Chapter 12 - Continental Drift Flashcards
What are 3 signs of continental drift?
Jigsaw puzzle, geological structures, matching fossils
What is the continental drift theory?
Continents weren’t always in their present locations and were once one big continent, overtime it drifted apart
What is paleoglaciation?
Old glaciers that leave rock markings behind
Where were the coal deposits?
In Antarctica
What was the key question to Wegener’s theory?
What makes continental drift?
What are tectonic plates?
Earth broken into large movable slabs
What are volcanoes? Where are they formed?
Openings in earths surface, when active they spew out gases and chunks of melted rock.
Usually around plate boundaries
What is an earthquake? And where is it found?
Ground shaking release of energy at or under earths surface
Found usually near plate boundaries
What is the Mid-Atlantic Ridge?
Ridge going from north to south down the Atlantic Ocean
What is magnetic reversal?
Earths magnetic polarity switches making north become south and vice versa
What is paleomagnetism?
The study of magnetic properties in old rocks
Explain magnetic striping.
Pattern of stripes in the direction of earths polarity on the sea floor.
What is magma?
Molten rock beneath earths surface which rises bc it is LESS dense and cools around the material surrounding it
what is a spreading ridge?
Region where magma breaks through earths surface spreading the sea floor apart making new sea floor
Sea floor spreading?
When magma rises in the spreading ridge, it spreads the sea floor adding in new sea floor
What is a hot spot?
Molten rock rises to earths surface
What is the lithosphere?
Made up of the crust and the upper mantle. Tectonic plates form the lithosphere
What is the layers of earth?
1) earths crust > made from solid granite and basalt
2) upper mantle> liquid
Lower mantle> solid
3) outer core> liquids
4) inner core> solid
What is the asthenosphere?
Partly molten layer in the upper mantle below the lithosphere
Mantle convection?
Currents in the mantle that moves the plates
What is ridge push?
New ridge comes up from sea floor pushing older material apart
What is Rift Valley?
Spreading centre that occurs in land
What is oceanic ridge?
Spreading ridge occurs in oceans
What is subduction?
Action of one plate pushing below another.
What are seismic waves?
Vibrations released by an earthquake.
What is seismology?
The study of earthquakes and seismic waves.
What are L- waves?
Surface waves, which roll along earths surface, and are last to arrive.
What are S-waves?
Secondary waves, are second to arrive, travel through solids not liquids and the ground motion is perpendicular to direction of wave travel.
What are P-waves?
Primary waves, they are first to arrive, travel through solids, liquids and gases and ground squeezes and stretches in direction of waves travel.
What is slab pull?
When the slab subduct under the mantle
What is a Plate boundary?
Region where 2 tectonic plates touch
What are the 3 types of plate boundaries?
1) divergent plate > plates are spreading apart
2) convergent plate > plates collide
3) transform plate > plates slide past each other
What is oceanic-continental plate?
When the oceanic and continental plates meet, the oceanic plate subducts under the continental plate bc of its density
What is a trench?
Deep underwater trench valley
What is a volcanic belt?
Long chain of volcanoes
What is oceanic-oceanic plate?
2 oceanic plates collide, the denser one subducts
What is a volcanic island arc?
A long chain of volcanoes formed by convergence
What is continental-continental plate?
When both plates collide, subduction doesn’t occur because of similar densities. They collide instead and form mountain ranges
What is a transform plate?
Convection currents in mantle make plates slide past each other
What are faults?
Breaks in rock layers due to sliding movement
Transform fault?
Fault that occurs at a transform plate
What is the focus?
The location of the earthquake where it starts
What is the epicentre?
Point in earths surface directly about the focus
What is a cone volcano?
A large volcano formed by molten spewing out from the volcano which then later forms after it hardens.
Lots of Lava, very violent, gas pressures buildup to have huge explosion
Form in subduction zones
What is a shield volcano?
Largest volcano, forms under hot spots, magma is thinner and less eruptive
What is a rift eruption?
Eruptions that happen through earths crust from the mantle, milder than cone volcano
Near ocean ridges or continental crust
