Unit 4 - Restless Planet - Plate Tectonics Flashcards
(32 cards)
What are the 4 Layers of the Earth?
Crust
Mantle
Outer Core
Inner Core
What is the crust?
This is the thinnest layer of the Earth.
It is between 8 and 40 km thick.
It’s thinner under the oceans than it is on land.
It contains rocks and minerals.
What global patterns are described in relation to tectonic plates?
Plates and their structure, awareness of plate movements, subduction zones and their effects.
What is a subduction zone?
A region where one tectonic plate sinks beneath another.
What are the three types of plate boundaries?
- Constructive / divergent
- Destructive / convergent
- Conservative
What is the mantle?
The thickest layer of the Earth made of solid rock that can flow – Molten rock.
What causes convection currents in the mantle?
Heat source from the core.
How do convection currents affect tectonic plates?
Semi molten rock spreads out carrying the plate.
What are the two types of crust?
- Oceanic crust
- Continental crust
What is the thickness of oceanic crust?
About 5km thick.
How thick is continental crust?
Approximately 30km deep.
What is the definition of a plate boundary?
A margin between two or more plates.
What is lithosphere?
Made up of crust and upper mantle.
What happens at a destructive (convergent) plate boundary?
Two plates push against each other; the heavier plate sinks below the lighter plate.
What geological features can form at a destructive plate boundary?
- Volcanoes
- Earthquakes
What occurs at a conservative plate boundary?
Two plates slide past each other without creating or destroying land.
What is a constructive (divergent) plate boundary?
Where two plates move away from each other.
What is an earthquake?
The shaking and vibration of the Earth’s crust due to movement of the Earth’s plates.
What is the focus of an earthquake?
The point at which the rock moves and seismic waves start.
What is the epicenter of an earthquake?
The point directly above the focus on the Earth’s surface.
What causes seismic waves during an earthquake?
The sudden release of pressure when locked plates jolt into a new position.
What happens to pressure at a plate margin over time?
It builds up until it is released, causing an earthquake.
What is a destructive (collision) plate boundary?
Where two continental plates move towards one another.
What are the effects of a constructive plate boundary?
Causes volcanoes and earthquakes, forming mid-ocean ridges.