On top of one of the peaks in the Uinta mountain range I found this plastic thing with small black flat glass marbles in it. It was several feet long and there were small holes underneath of the flat marbles.

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The plastic holder had holes below and it had a temperature reader attached.

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What exactly is this thing for?

  • After reading the question again, do the drains go all the way to the bottom of the troughs? It's not visible from the image. Could some water remain or would it drain completely?
    – Gabriel
    Commented Apr 30, 2019 at 19:20
  • @GabrielC I added a closeup Commented Apr 30, 2019 at 23:34
  • Was this apparatus in a low area or depression on the mountain? Did the area appear to be capable of flooding or holding water? Was it near a lake? It could be a coincidence/accident that the thermometer was next to the tray.
    – B540Glenn
    Commented May 1, 2019 at 17:05
  • @B540Glenn It was ontop of the peak which was pretty flat. Didn't look like it would flood Commented May 1, 2019 at 17:09
  • I can't understand how it remained undisturbed. I would have thought animals and hikers would have fiddled enough with it to have dispersed or removed a fair number of the pellets.
    – ab2
    Commented May 1, 2019 at 18:30

1 Answer 1


Without having more info on the specific parameters of the study, it's hard to know exactly what they were looking for.

Either water or snowpack characterization might be very likely subjects. I'm wondering if they used black pebbles specifically because they are black, which would suggest their ability to gain heat is important. Or maybe it's not relevant at all and only their smooth polished surface was important (which would make sense since high gloss reflects a little more than if it was matte).

The Onset HOBO unit is self contained and might be intended to be used where it's located, as an air temp sensor, or it was attached so it doesn't get lost until readings need to be done in the pebbly troughs. The battery life on those things is 6 years, so it might be recording data continuously even when unattended. Air temperatures might be relevant if the study is on air pollutants (traces of which could be detected in rainfall or snowpack).

If the study is about analyzing particulates, the pebbles in the troughs might be used to shelter the water from being blown away by the wind or to slow down the evaporation process from sunlight. The pebbles would also prevent sediments from getting mixed again and escaping through the drains at the top.

In any case, if someone more expert in the specific methodology used here can describe precisely what the goal of this study was, I'll be as interested as you are. I have a couple hunches, but it might be related to ozone pollution.

  • Flat marbles is probably a better description than pebbles Commented Apr 30, 2019 at 19:15
  • @CharlieBrumbaugh Maybe this whole setup is just a QC step in the glass marble company's manufacturing process. /s
    – Gabriel
    Commented Apr 30, 2019 at 19:19

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