2
$\begingroup$

While hiking Hyndman Peak in Idaho a couple weeks ago we noticed a rock slide that appeared to be formed by a glacier, however it was on the west side of the mountain. It was also strange that the downhill face was fairly sharp and was dirt/gravel instead of large rock. I only have a few smokey photos, and the satellite image is pretty poor, but just curious if anyone had any ideas.

Location in google maps

enter image description here

enter image description here

enter image description here

enter image description here

enter image description here

$\endgroup$
3
$\begingroup$

It is a normal rock slide, AKA a landslide, they happen all the time.

enter image description here

If a slope is not stable the rock collapses, landslides are very common and can be triggered by almost anything from rain, to imperceptible quakes, to simple erosion.

It could be rotational or translational the two blur together anyway. Most likely just a shallow rotational landslide.

The lower areas of a mountain being made of debris is extremely common, it is called a Scree slope. Where do you think all the rock that is eroded off the upper portions go?

| improve this answer | |
$\endgroup$
  • $\begingroup$ Cool, thanks! The part that set this formation apart from all the other rock debris in the area is that relatively sharp front on this one; as opposed to one that is level with the surface. There would have to be some interesting conditions to make that happen. I suppose it must have had a large amount snow in the level area in front of it that prevented the top surface from spilling over, giving that sharp edge. $\endgroup$ – ericnutsch Sep 30 at 18:00
  • $\begingroup$ A sharp edge is pretty normal as long as they are fresh, it may have even occurred after the snowfall. of course the edge creates a shadow that lets the snow hang a round a little longer . $\endgroup$ – John Sep 30 at 18:37
0
$\begingroup$

Some kind of "rock glacier" or moraine? enter image description here

source

| improve this answer | |
$\endgroup$
  • $\begingroup$ Thanks for the info! Could you expand on your thoughts or contrast against John's rockslide answer. Any way a glacier would create this sharp dirt front on the formation? Thanks! $\endgroup$ – ericnutsch Sep 30 at 18:03
  • 1
    $\begingroup$ I asked Prof. Dave Petley on his Landslide Blog. He replied: "I'm wondering if this is more of a rock glacier than a normal rockslide. I am no expert on these, but they often have this steep scarp on the downslope side. This is an example: blogs.egu.eu/geolog/2016/07/25/imaggeo-on-mondays-rock-glaciers" However, in that example there appears to be a stream running across the bottom imaggeo.egu.eu/view/4084 . $\endgroup$ – Keith McClary Oct 5 at 20:49
  • $\begingroup$ @ericnutsch I forgot to ping you in the previous comment. $\endgroup$ – Keith McClary Oct 7 at 19:42
  • $\begingroup$ Yeah I saw it but didn't have time to respond. Thanks for looking deeper into it. So if I visited the location again, say next year, is there any photos I could take or testing I can do to determine one way or the other? Rock glacier vs rock slide? $\endgroup$ – ericnutsch Oct 8 at 0:08
  • $\begingroup$ It could be a complex combination of processes: unifr.ch/geoscience/geographie/ssgmfiches/pergelisol/3401.php "Fig. 4 - Sorting of materials and steep front of the active rock glacier" $\endgroup$ – Keith McClary Oct 8 at 17:23

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.