Plate Tectonics

Question 1

Layers of the Earth

Answer 1

The Earth is composed of three main layers: crust, mantle, and core. Each layer varies in composition, temperature, and density

Question 2

Crust

Answer 2

The outermost layer of the Earth. The two types are: Oceanic Crust: Thin (~3-5 miles), dense, and primarily basalt. Continental Crust: Thicker (~25 miles), less dense, and primarily granite

Question 3

Lithosphere

Answer 3

Rigid outer layer of the Earth, including the crust and uppermost mantle. It is broken into tectonic plates

Question 4

Asthenosphere

Answer 4

A semi-molten, ductile region of the mantle beneath the lithosphere. Convection currents in this layer drive plate movements

Question 5

Theory of Plate Tectonics

Answer 5

The idea that Earth’s lithosphere is divided into tectonic plates that move due to convection currents in the mantle. This explains earthquakes, volcanoes, and mountain formation

Question 6

Plates

Answer 6

Massive, rigid sections of the lithosphere that float on the semi-fluid asthenosphere. They move and interact at plate boundaries

Question 7

Plate Boundaries

Answer 7

The regions where tectonic plates interact. There are three main types

Question 8

Divergent Boundaries

Answer 8

Plates move apart, creating new crust. associated landforms: Mid-ocean ridges (e.g., Mid-Atlantic Ridge), Rift valleys (e.g., East African Rift), Linear lakes (formed by stretching fo the crust)

Question 9

Convergent Boundaries

Answer 9

Plates collide, leading to subduction or mountain formation

Question 10

Ocean-to-Continent Convergence

Answer 10

The denser oceanic plate subducts beneath the continental plate, forming volcanic arcs and deep trenches (e.g., Andes Mountains, Cascadia Subduction Zone)

Question 11

Oceanic-to-Oceanic Plate Boundary

Answer 11

One oceanic plate subducts under another, forming volcanic island arcs and trenches (e.g., Japan, Mariana Trench)

Question 12

Continental-to-Continental Convergence

Answer 12

Both plates are buoyant, causing mountain building instead of subduction (e.g., Himalayas, Alps)

Question 13

Subduction

Answer 13

The process in which one tectonic plate moves beneath another into the mantle. This occurs at subduction zones

Question 14

Subduction Zones

Answer 14

Regions where one plate sinks beneath another. Often associated with volcanic activity, deep-sea trenches, and earthquakes

Question 15

Transform Boundaries

Answer 15

Plates slide horizontally past each other. They neither create nor destroy crust. San Andreas Fault (California): A well-known transform fault. North Anatolian Fault (Turkey): Another major transform fault system

Question 16

Intraplate Activity

Answer 16

Geological activity occurring within a tectonic plate rather than at its boundaries. Often related to hotspots

Question 17

Hotspot

Answer 17

A region where magma from deep within the mantle melts through the crust, creating volcanic activity (e.g., Hawaiian Islands, Yellowstone)

Question 18

Seismic Waves

Answer 18

Vibrations produced by earthquakes that travel through Earth’s interior. There are two main types

Question 19

Primary Waves (P-waves)

Answer 19

Fastest seismic waves. Travel through solids, liquids, and gases by compressing and expanding material

Question 20

Secondary Waves (S-waves)

Answer 20

Slower waves. Travel only through solids by moving material perpendicular to their direction of travel

Question 21

Paleomagnetism

Answer 21

The study of Earth’s past magnetic field recorded in rocks. Provides evidence for seafloor spreading and continental drift

Question 22

Seafloor Spreading Hypothesis

Answer 22

Proposed by Harry Hess, this theory states that new oceanic crust is created at mid-ocean ridges and spreads outward. Magnetic stripes on the seafloor support this idea

Question 23

Alfred Wegener

Answer 23

Proposed the Theory of Continental Drift, suggesting that continents were once part of a supercontinent called Pangea and have since drifted apart