Plate Tectonics & Boundaries
What are plate tectonics?
Pieces of lithosphere that move on top of the asthenosphere.
What is a seamount?
An undersea volcanic peak.
What is a caldera?
A crater that exceeds 1 km diameter.
What type of volcano(es) are the Hawaiin Islands?
Hotspot volcanoes.
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Free Point!
What widens as the lithosphere is created?
Seafloor.
What enlarges seamounts?
Lava from countless eruptions.
What are shield volcanoes? How do they form?
Volcanoes that are built up from a steady supply of fluid basaltic lava; when lava erupts, lava pours out in all directions to form thin, sloping sheets.
What is the oldest and youngest island? What are the most active places of the Hawaii Islands?
Oldest: Kauai Youngest: Hawaii
Most active places: Mauna Loa and Kahoolawe
What is the percentage of volcanoes present in the Ring of Fire?
75% of volcanoes reside there.
What causes plate tectonics? What is the average speed?
Gravity and convection currents in the mantle. Average speed: 4 cm per year.
What are mantle plumes?
Soft rocks that make their way to the surface.
How do the calderas form? Why?
When the summit of a volcano collapses into a partially emptied magma chamber; explosive eruptions destroy portions of the volcano.
How many islands are there in the Hawaiian Islands? Where are the Hawaiian Islands located? What is the area in which they are located called? Give one fact about this area.
There are 8 major islands. The Hawaiian Islands are located in the North Pacific Ocean in an area by the name of Polynesia.
Polynesia: 1. It is a subregion of Oceania 2. It is made up of more than 1000 islands all over the northern and southern Pacific Ocean 3. Shaped like a triangle.
What is the Ring of Fire?
A horseshoe-shaped region in the Pacific Ocean.
What are convergent boundaries? What is it most responsible for? What are the examples of convergent plate boundaries?
Plates that move towards each other; responsible for producing the tallest and deepest structure on earth.
Examples: Mountain Everest and the Marianna Trench.
What is the process that helps the mantle rock that is on top of the hotspot move called and what does it do? What happens to the rock when it goes up to the surface?
The process is called convection. It is when heat transfers because of the movement of a fluid, liquid or gas between areas of different temperature.
The rock hardens and erupts because of the convection currents.
How do cinder cones form? Give examples.
Form from various ejected materials (ex. Ash, cinders, glass…) that erupt from a single vent and pile up.
The Hawaiian Islands formed due to what? Explain what this is.
The Hawaiian islands are above and formed due to intraplate hotspot, which have volcanoes that don’t occur on plate boundaries but occur in the middle of oceanic plates.
Where do tectonics plates meet? What are they created by?
Tectonic plates meet at subduction zones created by convergent boundaries.
What are divergent boundaries? What do they form? What are the examples of divergent boundaries and give one fact for each example?
Plates that move apart; they form rifts and new parts of the ocean.
The Gakkel Ridge: 1. plate boundary between the North American Plate and the Eurasian Plate. 2. located in Greenland and Siberia 3. Named after Russian polar explorer Yakov Yakovlevich Gakkel.
Lake Tanganyika: 1. waters pass through Tanzania, Burundi, Congo DR and Zambia. 2. longest fresh water lake in the world 3. deep because it lies in the Great Rift Valley.
What is the relationship between seamounts and hotspots? How do volcanoes become extinct? What grows over the hotspot?
Seamounts are mostly found on hotspots.
when the plates move, the lithosphere moves away and the volcano, with time, will lose its source of magma and becomes extinct.
New volcanic island grows over the hotspot.
What is the difference between composite and cinder cones?
Cinder cones don't rise higher than 300 m.
How were the Hawaiin Islands formed? Why do the islands become extinct?
The superheated area of magma rises up and burns a hole through the crust. It starts to form a volcano which builds with time until it forms an island in the middle of the ocean. The crust moves away from the intraplate hotspot which allows the formation of another island and as the islands move away from the intraplate hotspot, they become extinct because there is no more heat to fuel them.
What is the difference between hotspot volcanoes and normal volcanoes? (Name 3)
Hotspot: occur within the plate, can be extinct, located on hotspots.
Normal: 1. occur at plate boundaries 2. cannot become extinct 3. are located in divergent/convergent boundaries (NOT on hotspots).