Earth Science

What is the Continental Drift Theory?

The theory that continents are separating by drifting across the oceans.

What does the Theory of Plate Tectonics state?

The theory that the Earth’s crust is broken into many large pieces (plates) that move on the mantle.

What is Seafloor Spreading?

The process of new crust forming at ocean ridges and spreading outwards, caused by divergent plate boundaries.

What is Subduction?

Where one crust sinks beneath another crust, caused by converging plate boundaries.

What are the characteristics of Continental Crust?

The crust that forms the continents, thicker but less dense than oceanic crust.

How does Oceanic Crust differ from Continental Crust?

Oceanic crust is thinner and denser than continental crust; it forms the ocean floor.

What is a Converging Boundary?

Where plates are moving towards each other, causing crust to be melted into the mantle and referred to as destructive boundaries.

Define a Diverging Boundary.

Where plates are moving apart from each other, allowing magma to rise and form new crust, called constructive boundaries.

What happens at a Transform Boundary?

Plates slide parallel to each other in opposite directions; no crust is created or lost, known as conservative boundaries.

What occurs during an Earthquake?

The rapid movement of the ground due to the movement of the Earth’s crust.

What is an Epicenter?

The point on the Earth’s surface directly above the focus of an earthquake.

Where is the Focus of an earthquake located?

It is the place below the ground where the earthquake starts.

What are Hot Spots in geology?

Isolated areas away from plate boundaries where a lot of hot magma is created.

What is the function of a Seismometer?

An instrument that detects seismic waves from earthquakes to measure their intensity.

Describe a Volcano.

A natural opening in the Earth’s crust connected to molten rock (magma) deep inside.

Define a Volcanic Eruption.

An event that causes lava to flow from vents and expels rock fragments, dust, ash and gases from the volcano's crater.

What is the Crust?

The outermost layer of the earth, including landforms, rock and soil, varying in thickness from 5km to 70km.

What is the Mantle composed of?

Located beneath the crust, made up of molten rock with temperatures between 500°C and 2000°C and approximately 2900km thick.

What was Pangea?

The former ‘supercontinent’ that included all of Earth's landmasses before they broke apart.

What is Laurasia?

The supercontinent of the Northern Hemisphere.

Define Gondwana.

The supercontinent of the Southern Hemisphere.

What is a Fault Line?

A break in a rock structure causing the sliding movement of rocks along the break.

What are Aftershocks?

Smaller earthquakes following the main shock of an earthquake.

How does the Earth's core remain solid despite high temperatures?

The iron in the Earth’s core is under immense pressure from layers above it, keeping it solid despite high temperatures.

What evidence supports the Theory of Plate Tectonics?

Shape of continents, satellite data indicating movement, and fossils of the same species found on different continents.

Who proposed the Continental Drift theory?

Alfred Wegener proposed the Continental Drift theory.

How did flightless bird fossils end up on different continents?

Flightless bird fossils found on different continents are evidence that all continents were once connected as Pangea.

What causes deep ocean trenches near land?

Deep ocean trenches are formed by the subduction of oceanic crust beneath less dense continental crust at converging boundaries.

Why does Australia have few earthquakes?

Australia is not located close to any plate boundaries where tectonic activity occurs.

What factors can influence the devastation caused by an earthquake?

Proximity of the epicenter to the focus, population density, building stability, earthquake magnitude, and access to emergency services.

What is a Seismologist?

A scientist who studies earthquakes.

Explain the Richter Scale.

A scale that measures the magnitude of an earthquake, where an increase of 1 indicates a 30 times increase in energy.

Why are volcanoes often found near subduction zones?

Volcanoes are formed at subduction zones because oceanic crust sinks and melts into magma, creating pressure that leads to eruptions.

Differentiate between active, dormant, and extinct volcanoes.

Active volcanoes are currently erupting or have erupted recently; dormant volcanoes have not erupted in over 20 years but could still erupt; extinct volcanoes have not erupted for thousands of years and are unlikely to erupt again.