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To: Robert A. Cook, PE
This whole Canadian Shield area, uncovered so long, and scraped clean only by glaciers but little other erosion and mountain building, is a living testimony to past impacts on the surface.

The text on the page with that image attributes that geology to a below-surface magma dome emplacement rather than an impact. I was surprised by that; I don't know how "informed" the description is.

5 posted on 03/13/2006 3:14:31 PM PST by cogitator
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To: cogitator; patton

Yes, I question that: Canadian Shield just doesn't have magma domes under it, which are typical of subduction zones and great seismic activity.

Rather the opposite in fact: A magma dome (like the unusual southern granite domes at GA's Stone Mountain and TX's Enchanted Rock don't "stay submerged" either - they are revealed as the surrounding softer rock is eroded away, not revealed by the ridges in overlaying rock.


7 posted on 03/14/2006 2:57:07 AM PST by Robert A Cook PE (I can only donate monthly, but Hillary's ABBCNNBCBS continue to lie every day!)
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