Conor Watkins And J. David Rogers
Colorado Plateau Research
Vermilion Cliffs, AZ Landsliding
Introduction


Large slump blocks mantle the Vermilion Cliffs, especially along their western portions.


INTRODUCTION


The Vermilion Cliffs of northern Arizona are a 30-mile escarpment separating the Marble Platform from the Paria Plateau.  The escarpment is mantled by landslides and stretched from Lee's Ferry to House Rock.  Landslides include slump blocks, earthflows, and composite landslides that exhibit a combination of both types of movement.


Large slump blocks mantle the Vermilion Cliffs.  Notice the greenery of pinon pines atop the Paria Plateau.


Large slump blocks viewed near House Rock


A composite slump-earthflow slide is present in the midsection of the Vermilion Cliffs.



Sliding along the Vermilion Cliffs is mostly confined to the Petrified Forest member of the Chinle Formation, a highly plastic, montmorillonite-rich shale that erodes to form badlands topography.


This aerial photo of sliding along the Vermilion Cliffs shows multiple contacts where slide debris overlies the Petrified Forest Member of the Chinle Formation.


Diagram (from Baars, 1995) showing formations present along the Vermilion Cliffs.  The Marble Platform is floored in the Kaibab Limestone at its lowest level while the Paria Plateau is capped by the Navajo Sandstone.


Exposure of the entire stratigraphics column of the Vermilion Cliffs near the mouth of the Paria River, by Lee’s Ferry.


Several episodes of sliding and rapid cliff retreat along the escarpment appear to have occurred during the Quaternary, as multiple sequences of sliding are present.  Each sequence of sliding is slightly higher in elevation and older slides are increasingly mollified and dissected. Sliding appears to have ceased in the Holocene and intermittent streams are deeply incised.  The above diagram is taken from Strahler (1940).


Toe thrust of a landslide that has been dissected by surface streams


Schematic of a simple Toreva Toreva or slump block typical along the Vermilion Cliffs (from Huntoon, 1978).  This type of landslide exhibits rotational motion during movement.


Notice the back-rotated strata typical of Toreva-blocks along the front of the Vermilion Cliffs.

Questions or comments on this page?
E-mail Dr. J David Rogers at rogersda@umr.edu
or Conor Watkins at cwatkin@umr.edu.