Geologic Time Mini Unit

Law of Superposition

• The oldest layer is at the top and the youngest layer is at the bottom.

• The layers are arranged randomly without any specific order.

• In an undisturbed sequence of sedimentary rock layers, the oldest layer is at the bottom and the youngest layer is on top.

• The layers are formed simultaneously without any chronological order.

Eons

• The smallest unit of time (seconds).

• A unit of time equal to millions of years.

• The largest unit of time (billions of years).

• A unit of time used in astronomy (light years).

Epoch

• A subdivision of a period (lasting millions to thousands of years)

• A geological time frame lasting less than a million years

• A significant event in Earth's history

• A type of rock formation

Eras

• Subdivisions of eons, lasting hundreds of millions of years.

• Short periods of geological time, lasting thousands of years.

• Major divisions of the Earth's history, lasting billions of years.

• Periods of time marked by significant climatic changes.

Periods

• Subdivisions of eras (millions of years)

• Units of geological time (thousands of years)

• Types of rock formations

• Stages of biological evolution

Unconformity

• Gap in the rock record

• Continuous sediment deposition

• Formation of igneous rocks

• Presence of fossils

Fault

• A break in rock layers, usually where earthquakes may happen.

• A type of rock formation that is resistant to erosion.

• A geological feature formed by volcanic activity.

• A layer of sedimentary rock that contains fossils.

Strata

• Layers of rock

• Types of minerals

• Fossilized remains

• Sedimentary processes

Outcrop

• Exposed rock at the surface

• A type of sedimentary layer

• A geological fault line

• A mineral deposit underground

Relative Dating

• Method of determining the age of rocks by comparing them with those in other layers.

• A technique used to date fossils based on their location in sedimentary layers.

• A process of determining the exact age of rocks using radiometric methods.

• A method of dating rocks by measuring the decay of isotopes.