Blue Eye of Africa
The Richat Structure from space looks like a giant blue eye in the Sahara Desert. This image has a 6-fold vertical exaggeration and some false color to better show the structure.
Amazing But True!
- Scientists first thought that the Richat structure was a meteorite impact crater.
- Scientists now say that the structure is a dome, like a circular anticline.
- Sedimentary rock layers with ages from late Precambrian to Ordovician make up the structure.
- The rocks dip outward at 10o to 20o.
- The rock layers that stick up are quartzite. The center is siliceous breccia.
- Igneous intrusive and extrusive rocks are found in the interior of the structure. A large igneous intrusion is thought to have uplifted the rocks.
With the links below, learn more about the Richat Structure. Then answer the following questions.
- Universe Today, Where in the Universe Challenge #22: http://www.universetoday.com/18572/where-in-the-universe-challenge-22/
- RadioCanada, Decouverte – L’enigme de Richat: http://www.youtube.com/watch?v=pTTnYRaZ55A
- How would scientists rule out the possibility that the Richat structure is a meteorite impact crater?
- What evidence would geologists look for that suggests that the feature is a dome?
- How is it possible to tell a circular anticline from a circular syncline?
- From the outside to the inside of the circle, where are the oldest rocks and where are the youngest rocks?
- How easy or hard is it to erode quartzite? How about the other types of sedimentary rocks found in the structure?