U5 Notes + Earths Interior Diagram Flashcards
what does the theory of tectonic plates explain?
it explains the formation and location of Earths major landforms
what does tectonic mean?
comes from the greek word for mason
what is convection?
when heat is carried or transferred from hotter areas to cooler areas by the movement of fluids or gas
Where did the idea of plate movements come from?
Alfred Wegner started it in 1915 with his theory of Continental drift
How many major lithospheric plates are there?
- African
- Antarctic
- Eurasian
- Indo-Australian
- Pacific
- North American
- South American
what are Plate Boundaries?
The places where lithospheric plates touch
What are the three types of plate boundaries?
- Divergent
- Convergent
- Transform
What is a divergent boundary?
The place where to plates move away from each other
What landforms are created by a divergent boundary?
- A mid-ocean ridge ( an underwater mountain chain)
- A rift valley with sets of parallel ridges and valleys to either side
What is a ridge push?
the shoving force created as new lithosphere constantly fills in the gap between two diverging plates, this force helps push each plate away from its source
what is a convergent boundary?
the place where two plates come together and slowly smash into each other
What landforms are created by a convergent boundary?
- a deep ocean trench & an arc of volcanic islands
- a deep ocean trench & an arc of continental volcanoes
- a continental mountain range & a high plateau
What is subduction?
when old, cold, and dense oceanic lithosphere converges with another plate and slides under it
Why does subduction happen?
When two plates converge the older plate sinks back down into the asthenosphere while the younger plate floats to the top
what is slab-pull?
the tugging force created by gravity as the leading edge of the plate subducts, this force helps drag the entire plate away from its source
What is a transform boundary?
the place where two plates slide horizontally past one another
What landforms are created by a transform boundary?
Visible cracks and faults
What is a hotspot?
A localized source of high heat energy within the mantle from which hot plumes of molten material rise upwards to form volcanoes
What landforms do hotspots create?
it depends
- when oceanic lithosphere slides over a hotspot, a chain of progressively older volcanic islands is created
- when continental lithosphere slides over a hotspot, a chain of progressively older volcanic calderas is created
What is some evidence supporting the theory of plate tectonics?
- The location of landforms ( such as volcanoes, calderas, mountains, faults, rift valleys, mid-ocean ridges, and ocean trenches) along past and present plate boundaries
- the pattern of earthquakes along active plate boundaries
- Real-time data from satellite systems ( such as GPS) that measure and track plate movements
- The discovery of identical or similar fossils in rock now separated by vast distances
- The complementary shape of continental margins now separated by vast distances
- Drilling samples that measure how seafloor basalts on both sides of a mid-ocean ridge gets progressively older the further away they are from the ridge
What forces drive plate motion?
- Convection currents within Earth’s asthenosphere
- Ridge push ( due to the constant creation of new lithosphere at divergent boundaries)
- Slab pull ( due to the subduction and recycling of old lithospheric at convergent boundaries)
What are the mechanical layers of earth? ( from the inside out)
- Inner core (solid)
- Outer core (liquid)
- Mesosphere (stiff plastic)
- Asthenosphere (soft plastic)
- Lithosphere (brittle rock)
What tempeture is the inner core?
Around 10,000º F
What is the density of the inner core?
12.9 g
What is the density of the Outer core?
11 g
What is the density of the mesosphere?
5g
What is the density of the Asthenosphere?
2.5g
What is the pressure of the inner core?
3.6 Million atm
What is the pressure of the crust?
1 atm
What is the distance from the crust to the earths core?
Around 4,000 miles
What are the compositional layers? (from the inside out)
- core ( Fe, Ni)
- mantle
3.Crust
