Key Concepts in Earth's Geological and Biological Evolution

Effects of having an atmosphere

Early atmosphere contained greenhouse gases. Controlled surface temperature, allowed liquid water, influenced albedo.

Evidence for atmosphere redox state

Banded Iron Formations (BIFs) show low oxygen in Archean oceans.

Cratons

Ancient, stable continental cores. Shields are exposed cratons.

BIFs

Iron layers deposited when oxygen was scarce; decline after oxygenation.

Boring Billion

Mesoproterozoic interval with little evolutionary innovation.

Snowball Earth

Global glaciations; evidence from glacial deposits and isotopes. Entry/exit tied to greenhouse gas buildup.

Cratons

Continued stability, foundation for continents.

Cambrian Explosion

Rapid diversification of body plans, hard parts.

Predator-Prey

Evolutionary arms race; predator strategies vs. defensive adaptations.

Lagerstätten

Exceptional fossil preservation sites.

GOBE

Great Ordovician Biodiversification Event.

Major evolutionary breakthroughs

Rise of fishes, land plants.

Controls on global climate

Albedo, greenhouse gases.

Evidence for glaciation

Glacial deposits, striations.

Major NA orogenic events

Appalachian orogenies.

Mass extinctions & drivers

End‑Permian.

Index fossils & extinctions

Trilobites.

Mesozoic Marine Revolution

Predators vs. prey defenses.

Dominant animals

Dinosaurs on land, marine reptiles in oceans.

Mass extinctions & drivers

End‑Cretaceous (Deccan Traps volcanism + asteroid impact).

Index fossils & extinctions

Ammonites, dinosaurs.

Climate evolution

Cooling trend; ocean circulation shifts (Drake Passage opening)

Controls on climate

CO₂ levels, albedo .

Horse evolution

Progressive changes in teeth/limbs with grassland expansion.

Late Cenozoic sea level change

Glacial cycles 9 sea level fluctuations.

Human evolution

From primates to Homo sapiens; tied to climate shifts.