Science Unit 6

Geo

Earth

Geological Time Scale

A system that organizes the Earth's history into distinct periods.

Continental Drift

Continents move over Earth's surface.

Pangaea

Supercontinent from millions of years ago.

Alfred Wegener

Developed the theory of continental drift.

Lithosphere

The crust and uppermost layer of the mantle

Asthenosphere

Lower layer of mantle (malleable, plastic like)

Sea floor spreading

When two sides of a mountain move away from eachother and magma from earths interior wells up. Then it solidifies into rock and it is cooled by the sea, creating new ocean floor.

Mid-ocean ridge *

Mariana's Trench

The longest deep sea trench located on the floor of the western North Pacific Ocean. Formed by subduction.

Relative dating

Determines the sequence of events by comparing rock layers.

Absolute (radio metric) dating

Precision of dating by measuring radioactive decay of elements in rock.

Evidence* for continental drift

• Rock strata (layers) oldest on bottom newest on top.

• shape of continents

• fossils

• Glaciers melt and move causing hills, leaving markings

Crust

Outermost layer of earth. Crust is thin, brittle, and solid.

Continental crust

thicker and less dense

Oceanic crust

thinner and more dense

Mantle

Layer of rock between earths crust and core that flows. The mantle is the thickest layer and it is a semi-solid. Flows because of temperature differences from bottom to top.

Outer core

Second hottest part of Earth, liquid because of extreme heat and pressure.

Inner core

Made of liquid iron, nickel, sulfur, and oxygen. The inner core is a solid sphere, with intense heat, it is the hottest layer.

What do convection currents drive?

The movement of plate tectonics.

What happens in a convection current?

1) Heat from the core warms the lower portion of the mantle (asthenosphere).

2) Warm mantle material becomes less dense and rises.

3) When the warm material reaches the upper mantle, it starts to cool, becomes more dense, and sinks towards the core.

Plate tectonics

The theory that explains how Earths surface is broken into plates that move. These plates are part of the lithosphere.

What causes plates to move?

• Convection currents in the mantle.

• hot rock rises, cool rock sinks. This movement pushes and pulls plates.

Divergent plate boundaries - action

Move apart

What do divergent plates cause?

It makes new crust form. It also results in sea floor spreading, and mid-ocean ridges. Ex. Mid-Atlantic Ridge

Convergent plate boundary (general

Plates move towards eachother (collide).

Convergent (continental - continental) collision

1 plate buckles and pushes the other plate up.

Convergent Continental-Continental result

Mountains and/or volcanoes. Ex. the Himalayas.

Convergent (continental - oceanic) collision

Denser oceanic plate gets pushed under the continental plate in a process called subduction.

Convergent (continental - oceanic) result

Volcanoes, earthquakes, trenches. One example is Mariana's trench.

Convergent (oceanic - oceanic) collision*

One ocean plate gets pushed under another. Called subduction.

Convergent (oceanic - oceanic) damage

Causes volcanoes.

Transform boundary action

Plates slide past each other horizontally.

What is the place where two plates slide past each other called?

Fault

What can a transform boundary result in?

Earthquakes. Ex. San Andreas fault.

Temporal Scale

Microscopic to global in size (space affected.

Spatial scale

Fractions of a second to billions of years (time).

What evidence do scientists use to create the Geological Time Scale ?

• Analyzing Earth's rocks and fossils.

• This analysis involves relative dating and radiometric dating.

Meteors: What is it?

A bright streak of light that results when a meteoroid burns up in the Earth's atmosphere.

Meteors: How does it impact the Earth?

Large meteors can cause craters, dust clouds, and even long term climate shifts.

Meteors: On what scale?

• Quick

• Small/large

Earthquakes: What is it?

A sudden shaking of the ground caused by the movement of tectonic plates.

Earthquakes: How does it impact the Earth?

Landslides, mud flows, and changes in river flows.

Earthquakes: On what scale?

• Quick

• Small or large

Volcanoes: What is it?

A vent or fissure in the Earth through which volcanic material can pass.

Volcanoes: How does it impact the Earth?

Volcanic mountains and islands.

Volcanoes: On what scale?

• Quick

• Small or Large

Uplift: What is it?

The rising regions of the Earth's crust to higher elevations.

Uplift: How does it impact the Earth?

The raising of land or sea floor, building mountains.

Uplift: On what scale?

• slow

• small or large

Landslides: What is it?

The sudden movement of rock and soil down a slope

Landslides: How does it impact the Earth?

Landslides flatten slope, they dam rivers too.

Landslides: On what scale?

• Quick

• Small or large

Weathering: What is it? *

The process by which rock materials are broken down by the action of physical or chemical processes.

Weathering: How does it impact the Earth?

Weathering impacts the Earth by breaking down rocks and materials shaping landscapes and contributes to soil formation.

Weathering: On what scale?

• Long

• Large

Erosion: What is it?

Erosion is the process by which wind, water, ice, or gravity transport sediment from one location to another.

Erosion: How does it impact the Earth?

Erosion impacts the Earth by carving out landscapes, transporting sediments and reshaping the land.

Erosion: On what scale?

Erosion occurs over a long period of time and its effects can be small or large.

Deposition: What is it?

Deposition is the process in which material is laid down.

How does deposition impact the Earth?

Deposition impacts the Earth by building up landforms like beaches, dunes, and flood plains.

Deposition: On what scale?

Deposition occurs over a long period of time and its impact can be small or large.