Please enable JavaScript.
Coggle requires JavaScript to display documents.
A landscape associated with the action of ice sheets: Minnesota, Location …
A landscape associated with the action of ice sheets: Minnesota
Latitude 46 N
Longitude 50 W
Bordered to the west by North and South Dakota
Canada (Ontario) (North)
Wisconsin (East)
Iowa (South)
Geology
Landscape is part of the
Laurentian Shield
Metamorphic Gneiss, crops out along the
Minnesota River Valley
(Northern Part) Oldest rocks lie in alternating rocks
Volcanic + sedimentary rocks, granitic rock materials lie in areas around the belt
Volcanic formations lie throughout Laurentian Shield
Some Buried beneath
glacial deposits
North
Ancient Archaen granites and gneisses
The folding of these rocks make a mountainous (hilly) landscape
South West
Thick Layer of sedimentary rock
Erosional Impacts
Massive erosional power(Laurentide Ice sheet and lobes (Over 1 Km thick in places)
High mountains worn down (highest peak today only 500-700m)
Large ellipsoidal basin created (now studded with 1,000s of lakes) Example: Upper and Lower Red lakes (N. Minnesota)
NE region (Arrowhead region)-erosional basin is very deep (tectonic activity has exposed the weak shale rocks-eroded more rapidly (Lakes in region lie in deeply eroded shale)
Lobes of ice advanced-abrasion caused striations on the bare rock outcrops (greenstone). Alignment indicates direction of ice advance.
SE- not extensively covered with ice sheets-landscape more varied (steep hills and deep valleys). Rivers of area are tributaries of the Minnesota and Mississippi rivers.
Glaciation
75,000 years ago - lobes/tongues of ice extended form the main Laurentide ice sheet (spear through Minnesota)
Lobes advanced and retreated several times (transporting and depositing till)
Different origin of the lobes resulted in different tills (characteristics / material)
Location