Time- a limited period or interval, as between two successive events.

Seconds

Minutes

Hours

Days

Years

1. 1. Relative Time- subdivisions of the Earth's geology in a specific order based upon relative age relationships. These subdivisions are given names, most of which can be recognized globally, usually on the basis of fossils.

Example: Thanksgiving is between Halloween and New Year’s Eve.

Fossil- remains, impressions, or other evidence of life preserved in rock.

1. 2. Absolute Time- numerical ages in "millions of years" or some other measurement. These are most commonly obtained via radiometric dating.

Example: The school year is 180 days long.

mya = millions of years agobya = billions of years ago

Example: The following are equal amounts of time3,800,000,000 years ago3,800 mya 3.8 bya

The Earth is thought to be 4.6 billion years old.

Can you grasp how big 1 billion is???

Hmmm…….Lets put it in perspective!

Geologic Time Scale

Subdivided into segments of time:

Eon

Era

Period

Epoch

Largest

Smallest

Geologic Time Scale

Subdivided into segments of time:

3-Eons PhanerozoicProterozoicArchean

Youngest

Oldest

Geologic Time Scale

Subdivided into segments of time:

Phanerozoic CenozoicDivided into 3 Eras Mesozoic

Paleozoic

Youngest

Oldest

Eon Era

Geologic Time ScaleSubdivided into segments of time:

Phanerozoic Cenozoic

Mesozoic

Paleozoic

Youngest

Oldest

Eon EraPeriod

Quaternary

Tertiary

Cretaceous

Jurassic

Triassic

Permian

Carboniferous

Devonian

Silurian

Ordovician

Cambrian

NeogenePaleogene

PennsylvanianMississippian

Geologic Time ScaleSubdivided into segments of time:

Phanerozoic Cenozoic

Mesozoic

Paleozoic

Youngest

Oldest

Eon EraPeriod

Quaternary

Tertiary

Cretaceous

Jurassic

Triassic

Permian

Carboniferous

Devonian

Silurian

Ordovician

Cambrian

Holocene

Pleistocene

Pliocene

Miocene

Oligocene

Eocene

Paleocene

Epoch

Geologic Time Scale- summary of major

events in Earth’s past that are preserved in the

rock record.

Based on relative and absolute time.

Found on pages 8-9 in your

ESRT

Hadean Eon

Accretion disc Meteorite

Hadean Eon4.5 to 3.8 billion years ago

•Pre-dates the Earth

•No rocks on Earth are this old, except for meteorites

•Solar system formation

•Earth turned from molten to solid about 3.8 bya

•Earth began forming “protocontinents” in the Achean Eon

430 Million Years Ago!

New York

Diatoms

Trilobites

540-250 million years ago

Eurypterids

Horseshoe Crabs

Eurypterids

Stomatolites

Cycads Today Cycad Fossils

Dinosaurs

Oldest Archean: Greek for “ancient”

Proterozoic: Greek for “earlier life”

Youngest Phanerozoic: Greek for “visible life.” We are currently in the Phanerozoic Eon.

1. Eon- the largest segment of geologic time.

Oldest Paleozoic: “old life”

Mesozoic: “middle life”

Youngest Cenozoic: “recent life.” We are currently in the Cenozoic Era.

2. Era- Eons are subdivided into Eras based on the fossil record.

3. Period- Eras are subdivided into periods. Names of time periods are based on the names of

rock formations around the world.

We are currently in the Quaternary Period.

Examples: Permian period comes from the province of Perm in Russia

Pennsylvanian period comes from the US state.

Cretaceous period is Latin for “chalk.”

We are currently in the Holocene Epoch.

4. Epoch- smallest unit of time on the geologic time scale.