Dynamic Crust Flashcards
What is plate tectonics?
the theory that the earth’s crust is composed of about a dozen “puzzle pieces” called plates. These plates shift, causing crustal changes such as volcanoes, earthquakes and mountains building along the edges of the plates.
How are plate tectonics driven?
by convection currents in the upper mantle. Hotter material moves upward causing divergent plate boundaries.
Convergent boundaries occur at side of plate opposite the divergent boundary
True or False:
The continental crust is granite, less dense and thicker than the ocean crust
TRUE!!
the oceanic crust is basalt, more dense (that’s why it’s UNDER the water) and thinner
the continental crust is thicker (think MOUNTAINS)
Describe what the lithosphere is.
the rigid, outermost layer of the Earth’s rocks and minerals, which consists of the crust and upper mantle.
The crust is broken up into lithospheric plates.
Describe what is happening at plate boundaries and why.
tectonic plates are either colliding (convergent), pulling apart (divergent), or sliding past each other (transform), causing geological events like earthquakes, volcanic eruptions, and mountain formation due to the immense forces created by the movement of these plates driven by convection currents within the Earth’s mantle;
essentially, the Earth’s crust is constantly shifting and interacting at these boundaries, leading to various geological features depending on the type of movement involved
Describe the inferred properties of the Earth’s interior.
And explain how scientists came up with that information.
Based on analysis of seismic waves, the Earth’s interior is inferred to be composed of distinct layers with increasing density towards the center, including a thin solid crust, a mostly solid mantle with a partially molten asthenosphere, a liquid outer core, and a solid inner core, with the composition of the core being primarily iron and nickel, generating the Earth’s magnetic field due to its liquid state; the properties of each layer are inferred from the behavior of seismic waves as they travel through the Earth.
What is meant by continental drift?
the idea that Earth’s continents continually undergo large-scale horizontal movements
What is happening at CONVERGENT boundaries?
At a convergent boundary in earth science, two tectonic plates are colliding with each other, often resulting in one plate sliding beneath the other in a process called subduction, which can lead to the formation of volcanoes, earthquakes, deep ocean trenches, and mountain ranges depending on the type of plates involved; essentially, it’s where crust is destroyed as plates move towards each other and collide.
What are the three types of convergent boundaries?
1-Oceanic-continental:
An oceanic plate subducts beneath a continental plate, creating a volcanic arc along the continental margin.
2- Oceanic-oceanic:
One oceanic plate subducts beneath another, forming a chain of volcanic islands (island arc).
3- Continental-continental:
Two continental plates collide, leading to the formation of a large mountain range
What is happening at DIVERGENT boundaries?
At a divergent boundary in Earth science, two tectonic plates are moving apart from each other, causing magma from the Earth’s mantle to rise up and solidify, creating new oceanic crust along the boundary, often referred to as a “spreading center”; this process is known as seafloor spreading.
What is an example of a DIVERGENT boundary?
The Mid-Atlantic Ridge: A major undersea mountain range where the North American and Eurasian plates are pulling apart.
The East African Rift Valley: A large continental rift zone where the African plate is splitting apart.
The Red Sea: A narrow body of water where the Arabian plate is moving away from the African plate.
Describe what is happening at TRANSFORM boundaries.
two tectonic plates slide past each other horizontally, causing earthquakes along the fault line where they meet, with no new crust being created or destroyed at the boundary; essentially, the plates are grinding against one another as they move in opposite directions, creating a zone of shearing and deformation along the fault line;
What is an example of TRANSFORM boundary?
San Andreas Fault in California where the Pacific Plate slides past the North American Plate.
What is an example of CONVERGENT boundary?
Andes Mountains
Himalayan Mountains
What forms at CONVERGENT boundaries?
Key points about convergent boundaries:
Subduction:
When an oceanic plate meets a continental plate, the denser oceanic plate usually subducts (sinks) beneath the continental plate, creating a deep ocean trench at the boundary.
Volcanic activity:
As the subducting plate melts, magma rises to the surface, forming a chain of volcanoes parallel to the plate boundary.
Mountain building:
When two continental plates collide, neither plate can subduct easily, leading to the crumpling and uplift of the crust, forming large mountain ranges like the Himalayas.
Earthquakes:
Convergent boundaries are major earthquake zones due to the friction and stress caused by the colliding plates.
