Geologic TimeGeologic Time

Chapters:Chapters:

22,23,2422,23,24

Earth’s BeginningsEarth’s Beginnings

• 4.6 billion years ago– Collection of iron and gasses formed– Rotation of cloud caused planet to form

• Settling of iron to core

– Early atmosphere formed• Water vapor, carbon dioxide (CO2)

• Modern atmosphere Nitrogen (78%), Oxygen (21%), Argon (1%)

Theories of Earth ScienceTheories of Earth Science

• Uniformitarianism- Hutton- Small changes over a very long time.– Examples:

• Catastrophism- Large changes over small periods of time.– Examples:

MeteoritesMeteorites

• Crater Map

• Visual of crater

Geologic Time ScaleGeologic Time Scale

• Record of Earth’s History

• Eons- largest subdivision

• Eras- major subdivision

• Periods- Smallest divisions- made by types of life & geologic events.

Geologic Time Scale Con’tGeologic Time Scale Con’t

• Epochs- smallest subdivision- – Only found in

Cenozoic– Why???

• What is our Eon, Era, Period and Epoch now??

Pre- Cambrian TimePre- Cambrian Time

• Oldest and Longest Time Period

• Almost 90% of Earth’s History

• From beginning of Earth (4.6 billion years ago) to 540 Million years ago

• Oldest rocks are the deepest rocks

• Ores are deposited (iron, silver, gold)

Pre-Cambrian Con’tPre-Cambrian Con’t

• Atmosphere develops oxygen– How?

• Chemical reactions--- at least started process• Cyanobacteria

– Earliest life– Small (microscopic) blue-green algae– Not even a plant yet– Stromolites are their fossils

– Mass Extinction- Most of life dies (planets change) “an unusually large amount of species die in a short time

Phanerzoic Eon, Paleozoic EraPhanerzoic Eon, Paleozoic Era

• Paleo- (Latin) ancient; -zoic (Latin) animals/ life

• Hard shelled animals appear• Pangea formed• Plants begin to grow on land• “Age of Fish” large fish populate oceans• Amphibians (frogs) go to land• Insects appear

Paleozoic Con’tPaleozoic Con’t

• Pennsylvanian Period- very large swamps which later become coal

• Appalachian Mountains Form

Mesozoic EraMesozoic Era

• Meso- “middle” -zoic “animals/life”

• Breakup of Pangea• Age of Reptiles-

dinosaurs and reptiles rule planet

• Rocky Mountains form

Mass ExtinctionMass Extinction

• Dinosaurs are killed by meteorite

• Animals and plants change

• 90% of all species that have ever lived are now extinct

Cenozoic EraCenozoic Era

• Ceno- “new”; -zoic “life”

• Last 45 million years

• Age of Mammals- Humans evolve

• Ice Ages

• Flowering Plants

• Colorado Plateau and Sierra Nevada Mountains formed

Organic EvolutionOrganic Evolution

• Changes in the environment lead to changes in organisms

• Natural Selection- Certain traits make living in an environment easier

• Changes in Environment– Pangea moving→ climate → plants →animals

ExtinctionsExtinctions

• Species dies no more living organisms

• Cause each major divide in time scale

• Dinosaurs- meteor, change in plants