Conor Watkins And J. David Rogers
Colorado Plateau Research
Vermilion Cliffs, AZ Landsliding
Use of Palynology To Date Landslides


USE OF PALYNOLOGY TO DATE LANDSLIDES


Some large headscarp grabens grabens behind the landslides formed closed depressions.  These basins trapped sediment washed down from the cliffs above, capturing pollens in the bottom of shallow ephemeral ponds.


The closed basins were eventually breached by headward erosion of adjacent streams. Gullies are presently being incised by intermittent watercourses, exposing old lacustrine sediments.


Most workers have assumed that reddish lacustrine lacustrine sediments in the Southwest are oxidized, which would destroy entrained pollen.  But the source units, the Kayenta and Navajo Formations, are also reddish in color.  Samples similar in appearance have been recovered from Grand Canyon and were found to contain pollens from a wide variety of species, as well as spores and freshwater algae.


Samples of fine grained sediments contained in several headscarp headscarp grabens have been recovered using a 1” diameter soil auger and plug sampler.


A 1” diameter soil auger can recover soil samples up to 1.5 m deep, or farther if subsurface conditions permit.  Palynology can be used to date the age of the ponds and therefore, the landslides.  It can also provide paleoecology and and paleoclimatology information which could information which could provide insights on why the slides occurred.

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