Plate Tectonics
What is the theory that explains how Earth's lithosphere is divided into large, rigid plates that move across the Earth’s surface?
Plate Tectonics
What type of boundary is created when two tectonic plates move away from each other?
divergent
What is the term used to describe the motion of tectonic plates carrying continents and oceans?
plate motion, or tectonic shift
How does the theory of plate tectonics explain the formation of mountain ranges like the Himalayas?
Two continents collide
Oceanic crust is relatively thin compared to continental crust. In places, continental crust is thick enough to form land masses higher than Earth's seas and oceans.
The Earth’s lithosphere is broken into how many MAJOR tectonic plates?
here are seven major plates: African, Antarctic, Eurasian, Indo-Australian, North American, Pacific and South American
At what type of boundary do earthquakes most commonly occur?
transform
How does the process of seafloor spreading contribute to the movement of tectonic plates?
Mid-Ocean Ridges. Convection currents drive the movement of Earth's rigid tectonic plates in the planet's fluid molten mantle.
Describe how rift valleys are formed within the context of plate tectonics.
the process of seafloor spreading
divergent
Why is oceanic crust denser than continental crust?
Continental crust is made largely of granite, while oceanic crust is mostly composed of basalt. Basalt contains a higher proportion of heavier elements like iron and magnesium, making oceanic crust denser than continental crust
Name the layer of the Earth beneath the lithosphere that is responsible for the movement of tectonic plates.
the asthenosphere!
What happens when two tectonic plates slide past each other horizontally?
a transform plate boundary. As the plates rub against each other, huge stresses can cause portions of the rock to break, resulting in earthquakes
What type of force causes tectonic plates to move?
thermal convection
What geological evidence supports the theory of plate tectonics?
Earthquakes, mountain building and volcanic activity
How do the compositions of continental and oceanic crust differ?
Continental crust is thicker but less dense than oceanic crust.
How are mountains and volcanoes often formed in the context of plate tectonics?
convergent plate boundaries
Describe the features that are commonly associated with a convergent plate boundary.
Deep ocean trenches, volcanoes or non-volcanoes mountains, island arcs, submarine mountain ranges, and fault lines
How does the movement of tectonic plates affect Earth's surface over long periods of time?
Erosion and subsidence (sinking of the earth's crust) eventually causes older islands to sink below sea level.
How do scientists believe the Hawaiian Islands were formed in relation to plate tectonics?
The Hawaiian Islands were formed by such a hot spot occurring in the middle of the Pacific Plate.
The main reason that oceanic crust does not get to be as old is due to density - tectonic plates mainly formed of oceanic crust are heavier, and so sink beneath continental crust at subduction boundaries, where it melts as it sinks, and gets recycled into the mantle.
Define subduction in the context of plate tectonics.
Subduction occurs when an oceanic plate runs into a continental plate and slides beneath it.
Explain what occurs at a transform plate boundary
As the plates rub against each other, huge stresses can cause portions of the rock to break, resulting in earthquakes.
Provide an example of a natural feature that demonstrates the movement of tectonic plates.
Deep ocean trenches, volcanoes, island arcs, submarine mountain ranges, and fault lines
Himalaya Mountains
Mid-Atlantic Ridge
Explain the process of seafloor spreading and its significance in plate tectonics.
Seafloor spreading occurs at divergent plate boundaries. As tectonic plates slowly move away from each other, heat from the mantle's convection currents makes the crust more plastic and less dense
Deep ocean trenches, volcanoes, island arcs, submarine mountain ranges, and fault lines are examples of features that can form along plate tectonic boundaries. Volcanoes are one kind of feature that forms along convergent plate boundaries, where two tectonic plates collide and one moves beneath the other.