Unit Four - Plate Boundaries Flashcards
How does the mid - ocean ridges and rift valleys work?
The mid - atlantic ridge is high because hot mantle rocks are rising below it, pushing the earth’s crust up. As those rocks get closer to the surface, they melt, and the resulting magma continues on an upward journey, some of it eventually erupting onto the floor of the central rift valley.
Mid-ocean ridges occur along divergent plate boundaries, where new ocean floor is created as the Earth’s tectonic plates spread apart. As the plates separate, molten rock rises to the seafloor, producing enormous volcanic eruptions of basalt.
What is the Convergent Plate Boundary?
Plates move towards each other
What is the Transform Plate Boundary?
Plates slide horizontally past one another.
What is a mid - ocean ridge?
Like an underwater mountain, the ridge is found in the center of the ocean, where the sea - floor spreading starts to take place. The closer a piece of the rock is to the ridge, the younger it is.
What happens as a result of transform plates?
This creates earthquakes, faults and the dislocation of rocks.
What is the theory of plate tectonics?
The theory of plate tectonics explains how the “solid” lithosphere consists of a series of plates that float on the partially molten section of the mantle.
What happens as a result of convergent plates?
It creates mountains, earthquakes, volcanic activity and trenches.
What happens as a result of divergent plates?
This creates new oceanic crust, volcanic activity, shallow earthquakes, ocean ridges, deep rift valleys and convergent plates.
How do different plate boundaries interact and help form a volcano?
Due to diverging plates and magnetic orientation, the oceanic crust moves towards a continental crust. Since the oceanic crust is more dense thanthe continental crust, it bends down and subducts. This creates a mountain. When the oceanic crust bends down, it eventually reaches the asthenosphere and melts into magma. The gases rises up from the magma and wants to escape. When the gases and pressure builds up in the mountain, the mountain explodes and lava seeps out, creating a volcano.
What crust is more dense?
Oceanic crust is more dense than the continental crust (at 3.0), so it sinks underwater and tends moves under the continental crust
What is the Divergent Plate Boundary?
Plates move away from each other.
What is a rift valley?
As a result of sea - floor spreading, a rift valley is an enormous fracture in the sea floor that progressivly widens.
