David Cox III

  • 4 days, 17 hours ago
    David Cox III posted a new activity comment

    Barracuda?

  • 3 weeks, 4 days ago
    David Cox III posted a new activity comment

    or one on Mesozoic trees called “Jurassic Bark”

  • 1 month ago
  • 2 months ago
    David Cox III posted a new activity comment

    Mike, thanks for the great explanation. Very thorough. I look forward to hearing the results.

  • 2 months ago
    David Cox III posted a new activity comment

    Mike, could you give a bit of detail on what we are looking at in this photo? How is a paleomag sample collected and prepared? Just the very basics would be great. Thanks.

    • Of course! Montbrook paleomagnetism sediment samples were collected throughout the section to compare results from the top and bottom. All sample orientations were recorded in the field as well as on the sample themselves (that’s the black arrow you see on the pictured sediment). Since we all know how crumbly the sand-dominated Montbrook sediments can be, a heavy coat of lacquer was applied to harden the sample as well as ‘lock’ in the position of sediment grains. Back in the lab (in this case, my garage), a diamond tipped rock saw is used to cut the larger samples into smaller ~2.3cm cubes (standard size for the machinery used to conduct paleomagnetic analysis). Ideally, each larger sample will be worked into 4 of these smaller cubes. Cubed samples are wrapped in tin foil for rigidity/protection while they are being stored!
      -3 cubes are prepped to determine remanant paleomagnetic orientation, so it is essential that the direction of the black arrow from the larger sample translates over into these smaller samples. Why 3 samples? At least three samples are needed for analysis in order to be statistically significant. As with most things in science, the more repetitions/tested samples we can get, the better!
      – 1 other sample is prepped and designated for composition analysis in order to test what minerals within the Montbrook sediment lend themselves to magnetization (ex: hematite/magnetite).

      All in all, I have about 50 samples prepped. Paleomagnetism will not give us an exact age, but it is a great method to support the site’s estimated age which has been suggested strictly through vertebrate biochronology. With any luck, we may see a reversal in earth’s magnetic poles from the top of the geologic sequence from the bottom. If so (fingers crossed), this can be compared to well-documented magnetic records from the Late Miocene to further constrain the age of Montbrook!

      • Mike, thanks for the great explanation. Very thorough. I look forward to hearing the results.

  • 2 months, 1 week ago
    Max Jones and David Cox III are now friends
  • 2 months, 1 week ago
    Bruce MacFadden and David Cox III are now friends
  • 3 months ago
    David Cox III posted an update

    Good morning Bruce.

    Any chance of getting the Montbrook geology seminar notes / handouts posted for those of us out of town?

    Thanks.

    Dave Cox

     

  • 3 months, 1 week ago
    David Cox III posted a new activity comment

    Gives meaning to the old saying: “I’m so thirsty I could drink dust”.

  • 3 months, 1 week ago
  • 3 months, 1 week ago
    David Cox III posted an update in the group Nebraska Badlands

    Home in the Nebraska Badlands.  Fort Robinson is worth a visit if you are anywhere in the area.  A beautiful area with much western history and very relaxing. A wonderful place to enjoy the cool evening breeze on the porch.

  • 3 months, 1 week ago
    David Cox III posted an update in the group Nebraska Badlands


  • 3 months, 2 weeks ago
    David Cox III posted a new activity comment

    A small resoureful animal with a poor sense of smell?

    • Haha!!! Well, I’m not sure how smelly feces would be under water! Sadie was right, it was likely a crustacean that made the burrow.

  • 3 months, 3 weeks ago
    David Cox III posted an update

    View of the bluffs overlooking Fort Robinson.  A great place to stay when in the area.

  • 3 months, 3 weeks ago
    David Cox III posted an update in the group Nebraska Badlands


  • 3 months, 3 weeks ago
    David Cox III posted an update in the group Nebraska Badlands














  • 3 months, 3 weeks ago
    David Cox III posted a new activity comment

    You may be seeing some double posts soon. I uploaded 10 and uploaded 10 through flickr using urls. I’ll clean up what I can. Thanks and have a great day.

  • 3 months, 3 weeks ago
    David Cox III posted an update in the group Nebraska Badlands














  • 3 months, 3 weeks ago
    David Cox III posted an update in the group Nebraska Badlands














  • 3 months, 4 weeks ago
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