• ES Picture of the Day 26 2020

    From Black Panther@21:1/186 to All on Thu Nov 26 11:00:46 2020
    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.


    Autumn on Laramidia’s Ancient Shore

    November 26, 2020

    Autumn on Laramidia’s Ancient Shore

    Photographer: Ray Boren
    Summary Author: Ray Boren

    During the Late Cretaceous Period — before the rise of North
    America’s Rocky Mountains, and before the Colorado Plateau emerged
    to geologically dominate the Four Corners region of Arizona, Utah,
    Colorado and New Mexico — a vast Western Interior Seaway covered
    much of the continent’s center, dividing it into two landmasses. The
    big islands have come to be called Appalachia (to the east) and
    Laramidia (on the west).

    A cliffy portion of the lithified western shore of that inland sea
    stretches across the background of the autumn-splashed photograph seen
    above taken along State Road 14, a scenic byway in upper Cedar
    Canyon above Cedar City, Utah. The shimmering leaves of Utah’s
    state tree, the quaking aspen ( Populus tremuloides), are
    revealing their inherent yellow pigments. Due to autumn’s chillier
    temperatures and declining daylight hours, they have ceased producing
    chlorophyll, which tints the leaves green in spring and summer.

    Sediments eroding from now-vanished mountain ranges to the west — on
    Laramidia which stretched from what is today Mexico to Alaska, and
    which gets its name from Laramie, Wyoming — were deposited in rivers,
    lakes and swamps along the seaway 66-100 million years ago. These
    transformed over time into Cedar Canyon’s tan-to-brown, cliff-forming
    sedimentary Straight Cliffs ( Tibbet Canyon Member) and
    Wahweap formations. These are also the oldest rocks in
    Cedar Breaks National Monument, just up the road, along what is
    today the edge of the Colorado Plateau’s western Markagunt
    Plateau. Photo taken October 15, 2020.

    Photo Details: Camera NIKON D3200; Exposure Time 0.0020s (1/500);
    Aperture ƒ/11.0; ISO equivalent 400; Focal Length (35mm) 30
    * Cedar Canyon, Utah Coordinates: 37.59442, -112.91643

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    Geology Links

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

    -
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    Space Research Association.

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