Crater in NE Canada?, page 1

I was skimming a large North America map earlier today and noticed a circular river (or perhaps it'd be labeled a lake with a large central island), in North Eastern Canada. The lake/river has a diameter (stretching across the island) of about 45 miles.

external image

I was wondering if this type of geological formation would be formed by a large impact crater gradually filling with water over time, or is this simply an oddly shaped aquatic feature?

*Note: If you care to take a look yourself, the coordinates are in the lower left hand corner of the picture.

[Mod Edit = Please review: ATTN: Image Size Guidelines Image now links to full size version]

[edit on 4/2/06 by JAK]

You got that right, it's the Manicouagan Reservoir

There are quite a few others in Canada too. The harsh winters have preserved them, more or less.

Here is another crater in northern Quebec.

Google earth link: www.image-du-monde.com...

Pic: www.uqtr.uquebec.ca...

Here is another crater in northern Quebec.

Google earth link: www.image-du-monde.com...

Pic: www.uqtr.uquebec.ca...

Canada has a lot of craters in it. Of the 30 largest craters on Earth, being in size of 20 or more km in diameter, Canada has 10 of them. The largest being about 250 km in size.

First person to find them all wins a prize!

EDIT:

As for a crater chain on Earth, I couldn't find much. This was the best of which I found:

Crater Chains on the Earth and Moon

Recent work indicates that crater chains may exist on Earth as well. Eight circular depressions (3-17 km wide) distributed along a 700 km line across Kansas, Missouri, and Illinois may comprise part of a crater chain (M.R. Rampino and T. Volk (1996) Geophys. Res. Lett. 23, p. 49.) Two of the eight structures (Decaturville and Crooked Creek in Missouri) are known from field studies to be impact craters ~300 Myr old.

[edit on 2/6/2006 by cmdrkeenkid]

Heres a database of all know earth impact Craters

www.unb.ca...

Thats indeed a impact crater shows up " Manicouagan Quebec, Canada 100.00 KM exposed N 51° 23' W 68° 42' " in the data base. Third largest in North America

Originally posted by cmdrkeenkid
There are quite a few others in Canada too. The harsh winters have preserved them, more or less.

Of the 30 largest craters on Earth, being in size of 20 or more km in diameter, Canada has 10 of them.

Winter doesn't preserve anything except things which need freezing to prevent rotting.

Freezing water grinds top of bedrock very effectively and can literally split stones in half, only hardest and least porous rocks can withstand it without fast eroding.


Reason's for amount of craters in Canada are entirely others, first of all it's very big country.
Then even more important thing considering big hits is that parts of Canada belongs to group of areas with very old continental crust. (impacts, especially bigger, were more common earlier history of Earth)
And this old means place where 1.5 billion years old rocks are young ones.

en.wikipedia.org...
Other similar area is Baltic shield.
Both of these areas are some of the oldest continental crust parts and contain remnants of ancient mountain ranges similar to Rocky mountains, Himalaya, Alps... it's just that those mountains have eroded away and now there's only "roots" of them left.

Here in Finland problem is that bedrock older than 2 billion years old has been involved in so many folding and faulting processes that possible older craters have been destroyed about completely. (lines show just biggest faults and collision zones)

If someone wants to practise finding craters from satellite photos craters in Finland should show nicely what eroded craters can look.
maps.google.com...

Originally posted by cmdrkeenkid
GoldEagle, I don't believe that that's a crater though. I've never heard it called one before, thought it may be worth digging in to. Those islands in and near the center of the circle could be the results of a complex crater.

Also I've read one book in which it was listed as possible crater.

Finding signs of impact should be easy... Glaciers have even scraped away any softer material from top of bedrock so there shouldn't be much digging required.


For that sized crater there should be plenty of visible signs in rocks, actually the bigger the crater the stronger the signs are.
And signs stay in bedrock much longer than eroding crater bowl takes...

Here's some pics of shatter cones from "crater" which might be just base of central peak.
www.somerikko.net...

That island chain along coast could be explained by multiple rims.
But those islands inside it are such that it would require quite big central peak, neither they are in center... but impact in shallow angle can cause such. (but then again rim seems to be very symmetric)

Also on other hand it should have been very easy to find proofs for it being impact crater considering size.

I got a list of all the big known impact sites in the world here:

www.unb.ca...

The largest currently listed is in South Africa. The one in Sudbury is probably a good part of the reason the world's richest nickel mines are all there.

There's still some debate about Hudsons Bay, if it is, it would be the largest in the world at 440 km across, but there's no other surface stresses outside of that area that would indicate a massive impact. The lack of evidence doesn't rule it out either though.

Originally posted by berglion
I got a list of all the big known impact sites in the world here:

www.unb.ca...

That definitely isn't full list, it lacks at least other "half" of Suvasvesi double crater.
Here's little longer list including some meterite falls and known airblasts.
www.somerikko.net...

And list of suspected craters plus structures with other reasons than impact more propable.
www.somerikko.net...


Wikipedia lists one very big hypothetized crater called Shiva in West India but that size impact would cause huge ejecta layers

While moon has plentiful amount of big hits problem for finding those in Earth is erosion and tectonic processes, most of moon's craters are billions years old but lack of these processes has preserved them.
Also oceans cover over two thirds of Earth and when you remember that oldest sea floors are just few hundred million years old because oceanic crust is in slow constant "circulation" where new crust is created in middle ridges of oceans while oldest parts get subducted under continental crust and back to mantle it's clear that this process alone has destroyed big amount of craters.


For example here's map/list of known and suspected craters/structures in Fennoscandia... problem is just that these areas have been treated in such way that finding any proves to direction or other from old (and big) structures would like trying to recognize make of car crushed between two colliding trains.
www.geophysics.helsinki.fi...

Originally posted by berglion
The one in Sudbury is probably a good part of the reason the world's richest nickel mines are all there.

Speaking of that when you look map of previous link and crater/structure number 88 and compare it to satellite photos available in here there's very clear semi circular structure there.
Also this place has considerable nickel concentrations, in fact there's city named as Nickel because of mines.
While most of this area contains lot of minerals rocks crushed porous by impact could well provide good base for enriching of certain minerals by geological processes.



Also there seems to be other suggested reason... basing to fact that lower crust contains more minerals.
www.news.utoronto.ca...

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