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