Geological Processes Flashcards
Who proposed continental drift and when?
Wegner in 1916
Evidence of continental drift
- South America and Africa can puzzle piece together
- the parts that fit together have similar rock frequencies
- the parts that fit together have shared plants
Why would continents move?
Continents are on drift and subduct under each other when they collide and new crust wells up from the rifts.
What is the mid Atlantic ridge?
- evidence of see floor spread
* on either side of this ridge, magnetization of sea floor rocks switch every few kilometres
Why do tectonic plates move?
The driving energy source is convection in the mantle of the earth.
What is convection?
A method of heat transfer in a fluid. Hot fluid moves up while cold fluid moves downward.
What is a divergent plate boundary?
Two plates that split apart usually at ocean ridges, upwelling of molten lava emerges from these ridges-ex. Mid Atlantic ridge, rift valleys of Eastern Africa
What is a convergent plate boundary?
Plates collide together, one sinks below the other(subduction), mountains build up and volcanic activity or earth quakes occur-ex the alps
What is a transform plate boundary?
Plates slide past one another causing earthquakes-ex. San Andreas California
What does subduction mean?
When plates collide and one is “subducted” or sinks below the other, building a mountain.
What is a hot spot and examples of where?
•place where magma plumes rise out of the mantle
•crust is hotter here
•leads to volcanoes and hot springs
Ex. Hawaii, Yellowstone
What is an island arc and example of where?
•moving plates over a hot spot creates a succession of volcanoes.
Ex. Hawaii
What is magma?
A hot substance that is within or below the earths crust that is turned into lava or igneous rock when cooled.
Lava erupts through an opening in the earths crust called a…
Vent
A bowl shaped depression that forms around the vent of a volcano is a…
Crater
Rock fragments that are thrown into the air during a volcanic eruption are called…
Tephra
The smallest tephra are…
Dust
Fast moving clouds of gas, ash, and other tephra are…
Pyroclastic flows
What is formed when the top or side of a volcano collapses into the magma chamber?
Caldera
Large angular volcanic fragments are called…
Volcanic blocks
When magma reaches the earths surface it’s called…
Lava
Large rounded or streamlined tephra are called…
Volcanic bombs
What is a composite volcano?
•medium sized with a curve •forms in layers of tephra and lava •fuelled by magma that contains large amounts of silica, water, and gase •potentially most dangerous volcano Ex. Mount St. Helens & mount rainier
What is a cinder cone volcano?
•forms when tephra are ejected into the air and pile up around a vent
•small steep volcanoes
Ex. Lava butte in Oregon
What is a shield volcano?
•broad gently sloping sided and a nearly circular base
•forms when layers of basaltic lava accumulate during non explosive eruption
Ex. Mauna Kea
What is an earthquake?
Wave motion of the earth caused by sudden massive dislocations.
What is a longitudinal wave or “p-wave”?
- particle motion is parallel to the wave direction
- can pass through fluids
- the fastest speed of wave
- bend when striking the core•
What are transverse waves or “s-waves”?
- particle motion is perpendicular to the wave direction
* they cannot pass through fluids
What is a surface wave?
•do the most damage and go the least distance