Glaciers

[stephaniemb2]

could someone tell mewht kind of sedimaents were deposited in  northern Minnesota by glacaition?

[Clanad]

Sediments deposited by retreating glaciers form tills...the composition of the till depends on the rocks that serve as its source.  The identification of the rocks found in tills can inform one of where the glacier came from as it retreated.  Ridges formed at the sides or ends of tills are called moraines. Two major troughs channeled the Laurentide Ice Sheet through the area to become Minnesota. In northeastern MN near the Superior Basin deposits of reddish brown to dark brown coarse grained igneous and metamorphic rocks containing iron ores were deposited.  Farther west, deposits of yellow brown rocks dominated by sedimentary fragments from the Paleozoic and Cretaceous eras were laid down. 

This consitutes a very simplified description of a complex geologic phenomena that occurred between 75,000 and 12,000 years ago...

[New Forester]

That's the last glaciation -- there were of course many earlier ones, and of course there still are glaciers and ice sheets today which still do it.  For the moment at least, but then only if someone does something about global warming sharpish.

 

One form of glacial sediment is boulder clay, found throughout lower parts of Britain north of London.  In that case it's the mashed up remains of The North, pushed along under a mile or two thick of ice sheet.

 

Don't know about Minnesota though.