Earth Processes and Rock Layers. Mountain Building Mountain building occurs when 2 continental plates of equal densities collide. – The plates crush together,

Earth Processes and Rock Layers

Mountain Building

• Mountain building occurs when 2 continental plates of equal densities collide.– The plates crush together,

causing land to be pushed up and break.

• Mountain building changes the shape of Earth’s surface.

Erosion• Erosion is the wearing away

of material through wind and water.

• The process of erosion can expose (uncover) layers of rock.

Mountains and Erosion

• Over time all mountains will crumble through erosion.

• Mountain peaks will eventually become rounded hills.

Glaciers • Glaciers are slow moving masses of

ice formed from compacted layers of snow.

• Glaciers move and change with temperature change, gravity, and high pressure.

• Glaciers carve out mountains.

• Glaciers move rocks out of mountains.

Changes to Earth’s Surface

• Erosion, mountain building, and glacier movement change the surface of the Earth and earth materials to form layers.

• Rock layers are used to show the geologic time and history of the Earth.

Rocks and Geologic Time

•The observation and study of rock layers is used for the measurement of geologic time.

•The earth has distinct layers of rock–The rock layers show a progression of

organisms from layer to layer

Principle of Superposition

•Principle of Superposition– The oldest layer is on the bottom, then

each layer up is younger, with the youngest layer being on the top – This is because sediment is deposited on top of

previously existing sediment.

Relative Dating

•Relative dating can be used to estimate the order of prehistoric and geologic events

•This happens by observing where fossils are found in layers of rock –The oldest rock layers contain the oldest fossils and

the youngest rock layers contain the youngest fossils–A fossil must have existed at the time when the rock layer

was formed, which is how we can tell

Relative Dating

Relative Dating