. 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.



  20. 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.



  21. 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.



  22. 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.



  23. 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.



  24. 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.



  25. 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.



  26. 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.



  27. 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.



  28. 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).



  29. 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).



  30. 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).



  31. 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).



  32. 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)



  33. 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)



  34. 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.



  35. 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.



  36. 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.



  37. 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.



  38. 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.



  39. 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.



  40. 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.



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