Subj : ES Picture of the Day 03  2022
To   : All
From : Dan Richter
Date : Wed Aug 03 2022 12:01:06

 EPOD - a service of USRA

The Earth Science Picture of the Day (EPOD) highlights the diverse processes
and phenomena which shape our planet and our lives. EPOD will collect and
archive photos, imagery, graphics, and artwork with short explanatory
captions and links exemplifying features within the Earth system. The
community is invited to contribute digital imagery, short captions and
relevant links.


 Mantling on Utah’s Hogback Ridge

   August 03, 2022

    TomMc_EPOD.MantlingHogbackRidgeUtahMcGuire (002)

    TomMc_EPOD.LowerCalfCreekFallsMcGuire (4) (002)_a

   Photographer:  Thomas McGuire

   Summary Author:  Thomas McGuire

   For 5 miles (8 km), Utah’s  Route 12. between Escalante and Boulder,
   Utah, follows the narrow 1,000 ft (305 m) high  Hogback Ridge of
    Navajo Sandstone. Spectacular long  views on either side of this
   highway show tan-to-white-to-yellow Navajo  'slickrock'. The ridge
   is also bounded by deep canyons: One is Calf Creek, with two impressive
   waterfalls (bottom photo); on the opposite side is  Boulder Creek,
   with narrow slot canyons.

   But there’s a clear sign of something missing. Part of the ridge is
   strewn with giant boulders of basalt. Clearly there were lava flows
   that covered the Navajo Sandstone along an unknown part of the ridge
   and probably much more. For most of the 5 miles (8 km), all that’s left
   are the lava-boulders  mantling the sandstone.

    Basalt is very resistant to weathering and erosion, so it forms the
   cap rock of many flat-topped mesas in the Southwest. As the sides of
   the mesa erode back, basalt boulders fall from the top and cover the
   slopes along with the underlying rock type that make up the body of the
   mesa. An observer can be forgiven for thinking the whole mountain is
   basalt when the bulk of the bedrock is hidden beneath its thin mantle
   of basalt and boulders, which will completely erode away with
   (geologic) time. When this happens, there’ll be no record of the lava
   flows that once covered significant areas around Hogback Ridge.


   Hogback Ridge, Utah Coordinates: 37.8144, -111.4091


Related EPODs

    Mantling on Utah’s Hogback Ridge  Dendrite Inclusion in Opal
    New Eddystone Rock  Varvite Park in Brazil  Volcanic Tunnels
   of Reunion Island  The Castles of the Calchaquíes Valleys
    More...

Geology Links

     *  Earthquakes
     *  Geologic Time
     *  Geomagnetism
     *  General Dictionary of Geology
     *  Mineral and Locality Database
     *  Mohs Scale of Mineral Hardness
     *  This Dynamic Earth
     *  USGS
     *  MyShake - University of California, Berkeley
     *  USGS Ask a Geologist
     *  USGS/NPS Geologic Glossary
     *  USGS Volcano Hazards Program

-
   Earth Science Picture of the Day is a service of the  Universities
   Space Research Association.

https://epod.usra.edu
 
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