MMEW 2014 Field trips
Trip 1, June 18
Trip 2, June 19
Minnesota River Valley
Precambrian
Terranes
of Minnesota
The
Minnesota
River
Valley
Gneiss
Terrane
3.6-3.1 Ga
THE MINNESOTA
RIVER VALLEY
Actually it’s
3,485,000,000 years
±10,000,000
but hey, close enough
GRANITIC (= continental)
GNEISS (= high grade metamorphic)
Amphibolite
(oceanic crust?)
Geologic
Structure of
Southwestern
Minnesota
SMOG map
superimposed gravity
(color) on
aeromagnetics
(grayscale)
Yellow Medicine Shear Zone
A suture zone between
the Morton and
Montevideo Blocks?
Composed of garnet mafic
gneiss and amphibolite
(ocean crust in suture
zone?)
You are here.
From Pat Colgan
till
glacial stream
sediment
glacial lake
sediment
modern stream
sediment
780,000
years ago
Blue
spikes
represent
glacial
periods
1.66
million
years ago
2.58
million
years ago
Lisiecki and
Raymo, 2005
Series of
old tills on
Yellow
Medicine
River cut
Talk by former student and TA, Andy Breckenridge
…and it’s potential impact on global climate
Scour surfaces flanking main channel
You are here.
Low relief till plains and ice lobe troughs