Earth History
GEOL 2110
Midterm 2
Preparation/Review
Style of Questions
• Matching term w/ definition
• Short definition of concepts/processes
• Name some of multiple characteristics
• 25% of points from Part II Quizzes
REVIEW PowerPoints!!
Understand Figures in Text.
Focus on the Narrative – the great book of the
Earth, chapter by chapter.
The Precambrian
IN MINNESOTA
Know the Eons/Eras
4 Main Tectonic Events in MN
General Ages of the 4 main events
Characteristic rock types of the four
main events.
Continents formed from each event
Summary of Early Earth Events
Sudbury
Impact
SUPERCONTINENT - RODINIA
What causes break-up?
Contributions to the Cambrian
Explosion of Life
• End of the extreme snowball earth glaciation
• Tectonic break-up of Rodinia increases niches
• Potentially higher atmospheric O2 promotes
calcite exoskeleton secretion
• Increased nutrients associated with more rifting
and volcanic activity
• Abundant cyanobacterial mats for molluscs and
other small invertebrates to graze
• Development of predators
• Tiering of biotic activity on the sea floors
Paleozoic Era and its 8 Periods
KNOW
Cambrian
C
Chasing
• Order of Periods Ostriches
Ordovician
O
on
Silurian
STypes
•Characteristic Rock Sand
Devonian
D
• Paleogeography Dunes
Mississippian
M
Makes
•Depositional Environments
Carboniferous
Cathy
• Trangressive Sequences
Pennsylvanian
P her
Pee
•Characteristic Organisms
Permian
P
Pants
•Tectonic Events
Early Paleozoic Era
Early Paleozoic Era
Early Paleozoic Era
The Ordovician “Explosion”
Changes in Ordovician
from Cambrian Fauna
• more complex food
chain
• extend higher above
the seabed
• hard part made of
calcite rather than
phospate
Middle Paleozoic
Middle Paleozoic
Sedimentary Rocks and Depositional
Environments
Flysch
Molasse
Coal Beds
Evaporites (gypsum, halite)
High-angle Cross-bedded Sandstone
Organic Reef Complexes
Carbonates (limestone and dolostone)
Quartz sandstone
Shale and Siltstone
Iron Formation
Graywacke/Shale
Middle Paleozoic
The Age of Fishes
Plants colonize the land!
Invasion of the Land
Vascular Plants take Root
Late Paleozoic
Late Paleozoic
Late Paleozoic
Permian
Craton Tilts West / Seas Retreat / Climate Dries
Late Paleozoic – All Genera Established
The Great Permo-Triassic Extinction
90-95% of all marine species die out, and land life too
Proposed Causes
- Global cooling due to
Gondwana glaciation
- Reduced marine habitat due
to the creation of Pangea
- Extreme climatic changes
- Oxygen depletion due to
exposure of coal deposits
- Upwelling of CO2 from deep
ocean waters – hypercapnia
- Intense outpouring of basalt
in Serbia
NO EVIDENCE OF A METEOR
IMPACT AT LEAST!
Summary of Paleozoic Tectonics
Acadian/Caledonian
Appalachian/Hercynian
Gondwanaland
Taconian
North American Paleozoic Orogenies
REMEMBER IT’S ALL ABOUT THE STORY!
Good Luck!