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Callan Bentley's Snapshots

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  1. Sense of scale II

    Snapshot Title: Sense of scale II
    Taken by: Callan Bentley

    Image: Pseudocraters at Lake Mývatn, Iceland
    Image Owner: Callan Bentley



    Description:

    Another person to provide a scale calibration.



  2. Sense of scale

    Snapshot Title: Sense of scale
    Taken by: Callan Bentley

    Image: Pseudocraters at Lake Mývatn, Iceland
    Image Owner: Callan Bentley



    Description:

    Inadvertent field assistants.



  3. Example label

    Snapshot Title: Example label
    Taken by: Callan Bentley

    Image: Red cross-beds (annotated)
    Image Owner: Callan Bentley



    Description:

    Showing sites where older cross-beds are truncated against the bottom of younger beds.



  4. Scale

    Snapshot Title: Scale
    Taken by: Callan Bentley

    Image: Red cross-beds (annotated)
    Image Owner: Callan Bentley



    Description:

    Black bar is 1 cm in width



  5. Sense of scale

    Snapshot Title: Sense of scale
    Taken by: Callan Bentley

    Image: Komatiitic ash (meteorite impact layer), Barberton Greenstone Belt, South Africa
    Image Owner: Callan Bentley



    Description:

    This black bar is 1 cm wide.



  6. Longitudinal fractures

    Snapshot Title: Longitudinal fractures
    Taken by: Callan Bentley

    Image: Spinifex texture in komatiite, Barberton Greenstone Belt, South Africa
    Image Owner: Callan Bentley



    Description:

    Cutting across the crystals orthogonal to their long axis (shortest distance required to break them).



  7. Spinifex

    Snapshot Title: Spinifex
    Taken by: Callan Bentley

    Image: Spinifex texture in komatiite, Barberton Greenstone Belt, South Africa
    Image Owner: Callan Bentley



    Description:

    Nice diverging "V" shape seen here.



  8. Relatively fresh surface

    Snapshot Title: Relatively fresh surface
    Taken by: Callan Bentley

    Image: Spinifex texture in komatiite, Barberton Greenstone Belt, South Africa
    Image Owner: Callan Bentley



    Description:

    To contrast with the rest of the sample.



  9. One cm

    Snapshot Title: One cm
    Taken by: Callan Bentley

    Image: Spinifex texture in komatiite, Barberton Greenstone Belt, South Africa
    Image Owner: Callan Bentley



    Description:

    Tall



  10. Sense of scale

    Snapshot Title: Sense of scale
    Taken by: Callan Bentley

    Image: Differential Weathering, Sideling Hill, Maryland
    Image Owner: Marissa Dudek



    Description:

    Field notebook for scale.



  11. Double trouble

    Snapshot Title: Double trouble
    Taken by: Callan Bentley

    Image: Spechty Kopf Diamictite, Sideling Hill, Maryland
    Image Owner: Marissa Dudek



    Description:

    Two outsized clasts in close proximity.



  12. Sense of scale

    Snapshot Title: Sense of scale
    Taken by: Callan Bentley

    Image: Spechty Kopf Diamictite, Sideling Hill, Maryland
    Image Owner: Marissa Dudek



    Description:

    Mechanical pencil w/ 1-cm markings



  13. Outsized clast

    Snapshot Title: Outsized clast
    Taken by: Callan Bentley

    Image: Spechty Kopf Diamictite, Sideling Hill, Maryland
    Image Owner: Marissa Dudek



    Description:

    Big chunk 'floating' in the clay-rich matrix.



  14. Outsized clast

    Snapshot Title: Outsized clast
    Taken by: Callan Bentley

    Image: Spechty Kopf Diamictite, Sideling Hill, Maryland
    Image Owner: Marissa Dudek



    Description:

    Big chunk in the clay-rich matrix



  15. Eutaxitic lens

    Snapshot Title: Eutaxitic lens
    Taken by: Callan Bentley

    Image: Huckleberry Ridge Tuff, Madison Valley, Montana
    Image Owner: Callan Bentley



    Description:

    Squashed blob of frothy pumice.



  16. Compaction

    Snapshot Title: Compaction
    Taken by: Callan Bentley

    Image: Huckleberry Ridge Tuff, Madison Valley, Montana
    Image Owner: Callan Bentley



    Description:

    Eutaxitic lens wrapping around the top of a stiff phenocryst.



  17. Scale

    Snapshot Title: Scale
    Taken by: Callan Bentley

    Image: Huckleberry Ridge Tuff, Madison Valley, Montana
    Image Owner: Callan Bentley



    Description:

    This is 1 cm tall.



  18. Sense of scale

    Snapshot Title: Sense of scale
    Taken by: Callan Bentley

    Image: Portrush: hornfels (contact metamorphosed Lias shale) above Portrush gabbroic/doleritic sill
    Image Owner: Callan Bentley



    Description:

    Black bars on the side of this pencil are each 1 cm long.



  19. Sense of scale

    Snapshot Title: Sense of scale
    Taken by: Callan Bentley

    Image: Portrush: hornfels (contact metamorphosed Lias shale) above Portrush gabbroic/doleritic sill
    Image Owner: Callan Bentley



    Description:

    Mechanical pencil w/ 1-cm black bars along its side.



  20. Sense of scale

    Snapshot Title: Sense of scale
    Taken by: Callan Bentley

    Image: Portrush: hornfels (contact metamorphosed Lias shale) above Portrush gabbroic/doleritic sill
    Image Owner: Callan Bentley



    Description:

    Pencil w/ 1 cm black bars along its side.



