Wednesday, February 27, 2013

USGS geologic map of US 89 Bitter Springs landslide area

Ancient landslides are extensive in the Echo Cliffs where last week's landslide destroyed a section of US 89.

The February 20 Bitter Springs landslide occurred within the boundaries of the Glen Canyon Dam 1:100k sheet. This was mapped by George Billingsley of the US Geological Survey in Flagstaff and has been peer reviewed, but is still pending USGS publication.

In response to the need for quick geologic information, the USGS released draft copies of the map to AZGS and ADOT to help us better assess the geologic situation.

The map at right is a small piece excerpted from the full map.   The arrow points to the general area of the new landslide.  "Ql" are Quaternary aged landslide deposits.  Note the large block on the hillside to the right (upslope) of the highway. Note also the extensive landslide deposits that cover much of the western slope of the Echo Cliffs.

This information is preliminary and is subject to revision. It is being provided by the USGS to meet the need for timely best science. The information is provided on the condition that neither the U.S. Geological Survey nor the U.S. Government may be held liable for any damages resulting from the authorized or unauthorized use of the information.

Thanks to the USGS for making these materials available to us. 

1 comment:

  1. Not to be snarky, but, in this digital age, 7 days to provide an already-completed map in response to a hazard taking out an interstate is not quick, it's embarrassing.