That is the fancy name given to this massive landslide which occurred over 850 years ago. A large portion of the top of Mesa Seco, weakened by rain, finally gave way and 4,000 tons of dirt slide down the hill. This dammed up a river and created Lake Cristobal, the second largest natural lake in Colorado.
A second slide occurred approximately 350 years ago. That clump of dirt is still moving downhill at about 20 feet per year.
This is from the bottom of the hill looking up:
And looking 45 degrees to the left from where I took that picture I saw this more recent area, right next to the road:
I decided I’d better keep on moving down the road before the road started moving on it’s own…. Besides, I was anxious to get to my next stop (see next post).