  21. Crack

    Snapshot Title: Crack
    Taken by: Callan Bentley

    Image: Dropstones in weakly-lithified "silt-ite" from Looking Glass Highway, east of Glacier National Park
    Image Owner: Callan Bentley



    Description:

    indication of the weak state of lithification in this sample.



  22. Empty socket

    Snapshot Title: Empty socket
    Taken by: Callan Bentley

    Image: Dropstones in weakly-lithified "silt-ite" from Looking Glass Highway, east of Glacier National Park
    Image Owner: Callan Bentley



    Description:

    where a pebble popped out.



  23. Quartzite pebble

    Snapshot Title: Quartzite pebble
    Taken by: Callan Bentley

    Image: Dropstones in weakly-lithified "silt-ite" from Looking Glass Highway, east of Glacier National Park
    Image Owner: Callan Bentley



    Description:

    with pyrolusite dendrites on one side.



  24. Pyrolusite
  25. Appekuny Formation

    Snapshot Title: Appekuny Formation
    Taken by: Callan Bentley

    Image: Dropstones in weakly-lithified "silt-ite" from Looking Glass Highway, east of Glacier National Park
    Image Owner: Callan Bentley



    Description:

    Green argillite



  26. Grinnell Formation

    Snapshot Title: Grinnell Formation
    Taken by: Callan Bentley

    Image: Dropstones in weakly-lithified "silt-ite" from Looking Glass Highway, east of Glacier National Park
    Image Owner: Callan Bentley



    Description:

    Red argillite



  27. Grinnell Formation

    Snapshot Title: Grinnell Formation
    Taken by: Callan Bentley

    Image: Dropstones in weakly-lithified "silt-ite" from Looking Glass Highway, east of Glacier National Park
    Image Owner: Callan Bentley



    Description:

    Reddish quartzite



  28. Scale

    Snapshot Title: Scale
    Taken by: Callan Bentley

    Image: Dropstones in weakly-lithified "silt-ite" from Looking Glass Highway, east of Glacier National Park
    Image Owner: Callan Bentley



    Description:

    This black bar is 1 cm wide



  29. Scale

    Snapshot Title: Scale
    Taken by: Callan Bentley

    Image: Portrush sill: gabbro/diabase
    Image Owner: Callan Bentley



    Description:

    This is 1 cm wide.



  30. Really rounded pebbles

    Snapshot Title: Really rounded pebbles
    Taken by: Callan Bentley

    Image: Felsic intrusion with xenoliths
    Image Owner: Callan Bentley



    Description:

    This spot is high above the beach. How did these pebbles get so well rounded?



  31. Differential weathering

    Snapshot Title: Differential weathering
    Taken by: Callan Bentley

    Image: Felsic intrusion with xenoliths
    Image Owner: Callan Bentley



    Description:

    The felsic stuff (~granite) stands up to the wind's abrasion better than the more mafic constituents, making the granite weather out in positive relief.



  32. Xenolith variation

    Snapshot Title: Xenolith variation
    Taken by: Callan Bentley

    Image: Felsic intrusion with xenoliths
    Image Owner: Callan Bentley



    Description:

    Freshly stoped vs. mostly assimilated?



  33. Sense of scale

    Snapshot Title: Sense of scale
    Taken by: Callan Bentley

    Image: Felsic intrusion with xenoliths
    Image Owner: Callan Bentley



    Description:

    This is a lens cap for a 35 mm camera



  34. Blotchy

    Snapshot Title: Blotchy
    Taken by: Callan Bentley

    Image: A second view of the felsite intrusion
    Image Owner: Callan Bentley



    Description:

    There was a lot of this texture in the area, too - I interpret it as magma immiscibility resulting in the "Dalmatian" polka-dotting, then highlighted by differential weathering of the two compositions...



  35. Anatexis?

    Snapshot Title: Anatexis?
    Taken by: Callan Bentley

    Image: A second view of the felsite intrusion
    Image Owner: Callan Bentley



    Description:

    Interesting texture here - is this evidence of partial melting?



  36. Xenoliths

    Snapshot Title: Xenoliths
    Taken by: Callan Bentley

    Image: A second view of the felsite intrusion
    Image Owner: Callan Bentley



    Description:

    Nice array of mafic fragments/shards caught up in the granitic (felsic) dike.



  37. Relative dating

    Snapshot Title: Relative dating
    Taken by: Callan Bentley

    Image: A second view of the felsite intrusion
    Image Owner: Callan Bentley



    Description:

    Which of the two rock units is older, the light-colored one or the dark-colored one?



  38. Lens cap

    Snapshot Title: Lens cap
    Taken by: Callan Bentley

    Image: A second view of the felsite intrusion
    Image Owner: Callan Bentley



    Description:

    To provide a sense of scale



  39. Sediment

    Snapshot Title: Sediment
    Taken by: Callan Bentley

    Image: Felsite intrusion, Iceland
    Image Owner: Callan Bentley



    Description:

    What can you say about the sediment at this site?



  40. Inclusions

    Snapshot Title: Inclusions
    Taken by: Callan Bentley

    Image: Felsite intrusion, Iceland
    Image Owner: Callan Bentley



    Description:

    Shards of mafic rock (xenoliths) would allow relative dating on the principle of inclusions - the broken pieces must be of the older rock, and the felsic rock that surrounds them must be younger.



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