Largest ancient meteorite impact found?
The uncertainty of science: Scientists doing geothermal research in Australia have discovered evidence of what they think is the largest known impact zone from an meteorite on Earth.
The zone is thought to be about 250 miles across, and suggests the bolide split in two pieces each about 6 miles across before impact. The uncertainty is that the evidence for this impact is quite tentative:
The exact date of the impacts remains unclear. The surrounding rocks are 300 to 600 million years old, but evidence of the type left by other meteorite strikes is lacking. For example, a large meteorite strike 66 million years ago sent up a plume of ash which is found as a layer of sediment in rocks around the world. The plume is thought to have led to the extinction of a large proportion of the life on the planet, including many dinosaur species.
However, a similar layer has not been found in sediments around 300 million years old, Dr Glikson said. “It’s a mystery – we can’t find an extinction event that matches these collisions. I have a suspicion the impact could be older than 300 million years,” he said.
In other words, they find some evidence that an impact occurred, but not other evidence that is expected to be found with such an impact. Moreover, the rocks at the sedimentary layer where the impact is found are dated around 300 million years ago, a time when no major extinction took place. Either this impact didn’t really happen, or it didn’t happen when it appears it should have, or it shows that large impacts don’t necessarily cause mass extinctions.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The print edition can be purchased at Amazon or from any other book seller. If you want an autographed copy the price is $60 for the hardback and $45 for the paperback, plus $8 shipping for each. Go here for purchasing details. The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
The uncertainty of science: Scientists doing geothermal research in Australia have discovered evidence of what they think is the largest known impact zone from an meteorite on Earth.
The zone is thought to be about 250 miles across, and suggests the bolide split in two pieces each about 6 miles across before impact. The uncertainty is that the evidence for this impact is quite tentative:
The exact date of the impacts remains unclear. The surrounding rocks are 300 to 600 million years old, but evidence of the type left by other meteorite strikes is lacking. For example, a large meteorite strike 66 million years ago sent up a plume of ash which is found as a layer of sediment in rocks around the world. The plume is thought to have led to the extinction of a large proportion of the life on the planet, including many dinosaur species.
However, a similar layer has not been found in sediments around 300 million years old, Dr Glikson said. “It’s a mystery – we can’t find an extinction event that matches these collisions. I have a suspicion the impact could be older than 300 million years,” he said.
In other words, they find some evidence that an impact occurred, but not other evidence that is expected to be found with such an impact. Moreover, the rocks at the sedimentary layer where the impact is found are dated around 300 million years ago, a time when no major extinction took place. Either this impact didn’t really happen, or it didn’t happen when it appears it should have, or it shows that large impacts don’t necessarily cause mass extinctions.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The print edition can be purchased at Amazon or from any other book seller. If you want an autographed copy the price is $60 for the hardback and $45 for the paperback, plus $8 shipping for each. Go here for purchasing details. The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News