Chapter 5- Earth's Layers
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What are the 3 main layers of earth?
Crust, mantle, core
How can we explore inside Earth?
Using rock samples or using seismic waves
What is the crust?
Outer skin of earth, consists of oceanic and continental crust
What is the mantle?
Hot but solid rock under the crust, consists of lithosphere (also in crust), asthenosphere, and lower mantle
What is the core?
Innermost layer of earth, consists of outer core (liquid), and inner core (hot solid), movements in outer core produce earth’s magnetic field
What are the types of heat transfer?
Radiation: heat through space Conduction: heat through two objects touching Convention: heat through a fluid
What are convection currents?
The flow that transfers heat within a fluid in a cycle
Where are there convection currents in the earth?
In the mantle, powered by the core
What is continental drift?
The theory of Alfred Wegener that all the continents were once joined together in one single landmass called Pangaea, and have since drifted apart
Where can we find evidence of continental drift?
From land features that line up, fossils found in different places, and climate similarities
Why was Wegener’s hypothesis rejected?
He couldn’t explain the force that pushed the continents apart, but we know now that the force was convection currents
What are mid-ocean ridges?
A chain of mountains underwater where new ocean floor is produced
What is sea-floor spreading?
When new crust is added at mid-ocean ridges because of divergent plate boundaries
What are the 3 types of evidence of sea-floor spreading?
Molten material that comes up over and over, magnetic stripes that show the poles have switched in the past, and drilling samples that show the age of rocks
What is subduction?
When oceanic crust converges with continental or oceanic plates, one gets pushed under the other and becomes magma
What is a transform boundary?
When plates slide past each other
What is a convergent boundary?
When plates collide (c+c, o+o, c+o)
What is a divergent boundary?
When plates separate forming trenches or sea-floor spreading, only happens at mid-ocean ridges