Layers
List the layers of the Earth in order from the outside in.
Crust, mantle, outer core, inner core.
Who is credited with this theory?
Alfred Wegener
What is the theory of plate tectonics?
The Earth's crust is broken into pieces, called plates, that move around and interact with one another
What is a fold?
Bending and crumpling of rock without breaking
Which layer of the Earth do we know the most about?
What is the crust. It is the only layer we can directly observe. (Can't go any deeper)
What is the name of the combined land mass that Wegener named when studying continental drift?
Pangaea
Which two layers of the Earth do we need to know the most about to understand plate tectonics (which two are most involved)?
crust and mantle
What is a syncline?
A fold in rock that bends downwards like a 'U'.
Most earthquakes occur along which type of boundary?
Transform - plates sliding past each other
What happens to the layers of the Earth as they get closer to the center (or inner core)?
The layers get hotter and denser as they get closer to the center (or inner core)
What types of evidence did Wegener propose supported his theory of Continental Drift?
Fossils, Rock formations, Jigsaw coastlines
How is plate tectonics different than continental drift?
Plate tectonics explains the why and how behind the movement of the continents.
What sort of forces cause strike-slip faults?
Shearing forces
What EVENTS do we often see occurring at plate boundaries?
Earthquakes and volcanoes
What is the state of matter of the outer core and how do we know?
Liquid - S-waves from earthquakes cannot travel through it
Wegener had LOTS of evidence based on observations he had made, so why wasn't his theory accepted by the scientific community?
He couldn't explain why or how these large continents could move around.
Which three main forces contribute to the movement of tectonic plates?
mantle convection currents, ridge push (new oceanic ridges), slab pull (sinking of denser plates).
How is a fault formed and what three forces are involved?
One part of Earth's crust moves relative to another. Caused by compression, tension or shearing forces
What is subduction and where does it occur?
Bonus: What phenomena (events) are commonly seen there?
At convergence plate boundaries, when one plate (older, oceanic crust) sinks under another plate (continental or younger oceanic crust).
Ocean trenches and volcanoes (eg. Ring of Fire volcanoes)
What is the state of matter of the inner core and why?
Solid - even though it should be a liquid, the pressure at the centre of the planet is too great.
What characteristics of the sea floor (once discovered) assisted in acceptance of the theory of Continental Drift (and Plate Tectonics)?
Deep ocean trenches, ridges and abyssal plains provided evidence of sea-floor spreading, which explained that plates were moving and dynamic.
How does ridge push result in new crust being formed?
rising magma in the mantle causes tectonic plates to move apart bringing fresh material to the surface to make new crust.
How is a horst formed?
Segments of raised crust surrounded by normal faults and graben (rift valleys).
What happens at the site of convergence collision plates?
continental crust crumples and folds together to form huge mountain ranges