[meteorite-list] WHAT OCCURS IN A LARGE HYPERVELOCITY IMPACT ON AN ICE SHEET?

From: E.P. Grondine <epgrondine_at_meteoritecentral.com>
Date: Wed, 20 May 2015 19:27:53 -0700
Message-ID: <1432175273.24405.YahooMailBasic_at_web125506.mail.ne1.yahoo.com>

If it is evidence of an impact, it may have happened during the last ice age, when the area around Lloydminster was under a huge mass of ice.

Ollen's theory, and he stresses that's "all it is" is a large asteroid hit and melted the thick ice above the area, likely not even reaching the ground.

[epg - I don't think so. Not for this size of blast.]

http://www.meridianbooster.com/2009/03/18/did-a-massive-meteor-touch-down-here

Sunday, March 22, 2009
Lloydminster Meridian Booster

In the first of my notes to the list, I speculated on the timing of the beginning of the Holocene Start Impact Event. In this note, I move on to consider some possible geological evidence, and call attention to an earlier comment by David Ollen on the mechanics of large hypervelocity impacts onto ice sheets.

DID A MASSIVE METEOR TOUCH DOWN HERE?
Posted By Graham Mason
Posted 4 days ago

It's just a theory, but it's an interesting one.

David Ollen may have found evidence of a massive impact crater just south of Kitscoty, but it doesn't look anything like what you might expect.

Instead of a huge hole in the ground, it's a circular plateau about 30 kilometres in diameter, with an inner circle about 12 kilometres in diameter.

With this evaporation, a great weight was lifted from the land and, combined with the heavy ice still around the impact's circumference, caused the land under the hole in the ice to rise 50 to 100 feet.

"When you have three-quarters of a mile of ice over an area there's a lot of pressure there," he said. "That ice is heavy. When you all of a sudden bang it and evaporate half of it, it takes the pressure off but the pressure is still on around it.

"If all of a sudden you knock the ice out of the spot, it's going to pop up."

Ollen noticed the anomaly while looking at topography maps to determine Internet availability for households in the area.

"We are an Internet service provider and we subscribe to a website that has a topography map on it and we use those maps to tell people whether they can get access rather than driving all the way to a place and telling them we can't reach it, said Ollen. "I thought about it for a little while and figured a few things out over the weekend, I thought I may as well send it to Discover Magazine and the Booster as well.

"It's a big impact, 30 kilometres across. That's a heck of a big asteroid."

Ollen said he'd be interested in knowing what a professional would have to say about it.

"I've been a science nut since I was a kid. They used to call me "Anti-matter Dave" when I was in school," said Ollen. "I've always been interested in science and archeology and geology and anything to do with science."

"It's just a curiosity, it might be wrong it's just an interesting theory."

*END OF ARTICLE QUOTE*

If this is not the first impact of the Holocene Start Impact Event, or one of the impacts in it, this geobleme bears the signs of perhaps being generated by a large hypervelocity impact which must have occurred during the last ice age. If it is the remains of a volcanic plug, would not the ice sheet would have scoured it away during it's advance?

If this geobleme was not generated by a comet impact, but instead from an asteroid impact, then perhaps bits of the impactor lie surrouding the area, and good hunting, everone.

In either case, it strikes me that the water would cool the plasma and wash the impactites out of the atmosphere almost immediately, along with any cosmic dust loading from a comet's debris stream.

Obviously, looking at the water flows of the river drainages should help to pinpoint the location of any ice sheet impact during the last ice age. Such as the one the Choctaw remembered.

{Sterling, can you work the numbers for comet impact on an ice sheet, and give us some rough estimates for force of the impact and the volume of water released? The range for 1.8 atmpospheres overpressure, the kill zone, would also be interesting. I think that no one has ever done a proper estimate for the Meteor Crater kill zone. )

all the best,
Ed
 
Received on Wed 20 May 2015 10:27:53 PM PDT