Henricksen-Geologic Time Scale

Geologist

A scientist who studies the Earth’s crust and it’s history.

Paleontologist

A scientist who studies fossil remains

Law of Superposition

Says the newest rock layers are found at the top of a rock sequence

Relative Age

Determines the relative order of past events, but not exact

Disturbed

When rock layers are shifted by forces

Index Fossils

Special fossils used to identify and date rock layers

Age

If 2 rock strata in different places contain the same index fossils, they are likely the same age.

Absolute Dating

The most accurate form of dating rocks and fossils. Also called radiometric dating.

Half-life

The predictable time an element takes to decay

Precambrian

About 88% of Earth’s history falls within the Precambrian era.

Geologic Time Scale

Broken into time chunks from largest to smallest : Eon, Era, Period, Epoch

Zircon

The oldest mineral found on Earth and was found in Australia. Around 4.4 billion years old

Pangaea

Super continent during the Paleozoic Era

Mesozoic Era

Dinosaurs, birds, and flowering plants first appeared

Cenozoic Era

Era we currently live in. The epoch is Holocene

How many mass extinctions have there been?

5

Cretaceous-Tertiary

Name of the most recent mass extinction about 65 million years ago

Meteor

Meteor strike is believed to have wiped out the dinosaurs