https://earthobservatory.nasa.gov/images/92071/richat-structure

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Richat Structure

Richat Structure

December 17, 2011JPEG

The Richat Structure of Mauritania has captured the attention of
astronauts for about as long as NASA has sent humans into orbit
around Earth. This circular geologic feature is thought to be caused
by an uplifted dome--geologists would classify it as a domed anticline
--that has been eroded to expose the originally flat rock layers.

In this type of geologic structure, rocks exposed in the center of
the "bullseye" are older than rocks forming the outer rings. This
structure measures 45 kilometers (28 miles) across and is made up of
igneous and sedimentary rocks. There are several faults visible
(lower left) where strata that were once continuous have been shifted
apart.

Most of Mauritania lies within the Sahara Desert, where dry climate
conditions and periodic droughts create difficult living conditions.
Approximately 3.7 million people live in Mauritania, though much of
the population lives along its Atlantic coastline, about 500
kilometers (300 miles) from the Richat Structure.

Astronaut photograph ISS030-E-12516 was acquired on December 17,
2011, with a Nikon D2Xs digital camera using a 400 millimeter lens
and is provided by the ISS Crew Earth Observations Facility and the
Earth Science and Remote Sensing Unit, Johnson Space Center. The
image was taken by a member of the Expedition 30 crew. The image has
been cropped and enhanced to improve contrast, and lens artifacts
have been removed. The International Space Station Program supports
the laboratory as part of the ISS National Lab to help astronauts
take pictures of Earth that will be of the greatest value to
scientists and the public, and to make those images freely available
on the Internet. Additional images taken by astronauts and cosmonauts
can be viewed at the NASA/JSC Gateway to Astronaut Photography of
Earth. Caption by Andrea Meado, Jacobs Technology, JETS Contract at
NASA-JSC.

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This geologic feature has captured the attention of astronauts for
about as long as NASA has sent humans into orbit around Earth.

Image of the Day for April 29, 2018

Instrument:
    ISS -- Digital Camera

Appears in this Collection:
    Astronaut Photography

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