Slumgullion Pass & Slumgullion Earthflow

The Slumgullion Earthflow and Slumgullion Pass (11,361') are located on Highway 149, the Silver Thread Scenic Byway, between Creede and Lake City. The Pass is not really a pass but is actually a low point on a ridge where it is possible to drop down to the Lake Fork of the Gunnison River.

The earthflow, or mudslide, began some 700 years ago when, lubricated by heavy rains, the weak volcanic tuff and breccia on the southern flank of Mesa Seco slumped several miles down the steep mountainside. The photo to the left shows some of it. About 350 years ago, a second earthflow started from the top of the mountain. The new flow is still moving, sometimes as much as twenty feet in a year.

The first flow was so large and cataclysmic, it blocked the Lake Fork of the Gunnison River and created Lake San Cristobal, Colorado's second largest natural lake.