Plate Boundaries Flashcards
What are the 4 types of plate boundaries?
Conservative, Destructive, Constructive and Collision.
Conservative boundary
The two plates are sliding in the same direction, however one is moving faster. As the plates slides past eachother, they snag. Pressure and tension builds up as the plates lock together, and eventually they break causing a sudden surge forward.
Destructive boundary
The two plates are pushed together and the heavier oceanic crust gets subducted beneath the lighter continental crust. The oceanic plate sticks and locks as it tries to slide under.
Constructive boundary
The edges of the plates that make up the lithosphere are called boundaries or margins. New crust is mainly created at plate boundaries in mid-ocean, where the sea floor is spreading. Older crust is destroyed near the edges of oceans, where the plates collide and one dives below the other and melts.
Collision boundary
Collision happens when two continental plates crash into eachother causing earthquakes and old mountains. An example would be Everest, caused by the Eurasian plate and the Indo-Australian plate crashing into eachother.
What is a volcano?
An opening in the Earth’s surface. It is a tectonic landform created by tectonic activity. Many volcanoes occur at plate boundaries.
What is a volcanic eruption?
A volcanic eruption is the release of heat, lava ash and gas through the Earth’s crust. There are different types of eruption (not all with lots of lava)
What happens when magma reaches the Earth’s surface?
It is called lava, and when it cools, forms rock.
What boundaries do volcanic eruptions occur at?
Destructive and Constructive
Active volcano
Erupted recently, likely to erupt again
Dormant volcano
Hasnt erupted for 2000 years, but could again.
Extinct volcano
Highly unlikely to ever erupt again
Properties of a shield volcano
Wide base, gently sloping sides, basic lava, runny lava, frequent but rarely violent eruptions
Properties of a composite volcano
Violent, Steep sided, pyroclastic flows, Sticky acidic lava, made up of alternate layers of ash and lava
What plate margin are shield volcanoes found at?
Constructive
