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!