F u
The rate at which plates move apart is approximately
2 or 1.5 centimeters a year
In addition to the puzzle like fit of the continents, when evidence did weganer used to support his continental drift hypothesis
Climate data, fossil data, rock data
Wegener developed a hypothesis called Which proposed that earth's continents had once been joined as a single landmass that broke apart and sent the continents adrift
Continental drift
In the Are thought to be driving mechanism of plate movements
Convection current in mantle
Oceanic crust is more Continental crust is more
Dense and thin; buoyant and thick
The of crustal material affects how plates converge
Density
Crust is destroyed among which of the following boundaries
Divergent and transform
Earth's magnetic field results from movement in the inner core
False outer
convergent boundary occurs where two tectonic plates slide horizontally past each other
False transform
the region where two tectonic plates are moving toward each other is called a divergent boundary
False transform
Two major ocean floor features discovered by data collected by sonar and magnetometers include underwater chains, called ocean trenches and deep-sea ridges
False- ridges and trenches
Early mapmakers thought earths continents had moved based on the coastlines Like pieces of a puzzle
Fitting
mountain rages located on both sides of the Atlantic Ocean
Have the same rock types, structures and ages.
During seafloor spreading Is forced up to the crust along an ridge. The ridge spreads apart, and rising magma fills the gap and Into ocean floor. The process countnues forming new ocean floor that slowly Away from the ridge
Magma, ocean, hardens, moves away
A happens when the flow in the outer core changes, and earth's magnetic field changes direction
Magnetic rosol
What is the source of thermal energy for convection in earth's mantle
Radioactive decay
What features are associated with divergent boundaries
Rift valleys and ocean ridges
theory that explain how new oceanic crust is formed at ocean ridges, slowly moves away from ocean ridges, and is destroyed at deep - sea trenches
Seafloor spreading
Technologies that changed perceptions of the ocean floor include Which measure the water depth and maps the ocean floor, and the Which records the magnetic field generated by ocean floor rocks
Sonar, megnator
are huge pieces of crust and rigid upper mantle that fit together at their edges to cover earths surface
Tectonic plates
What rock evidence led to the discovery of seafloor spreading?
The age of ocean crust the oldest oceanic rocks the thickness of ocean
what did scientists learn by matching magnetic patterns on the seafloor with know patterns of magnetic reversals on land
The age of the ocean floor
How does glacial deposits supports the hypothesis of continental drift
They have been found in places with warm climates
A rift valley is a long, narrow depression that forms when continental crust begins to separate
True
Continental drift was rejected in part because wegener proposed that earth's rotation caused continents to move
True
Pangea is the ancient landmass made up of all the continents that begin to break apart about 200million years ago
True
The imaginary line on a map that shows points that have the same age is called an isochron
True
The magnetic pattern of ocean floor rocks on one side of an ocean ridges is a mirror image of that of the other side
True
The study of the history of the earths magnetic field is called paleomagnetism
True
scientist do not fully understand the forces that cause tectonic plates to move.
True
Before they could make seafloor map, scientists through the topography of the seafloor
Was completely flat
Something yet not answered
What force causes tectonic plates to move
Subduction occurs where the ocean crust bends down towards the mantle at a
deep sea trench
what process occurs when two plates collide and the denser plate eventually descends below the other, less dense plate
subduction
