Continents are thought to have moved based on their -------- ----------
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
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
Earthquake activity and volcanism are common along ----- ------
The magnetic patterns on either side of an ----- -----are mirror images of each other
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
A field with the same orientation as today's field is said to have ...
A field that is opposite to the present field has...
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
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?
tectonic plates interact at places called plate _ _ _ _ _ _ _ _ _ _
places where tectonic plates move apart are called
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 are classified according to the
type of crust involved
oceanic crust is mostly made out of...
which feature forms when 2 oceanic plates converge?
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
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
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 ____
Convection currents in the mantle are related to plate motions by r___ ___ and s___ ___