At first, the Richat Structure was thought to have been formed by a meteor impact. Upon further review, it was found to not have the features of such an impact. Consequently, it now is thought to be a circular anticline. It consists of Paleozoic quartzites. Erosion removed the sand, but the quartzite is much more resistant to erosion.
As depicted on Nasa's Earth Observatory site:
This true-color scene was acquired by the Moderate-resolution Imaging Spectroradiometer (MODIS), flying aboard NASA’s Terra satellite, on March 11, 2002.This is the sort of image we are accustomed to seeing. Now there is one that is more interesting, posted on Wikipedia. (Below the fold, of course...)
In order to fully appreciate it, you might want to see the high resolution version (2259x1244, 495 KB). Part of the image was taken during the Shuttle Radar Topography Mission, and part is a Landsat image; the two were combined,as described on the JPL site:
This view was generated from a Landsat satellite image draped over an elevation model produced by the Shuttle Radar Topography Mission (SRTM). The view uses a 6-times vertical exaggeration to greatly enhance topographic expression. For vertical scale, note that the height of the mesa ridge in the back center of the view is about 285 meters (about 935 feet) tall. Colors of the scene were enhanced by use of a combination of visible and infrared bands, which helps to differentiate bedrock (browns), sand (yellow, some white), minor vegetation in drainage channels (green), and salty sediments (bluish whites). Some shading of the elevation model was included to further highlight the topographic features.
In other words, the Structure does not really look like the picture. But it sure is a nice image. I don't think it is frivolous, even though it is not a literal depiction of the Structure. It shows what kinds of things can be done with this kind of imaging, to enhance the pictures. This can have practical applications, in addition to making pretty pictures.
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