Cave system discovered under Montreal

[robkelk]

This is so cool... We've known for decades that there are caves under Montréal, but another set has been found!

http://www.cbc.ca/news/multimedia/explor...-1.4431920

And it's down at the level of the top of the local aquifer:

[DHBirr]

Looking at what appear to be 90° angles where the walls join a mostly-flat ceiling, it seems more like a human-made tunnel than a natural cave to me.  Are they sure no one was down there before, shaping it?

[robkelk]

Pretty sure, yes. Montreal's in the middle of the part of North America often covered by ice during ice ages - sedimentary rocks tend to be put down in layers that way. The nearly 90° angles are also caused by the most recent Ice Age - look up "glacial tectonism" (and, if you aren't a geologist, be prepared to spend hours figuring out what they're talking about).

[Labster]

I'm surprised it's snowing inside the cave.

Oh, wait, never mind.

[robkelk]

Yeah, c'mon - it's Canada.