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Geology, Palaeontology & Archaeology / Re: Partially submerged unverified crater in the Great Slave Lake of Canada Perhaps?
« on: 12/03/2012 00:30:16 »
a moraine is unconsolidated material.
What you are seeing in the photo is all basically bare bedrock including the semi-circle, because you are looking at part of the Canadian Shield - as the wiki says - The North American craton is the bedrock forming the heart of the North American continent and the Canadian Shield is the largest exposed part of the craton's bedrock.
When it comes to round land forms that are natural craters are not rare, but CONFIRMED craters are rare.
Confirmation requires several different things be found at the site.
If nothing known to be a result of an impact can be found then other explanations are used as in the semi-circle formation in the Hudson Bay to the East of this.
Confirmation is NOT free. To actually send out a team to simply prove or disprove an object is an impact site can be prohibitively expensive especially when it's to a location as remote as the Great Slave Lake.
Without greater justification it's not going to happen. So it's nature is left undetermined.
Undetermined is NOT the same as NOT being something.
While there are quite a few landforms that could very well be impact sites, most go undeclared, because no mission has been set up specifically to prove or disprove this.
Probably the vast majority of "confirmations" re impact sites were the result of work being done in a location for reasons UNrelated to proving it was an impact site, like searching for oil or other minerals to exploit. While doing that work, a keen eyed geologist would notice that the rocks they were examining exhibited evidence associated with an impact.
That's how the totally UNDERGROUND impact sites are found with sheer luck, not purpose.
So your skepticism based on the "rarity of impacts" is not justified.
If you note I said PERHAPS in my headline.
I did not say I knew either, but that the shape reminded me of several well known craters have been confirmed also located in the Canadian shield. Do a search for clearwater lakes meteor crater and you'll see the extreme similarity.The parallel striations you think so important are found on quite a few meteor craters of great age. If anything that's more evidence that it probably is (Arounga, Gosse's Bluff.
If you had taken a moment before you decided I had to be wrong to look at them you'd be hard pressed to deny the similarity in appearance.
Considering that the shape of this object conforms quite nicely to those craters that have been confirmed in that location to think this might be another impact site is not far fetched at all.
Oddly the option you quickly dismissed that it might be volcanic in origin is also far better than a moraine or anything else, for as the fullwiki says - The Shield was originally an area of very large mountains (about 12,000 metres or 39,000 feet)[7] with much volcanic activity, but over the millennia the area was eroded to its current topographic appearance of relatively low relief. It contains some of the most ancient volcanoes on Earth. It has over 150 volcanic belts (now deformed and eroded down to nearly flat plains) that range from 600 to 1200 million years old.
It could very well be a submerged caldera with only part of its rim showing, but if it is, it is one of the roundest ones in evidence.
To demonstrate how "round" the semicircle is I doubled it and stuck it together in paintnet.
What you are seeing in the photo is all basically bare bedrock including the semi-circle, because you are looking at part of the Canadian Shield - as the wiki says - The North American craton is the bedrock forming the heart of the North American continent and the Canadian Shield is the largest exposed part of the craton's bedrock.
When it comes to round land forms that are natural craters are not rare, but CONFIRMED craters are rare.
Confirmation requires several different things be found at the site.
If nothing known to be a result of an impact can be found then other explanations are used as in the semi-circle formation in the Hudson Bay to the East of this.
Confirmation is NOT free. To actually send out a team to simply prove or disprove an object is an impact site can be prohibitively expensive especially when it's to a location as remote as the Great Slave Lake.
Without greater justification it's not going to happen. So it's nature is left undetermined.
Undetermined is NOT the same as NOT being something.
While there are quite a few landforms that could very well be impact sites, most go undeclared, because no mission has been set up specifically to prove or disprove this.
Probably the vast majority of "confirmations" re impact sites were the result of work being done in a location for reasons UNrelated to proving it was an impact site, like searching for oil or other minerals to exploit. While doing that work, a keen eyed geologist would notice that the rocks they were examining exhibited evidence associated with an impact.
That's how the totally UNDERGROUND impact sites are found with sheer luck, not purpose.
So your skepticism based on the "rarity of impacts" is not justified.
If you note I said PERHAPS in my headline.
I did not say I knew either, but that the shape reminded me of several well known craters have been confirmed also located in the Canadian shield. Do a search for clearwater lakes meteor crater and you'll see the extreme similarity.The parallel striations you think so important are found on quite a few meteor craters of great age. If anything that's more evidence that it probably is (Arounga, Gosse's Bluff.
If you had taken a moment before you decided I had to be wrong to look at them you'd be hard pressed to deny the similarity in appearance.
Considering that the shape of this object conforms quite nicely to those craters that have been confirmed in that location to think this might be another impact site is not far fetched at all.
Oddly the option you quickly dismissed that it might be volcanic in origin is also far better than a moraine or anything else, for as the fullwiki says - The Shield was originally an area of very large mountains (about 12,000 metres or 39,000 feet)[7] with much volcanic activity, but over the millennia the area was eroded to its current topographic appearance of relatively low relief. It contains some of the most ancient volcanoes on Earth. It has over 150 volcanic belts (now deformed and eroded down to nearly flat plains) that range from 600 to 1200 million years old.
It could very well be a submerged caldera with only part of its rim showing, but if it is, it is one of the roundest ones in evidence.
To demonstrate how "round" the semicircle is I doubled it and stuck it together in paintnet.