Tuesday, May 13, 2008

Modis image of Great Lakes

This is on the Nasa Modis site. It's a great shot of the Michigan Basin, which I think is one of the most mysterious geological phenomenon of this area.

Here, in the middle of a 'rock-solid' continent, is a big basin that slowly sunk to the centre of the earth (to the Moho, at least!). What caused this? Note the circularity of the lake shorelines around it. All the region got sucked into this, including my fav. Bruce site. I've studied it, but have never understood it.

There, wasn't that a good intellectual break from disasters, and general political incompetence?


Monado said...

Ancient salt dome melting away? We did have oceans here once.

What other possibilities are there?

Beautiful picture, anyway.

Harold Asmis said...

Just something about the tectonics at the time that opened up this big circular hole.