AICE Marine Science 2.1 Tectonic Plates Notes & Readings

crust, mantle, core

What are the Earth's layers

core

a hot sphere of dense elements (iron + nickel)

inner core and outer core

What does the core contain?

inner core

solid inner sphere

outer core

liquid outer layer that covers the inner core

mantle

a layer of hot, semisolid rock capable of very slow movement over geological timescales, that surrounds the core

mantle

earth's thickest layer

high temperature

why is the uppermost portion of the mantle highly viscous?

crust

outermost layer, layer we are most familiar with, and made of solid rocks

oceanic crust

the thinnest crust is the _____

primarily basaltic rocks filled with iron + magnesium

what is the oceanic crust made of?

continental crust

the thickest crust is the _____

granite and similar rocks

what is the continental crust made of?

oceanic crust

Which crust is denser? Oceanic crust or Continental crust?

Alfred Wegener

Who made the theory of plate tectonics?

german scientist

Who is Alfred Wegener?

continents were together as a single landmass known as pangea

The Theory of the Continental Drift says ___

continents in a single landmass

What is a pangea?

it began to move apart

What happened to the pangea?

they looked like jigsaw pieces

What did Wegener realize about the continents?

fit of coastlines, fossils distribution, and geological matches

What was the evidence for plate tectonics?

south america and africa

Where did Wegener find a fit of coastlines?

fossilized plants and animals were found on the coast of different continents separated by oceans

Describe the fossil distribution

Appalachian mountains and the mountains in West Highlands of Scotland

What were the geological matches?

south america, africa, north america, and europe

What 2 geological matches of coastlines did Wegener make?

False

True or False: Wegener received great support for his theory

it did not suggest a logical mechanism

Why did other scientists not accept Wegener's theory?

scientist who supported the theory

Who were the 'Drifters'?

scientists who opposed the theory

Who were the 'Fixists'?

they included a logical mechanism and suggest the lithosphere has sections (tectonic plates)

How did they revise the theory?

the data is used to create a clear and predictable map of where the tectonic plates were separated

How do we use SONAR?

evidence enabled them to study magnetism on the ocean floor using magnetism

How did more evidence of seafloor spreading help scientists?

the ocean's floor magnetic field is laid out in alternating stripes of normal polarity and reversed polarity

What did scientists discover using magnetometers?

igneous rock

What type of rock is a Basaltic rock?

a rock that forms from the cooling and hardening of magma

What is an igneous rock?

naturally magnetic iron called magnetite

What does an igneous rock contain?

the particles align with the magnetic field

What happens once magma reaches the Earth's surface?

magma hardens and locks particle in place, holding information about the Earth's magnetic field

What happens after the magnetite's particles align with the magnetic field?

false

True or False: The Earth's magnetic field does not reverse on average every 250,000 years, magnetic north -> magnetic south

the mantle is moving

Tectonic plates can only move if _____

convection currents

What causes the mantle to move?

molten rock of the mantle moves

How do convection currents happen?

True

True or False: Plates float and move slowly in relation to each other.

convergent, divergent, transform

What are the 3 types of plate boundaries create when plates float and move slowly in relation to each other?

->

Using arrows, explain how convergent boundaries move.

Using arrows, explain how divergent boundaries move.

slide past each other (antiparallel)

How do transform boundaries move?

wherever there is an opening in the crust

Where do volcanoes form?

True

True or False: Most volcanic activity is submarine

it forms new seafloor and gives rise to mid-ocean ridges

How do volcanoes help seafloor and mid-ocean ridges?

a sudden release of energy in the crust, seismic waves

What are earthquakes?

convergent boundaries

What boundary causes earthquakes?

2 plates cannot slip past each other and may lock together, creating tension

How do earthquakes occur?

earthquake

Released tension = _______

a long wavelength produced by the sudden movement of a lot of water

What are tsunamis?

convergent boundaries

What boundary do tsunamis have?

fast wave

Deep water = ____

the coast makes the tsunami a slow destructive wave

How does the coast affect Tsunamis?

underwater mountain ranges

What are mid-ocean ridges?

formed by the upward movement and spread out of magma

How are mid-ocean ridges formed?

in the deep ocean near mid-ocean ridges

Where do hydrothermal vents occur?

seawater seeps into the cracks of the ocean floor and is released by the magma

How are hydrothermal vents formed?

discovered in 1977, Galapagos Rift

When and where were hydrothermal vents discovered?

flat areas of ocean floor

What are abyssal plains?

in between ocean trenches and continental rises

Where are abyssal plains?

formed by the upward movement of molten material

How are abyssal plains formed?