March 5 meeting in Arnprior explores meteorite impacts through geological time
Some 66 million years ago, dinosaurs like the T. Rex and Triceratops populated the lush tropical forests that blanketed what is now Western Canada. Until, that is, a catastrophic event obliterated them and half of Earth’s species.
Dr. John Percival, senior research scientist at the Geological Survey of Canada (GSC), unpacks what happened:
“A 10- to 15-kilometre diameter meteorite travelling at 10 kilometres per second struck the Yucatán Peninsula in present day Mexico, vaporizing rocks within a 150-kilometre wide, 20-kilometre deep crater. Rock vapour enveloped the globe, resulting in the extinction of about half of Earth’s species, including the dinosaurs. This crater, called the Chicxulub Crater, is now covered with sediments and seawater.”
Percival reassures us: “While there is an almost continuous rain of interplanetary dust, regular meteorite showers and occasional fireballs entering the atmosphere, only rarely do objects large enough to excavate craters strike the Earth.”
Learn more at the March 5 Macnamara Field Naturalists Club (MFNC) meeting, when he will present Meteorite Impacts Through Geological Time, an illustrated tour of such impact events, including notable Canadian craters like the closest one, the 450-million-year-old Brent crater in eastern Algonquin Park, known for its perfect circular crate; the 1.4-million-year-old Pingualuit crater within the Ungava Peninsula in far-north Quebec; and the richest one, the 1.85-billion-year-old Sudbury structure.
Some unearthed nuggets:
• The vast majority of meteorites are pieces of asteroids, the small rocky bodies that orbit the Sun, mostly between Mars and Jupiter. American Museum of Natural History
• Small meteors regularly impact the Moon and Earth. On Earth, they usually burn up in the atmosphere, or land in uninhabited areas where they go undetected. But, on the moon, they constantly form craters and impact basins. New Scientist
• Observers who closely watched the recent Super Blood Wolf Moon eclipse spotted an extra bonus: A meteoroid flying into the surface of the moon, mid-eclipse. Check out this video clip. [http://digg.com/2019/super-blood-wolf-moon-meteor-strike]
• A Mars-sized meteor is thought to be responsible for striking the primitive Earth, ejecting material that became the Moon about 4.53 billion years ago. John Percival