Geology in the News
World's Oldest Impact Site
24 January 2020
Scientists recently announced confirmation of the world's oldest impact site, found east of Perth in western Australia. It's 2.2 billion years old. It's not really a crater after so long, It was found because of geophysical anomalies in the area.
Interestingly, it's thought the Earth was undergoing a "Snowball Earth" phase at the time, with pole-to-pole glaciation. They theorize that the impact of this meteorite could have triggered greenhouse gasses to start warming the planet and melting the ice.
Arizona's oldest rocks are schists that date to 1.6 billion years. One of them is the Pinal Schist named for a location in our county. The other Arizona schist of that age is at the very bottom of the Grand Canyon.
When this meteorite landed, Arizona was under the ocean, and located at approximately the South Pole.
You can find the BBC article on the impact site at: https://www.bbc.com/news/world-australia-51201168
A "New" Allosaurus
24 January 2020
Allosaurus jimmandsi is a new dinosaur named from the Morrison Formation at Dinosaur National Monument in Utah.
The name has been around for quite awhile, so you may have heard of it before, but ithis is the formal naming and description.
Though found in Utah, other species found in the same area have been found in Arizona, so it's quite possible this could be added to the dinosaurs of Pinal County. It lived about 5 million years before the more common Allosaurus fragilis.
A new dinosaur species is named and described about every 7 weeks. There are only about 750 species known, which is just a small fraction of the dinosaurs that probably existed.
Image from the article.
Read the article at: https://peerj.com/articles/7803/?fbclid=IwAR1Ay5C3nYLsBn5_wUCfBTPrW8_KWI2Z8p4-hdUQ3vUoetBWty8W5RkXEJ8
2020. Cranial anatomy of Allosaurus jimmadseni, a new species from the lower part of the Morrison Formation (Upper Jurassic) of Western North America. PeerJ 8:e7803 https://doi.org/10.7717/peerj.7803
