GEO 106 - Discussion Board 9

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Stony Brook University *

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106

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Astronomy

Date

Apr 3, 2024

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docx

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2

Uploaded by DrArtKookabura35

GEO 106 Discussion Board 9 Prompt: Earth has about 190 known impact craters. For your main post this week, you have to do some research about one of these craters and list the following information, citing your sources:  1)Name of the crater/impact structure and it's location. Note: You may  not  choose Meteor Crater/Barringer Crater in Arizona.  2)Size (radius or diameter) of the crater. 3)Approximate age of the crater.  4)Beyond the crater, what evidence exists for an impact (e.g., high pressure minerals (which ones?), shatter cones, impact glass, breccias, melt sheets)? In your response to others, provide a quantitative and qualitative comparison between the crater that you chose and the one chosen by the original poster. Note: don't respond to someone who chose the same crater as you.  Main Post: Impact craters help us learn more about the history of the Earth and our solar system. The impact crater I choose to talk about is the Nordlinger Ries Crater. 1) The Nordlinger Ries crater is located in western Bavaria, Germany. 2) It is a large circular depression with a diameter of roughly 15 miles (i.e. radius =~ 7.5 miles) (NASA) 3) Making use of radiometric dating and several other rock dating techniques it was found that the crater’s age is approximately 14.8 million years (LPI, 2020). 4) Some of the evidence suggesting creation from an impact event lie in the shape and the structure of the crater. Ries crater has a raised or uplifted center surrounded by an outer ring. The raised area is suggestive of being formed by rebound right after the impact by the rock, whereas the outer ring around the raised area is thought to have been created when the crater walls collapsed. Ries also has shatter cones that are found at the bottom of bed rock. They are fractures that are in the shape of cones and are formed due to high shock waves after an impact or an explosion. Ries also exhibits a variety of impactites, namely – impact melt rock, impact glass, and impact breccia. The composition of these rocks suggest that its texture and structure was altered due to an impact. Ries also has abundance of deformed shocked quartz grains, which is a sign of meteorite impacts. Lastly, the presence of a mineral element, Coesite, one that is formed under specific conditions of large meteorite impacts is also found at the Ries crater, adding to the evidence. These sources of information help strengthen the evidence for Nordlinger Ries Crater to be formed by an impact event in the distant past. Citations:
New evidence surrounding twin craters rocked by Mid-Miocene Impact Earthquakes . Lunar and Planetary Institute (LPI). (2020, December 28). Retrieved March 28, 2023, from https://www.lpi.usra.edu/features/122820/craters/  NASA. (n.d.).  Ries Crater, Germany . NASA. Retrieved March 28, 2023, from https://earthobservatory.nasa.gov/images/8554/ries-crater-germany  The Ries Crater Impactites . ERNSTSON CLAUDIN IMPACT STRUCTURES - METEORITE CRATERS. (2013, April 30). Retrieved March 28, 2023, from http://www.impact- structures.com/meteorite-impact-germany/the-ries-impact-structure-germany/the-ries- impactites/ 
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