The above photo shows the Madison Slide just outside the northwestern corner of Yellowstone National Park. The canyon at the right center of the photo is the route that the Madison River takes to the Madison Valley just beyond (upper right). The photo was taken just after the slide occurred, and before engineers cut a new channel for the river to drain into the valley downstream.

Question #3

What changes in the hillslope and river valley resulted from the slide?

What evidence can you see in the photo that tells you the slide moved with high velocity?

The above photo is of the Gros Ventre Slide in northwestern Wyoming, on the west side of Jackson Hole and in the valley of the Gros Ventre River. Note that the situation here is similar to that of the Madison Slide, where the slide mass blocked the course of the river, resulting in the formation of a lake behind the dam of debris. If you look carefully in the cliffs on the hill above the slide, in the left and slightly above the center of the photo, you can see the layers of sedimentary rock that make up the hillside. Note that these layers are tilted to the left, in the same direction in which the slide moved.

The above cross section shows the pre-slide surface for the Gros Ventre Slide, as well as the present position of the landslide debris. It also shows the tilted bedrock referred to in the caption for the above photo. Note that the directions of the cross section are reversed from the directions shown in the photograph.

Question #4

Compare the slope of the preslide surface with the tilt of the bedrock. Then, note that a permeable sandstone (meaning, a sandstone through which water can pass easily) overlies an impermeable shale (meaning that water will not pass through the shale). Now, describe the relationship between the slide mass and the boundary of the permeable and impermeable rock layers. Finally, discribe the factors that were most likely in causing this slide.

Above is a view of a mass wasting deposit in the mountains of Idaho.

Question #5

Is this the deposit the result of a slump, slide, or earth/debris flow? Give evidence, visible in the photo, that supports your answer.

Apologies for the poor quality of this photo. Mass wasting has occurred along the banks of this river in South Dakota.

Question #6

Was the mass wasting event one of creep, slump, slide, or flow? Give evidence from the photo for your answer.