Heavy rains in late July 2010 triggered the mass wasting that occurred in this mountain valley near Durango, Colorado. Heavy equipment is clearing away material that blocked railroad tracks and significantly narrowed the stream channel. What type of mass wasting likely occurred here?

Land Slides

Explanation:

The type of mass wasting that most likely would have occurred in the mountain valley near Durango, Colorado is land slide or land slump.

The heavy rain might have loosened the soil and the rock strata of the mountain valley. And this Loosened mud, rock would have slide down along the inclined slops of the mountain leading to land slides.