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Continents are thought to have moved based on their -------- ----------

Matching coastlines

The super continent made up of all of earths continents


Alfred Wegener did NOT use -------- ----- -------- to support his hypothesis of continental drift

Magnetic field data

What are 3 pieces of evidence did Wegener use to support his idea of continental drift ?

1. Ancient climate evidence 2. Data on ancient reptiles and ferns 3. Evidence from rock formations

Fossil evidence that supported wegener's idea of continental drift included...

Land dwelling animals

Fossils of aquatic reptiles found in freshwater Rocks Suggested to Wegener that these reptiles...

Did not cross the oceans

Based on observations of fossils of Glossopteris, Wegener concluded that...

Continental rocks containing these fossils had once been joined

Coal beds in Antarctica indicated to Wegener that these continent was ...

Once located closer to the equator

Based on the glacial deposits he observed Wegener argued that

Landmasses drifted away from the South Pole

Most scientists rejected wegeners hypothesis of continental dress because he

Couldn't explain how or why the continents moved

----- uses soundwaves to measure Water depth


Maps made from ----- and ------------data led to the discovery of ocean ridges and deep-sea trenches

Sonar and magnetometer

----- ------ are vast underwater mountain chains

Ocean ridges

Rock samples taken near ocean ridges are --------than rock samples taken your deep-sea trenches


The thickness of ocean floor sediments --------- with distance from an ocean ridge


How old are the oldest ocean Floor rocks

180 million years

The study of magnetic record preserved in earths rocks


A change in Earth's magnetic field

Magnetic reversal

Earthquake activity and volcanism are common along ----- ------

Ocean ridges

The magnetic patterns on either side of an ----- -----are mirror images of each other

Ocean ridge

The theory states that Ocean-crust is formed at Ocean ridges and is destroyed at deep-sea trenches

Sea floor spreading

A new sea floor, as it's carried away from ocean rides, ____ & _____ and becomes more _____ than the material beneath it

cools contracts dense

-------- --------- explains that Earths continents move because they ride atop ocean crust as it moves away from ocean ridges

Sea floor spreading

Fill in sequence w/ 1 2 3
_ magma fills gap that's created
_magma hardens to form new ocean crust
_magma is forced up toward crust

2 3 1

Earths -------- ----- has changed over time

Magnetic field

A field with the same orientation as today's field is said to have ...

Normal polarity

A field that is opposite to the present field has...

Reverses polarity

Device used to measure the ocean floors magnetic field


When the ocean floor's magnetic readings match the present, the 2 fields -------


This produces a -------- than normal reading


When the magnetic readings of the ocean floor are reversed, compared to today's field, the two fields partially -----


The 2 fields cancel to produce a ----- than normal reading


Magnetic data of the ocean floor has been used to generate --------- maps


Isochron maps show that the ocean floor is ------- near ocean ridges and ----- deep see trenches

Younger older

Device that can detect small changes and magnetic fields


Minerals containing this act like small compass needles and record the orientation of Earth's magnetic field at the time of their formation


Was constructed from data gathered from continental basalt flows

Geomagnetic time scale

This type of line connects points on a map that have the same age

New ocean crust

Each cycle of spreading and magma intrusion along an ocean ridge results in the formation of this


which theory states that earth's crust and rigid upper mantle move in different directions and at different rates over earth's surface?

plate tectonics

tectonic plates interact at places called plate _ _ _ _ _ _ _ _ _ _


places where tectonic plates move apart are called

divergent boundaries

where are most divergent boundaries found?

on the seafloor

what happens along a divergent boundary

new crusts form

the mid atlantic ridge is an example of

a divergent boundary

places where tectonic plates come together are called

convergent boundaries

convergent boundaries are classified according to the

type of crust involved

oceanic crust is mostly made out of...


which feature forms when 2 oceanic plates converge?

subduction zone

what do subduction zones usually include

trenches and volcanoes

when two oceanic plates converge and one is subducted into the mantle, the melted ----- erupts and forms an --- of -------

magma arc islands

Which of the following landforms results from divergence of continental crust

Rift valley

when oceanic plate converges with a continental plate a ____ and a _____ ___ with ______ form

trench mountain range volcanoes

What feature is associated with a continental continental plate boundary

A mountain range

At which tectonic plate boundary do plates slide horizontally passed each other

Transform boundary

What is not associated with transform boundaries


In the process of convection magma ____ because it is less ____ and the ___ matter goes ____ when it reached the surface it hits against making the surface _____ then the magma ____ so it's density _____ so it goes back down

Rises dense cool down separate cools increases

Convection currents form when the currents _____ decreases so it gets hotter and ____

Density rises

Convection currents in the mantle are related to plate motions by r___ ___ and s___ ___

Ridge push slab pull

Ridge push is when plates ____ ____

Come apart

Slab pull is when plates ____ _____

Come together

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