Geologic Story of Minnesota(as told by its rocks)

Part II: Phanerozoic

Rocks

Geologic TimescaleGeologic Timescale

Today’sToday’sLectureLecture

Evolution of the Penokean MountainsEvolution of the Penokean Mountains

St. CLOUDJAY COOKE

HIBBING

1,000,000,000 Years Ago1,000,000,000 Years AgoMinnesota becomes theMinnesota becomes the

stable interior of the stable interior of the North American ContinentNorth American Continent

500,000,000 Years Ago500,000,000 Years AgoShallow seas begin to Shallow seas begin to

periodically flood Minnesotaperiodically flood Minnesota

The Cambrian Explosion of LifeThe Cambrian Explosion of Life

Snowball Earth Snowball Earth The Trigger of the Cambrian Explosion??

The Carbon Cycle

Supercontinent Rodinia ~750 MaSupercontinent Rodinia ~750 Ma

Paleozoic Epicontinental SeasPaleozoic Epicontinental Seas

Geography of Middle Laurentia in Paleozoic TimeGeography of Middle Laurentia in Paleozoic Time

The Jordan SandstoneThe Jordan SandstoneUnconformityUnconformity

Missing FossilsMissing Fossils

Advanced TransgressionAdvanced Transgression RegressionRegression

Paleozoic Formations of the MidwestPaleozoic Formations of the Midwest

TwinCities

Ordovician Rocks of the Mississippi River BluffsOrdovician Rocks of the Mississippi River Bluffs

Mound Park

Minnehaha Falls

Ford Dam and Lock

P-Platteville Limestone G-Glenwood Shale S-St. Peter Sandstone

P

P

P

G--

G--

G--

S

S

S

Fossil Hunting in the Twin CitiesFossil Hunting in the Twin CitiesLilydale Park (the Brickyard)Lilydale Park (the Brickyard)

Paleogeography at theEnd of the Paleozoic

Extinctions at the End of the Paleozoic

SnowballEarth?

Western Interior SeawayWestern Interior Seaway

Cretaceous Deposits in Minnesota

Lignite and shale in southern Minnesota

Conglomerate and sandstone on banded iron formation in north-central Minnesota

Deeply weathered gneiss in Southwestern Minnesota

The The Coleraine Coleraine FormationFormation

High Sediment

Production

Low SedimentProduction

Why don’t Why don’t dinosaur dinosaur fossils occurfossils occurin Minnesota?in Minnesota?

The Break-up of Pangea

The Bedrock Geology of Minnesotais Complete