Plate Tectonics - 8th Grade
Terms in this set (45)
The theory that explains why and how continents move is called
which led to the development of plate tectonics?, Late 1800s
By what time period was there evidence supporting continental drift
and how does it move?, Asthenosphere & it flows very slowly
What is "plastic" rock
They are on top of the plates & they move
Describe how continents and oceans are carried on tectonic plates.
How many major tectonic plates have scientists identified?
Familiar outlines of the continents and oceans often do not match the outlines
Why are the boundaries of the tectonic plates not always easy to identify?
by studying data from earthquakes
How do scientists identify plate boundaries?
A sudden movement along the boundary of a tectonic plate is an
2 or more plates may meet in the area.
Frequent earthquakes in a given zone are evidence that
Some form when plate motions generate magma that erupts on Earths surface
How do volcanoes help to identify the locations of plates boundaries?
Pacific Ring of Fire
A zone of active volcanoes that encircles the Pacific Ocean is known as the
The Pacific Oceans is surrounded by plate boundaries.
What do the characteristics of the Pacific Ring of Fire indicate?
Middle of ocean basin, edges of the continents, & within countries
Name three areas where plate boundaries may be located
rises to surface & cools to form new ocean lithosphere
What happens to magma at divergent boundaries?
warm, light, & sits higher than surrounding sea floor because less dense
Describe the rock that forms when magma cools to form new oceanic lithosphere
A narrow valley that forms where the plates separate at a divergent boundary is called a
Where are most divergent boundaries located?
The Red Sea
Describe an example of a rift valley
the oceanic lithosphere is less dense than the continental lithosphere, so it sinks or, Subducts
When oceanic lithosphere collides with continental lithosphere
What deep-ocean feature forms at subduction zones?
it heats up and releases fluids into the mantle, causing magma to form and rise to the surface, forming, Oceanic lithosphere
As the oceanic plate subducts
oceanic lithosphere is denser, so it subducts, or sinks under the less dense continental lithosphere
What happens when two plates made of continental lithosphere collide?
What is an example of a large mountain range formed when two plates made of continental lithosphere collided?
One plate subducts under the other plate and makes a deep ocean trench. Fluids are released from the subducted plate causes mantle rock to melt and form magma.
What happens when two plates made of oceanic lithosphere collide?
What is produced from magma formed from melted rock?
An example of a feature that formed when two plates made of oceanic lithosphere collided is
two plates sliding past each other horizontally
What causes earthquakes at transform boundaries?
don't produce magma
How are transform boundaries different from other types of boundaries?
San Andreas Fault
An example of transform boundary is the
North America & Pacific Plates
The San Andreas Fault is located between which two plates?
Transform boundaries that connect short segments of a mid-ocan ridge are called
South American and Nazca plates at the chilean trench along the west coast of South America
What is an example of a convergent boundary?
North America & Eurasian plates at the mid-Atlantic Ridge.
What is an example of a divergent boundary in the mid-Atlantic?
The movement of heated material due to differences in density is called
denser water sinks and the warmer water rises to the surface to create a cycle is called, a convection cell
The cycle in which the cooler
Earth's core and radioactivity
Earth's mantle is heated by energy generated by
hot material in the mantle sinks
What causes tectonic plate movement?
warmer rock at a mid-ocean ridge as it cools?, It is elevated above nearby rock.
What happens to newer
sliding rock is called, Ridge Push
The force on the rest of the plate from the asthenosphere below cooling
Ridge push may help & drive plate motions
What happens as a result of ridge push?
what did scientists study for clues about forces that drive plate motion?, No. Scientists looked at convergent boundaries for other clues about forces that drive plate motion.
Is Ridge push the main driving force of plate motion? Along with ridge push
forms the asthenosphere & rises to surface
What happens to magma in places where plates pull away from each other at mid-ocean ridges?
The force exerted by a sinking plate caused by the subduction of lithosphere into the asthenosphere is called
Compared to the speed of plates that are not suducting plates that are subducting move
convection cell, ridge push and slab pull
What three mechanisms of Earth's convecting system work together to cause plate motions?