10 May 2012
.JPG)
Fig. 1
The image, acquired by an astronaut aboard the International Space Station, shows a large impact crater in Algeria.
Credit: NASA-JSC
NASA recently published an interesting image (Fig. 1) of the Ouarkziz Crater, an impact crater located in northwestern Algeria, close to the border with Morocco. Ouarkziz was produced by a powerful meteorite impact, less than 70 million years ago, near the end of the Cretaceous Period, or “Age of Dinosaurs.”
Ouarkziz (3.5 km across), located in image center, has been largely eroded since its formation; however, its circular shape is highlighted by exposed, older sedimentary rock layers that form ridgelines. From the vantage point of an astronaut onboard the International Space Station, orbiting about 350 km above Earth’s surface, the impact crater is obvious with a telephoto camera lens.
A geologist interpreting this image to build a geological history of the region would conclude that the Ouarkziz crater is younger than the sedimentary rocks, as the rock layers had to be already present for the meteorite to hit them.
References
NASA Earth Observatory
http://earthobservatory.nasa.gov/IOTD/view.php?id=77851
Aymen Mohamed Ibrahem
Senior Astronomy Specialist