MMEW 2014 Field trips
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Transcript of MMEW 2014 Field trips
MMEW 2014 Field tripsTrip 1, June 18Trip 2, June 19
Minnesota River Valley
Precambrian Terranes
of Minnesota
The Minnesota River Valley Gneiss Terrane3.6-3.1 Ga
THE MINNESOTARIVER VALLEY
Actually it’s3,485,000,000 years
±10,000,000but hey, close enough
GRANITIC (= continental)
GNEISS (= high grade metamorphic)
Amphibolite (oceanic crust?)
Geologic Structure of Southwestern Minnesota
SMOG mapsuperimposed gravity
(color) on aeromagnetics
(grayscale)
Yellow Medicine Shear Zone
Composed of garnet maficgneiss and amphibolite (ocean crust in suture zone?)
A suture zone between the Morton and Montevideo Blocks?
You are here.
From Pat Colgan
till
glacial stream sediment
glacial lake sediment
modern stream sediment
Lisiecki and Raymo, 2005
Blue spikes represent glacial periods
780,000 years ago
2.58 million years ago
1.66 million years ago
Series of old tills on
Yellow Medicine River cut
…and it’s potential impact on global climate
Talk by former student and TA, Andy Breckenridge
Scour surfaces flanking main channel
Low relief till plains and ice lobe troughs
You are here.
MAKE THE MOST OF IT!