Plate Tectonics and the Rock Layers of Grand ... - Gsenmschool.org

Grand Staircase-Escalante National Monument Geology Unit 2
Student Activity
XIII. Claron Formation – Tc
Time formed
Rock
Location
Appearance:
Special features
Environment when
formed
Similar modern day
habitats
~50 mya, Cenozoic/Tertiary
Limestone, sandstone, siltstone
This formation is mostly in Dixie National Forest and Bryce
National Park.
Pale orange, yellow, pink white; 1000 to 1600 feet; weathers into
cliffs, spires, columns and pinnacles. Forms the Pink Cliffs of the
Grand Staircase.
Rapid erosion forms “hoodoos,” very colorful cliffs.
In a very large freshwater lake, sediments collected and consolidated
to form the Claron Formation. The pink member of the Claron is
predominantly river channel, flood plain, and lake deposits.
A large fresh water lake with high inflow, but little outflow.
Postscript
Paleogene time and Neogene time deposits are scattered throughout the Monument. These
materials rest on top of exposed rock strata and include:
• Lava flows and cinder cones form basalt, tuff, and ash layers.
• Wind blows sand into surface dunes, especially near eroding sandstone.
• Water washes debris, sand, and gravel into streambeds, terraces, and floodplains.
• Mass wasting creates talus slopes and rock falls.
• Wet shales collapse in landslides and slumps.
• Glaciers during the Pleistocene added materials later moved by water erosion.
And it Continues
Monument lands and the entire Colorado Plateau continue to rise in elevation. Tributaries to the
Colorado River keep wearing deeper into the canyons. Faults still move and erosion continues to
form windblown and waterborne deposits. Even human activities affect the geologic face of
GSENM. Its story is still being written.
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