chapter 2 Flashcards
What is the difference between oceanic and continental crust in terms of composition, thickness, and density?
Oceanic crust:basalt and contains iron…thinner…DENSER….
Continental:mostly granite…thicker…less dense
Compare and contrast a tectonically passive continental margin with a tectonically active continental margin. •-Which has a wider continental shelf?
Passive: Wide, flat continental shelf, gentle continental slope, continental rise
Active:Narrow continental shelf, steep continental slope, trench instead of continental rise
Which U.S. coastline is tectonically active? Tectonically passive?
Active-U.S. West coast
Passive-Gulf and East coast
Compare the continental shelf on the East and West coasts of South America. Which one is wider? Which one is passive?
East coast continental shelf is wider than the west coast continental shelf. The west coast is active and the East coast is passive
Abyssal plains are not commonly found in the Pacific. Why?
There are more abysmal plains in the Atlantic because in the Pacific the trenches trap the sediments as it comes off shore. The seiments get stuck in the trenches and does not reach the open ocean basin floor and thus does not have the opportunity to create abysmal plain
What is a submarine canyon?
Canyone that is sliced into the side of a continental slope
What forces are involved in the formation of a submarine canyon
Eroded by turbidity currents
where are submarine canyons found
May be extensions of continental stream valleys
Describe a turbidity current
Down-slope movement of water and sediment…underwater avalanche…and deposit submarine fans
Describe a submarine fan
Found on continental rise at base of submarine canyon•Fan shape deposit•Formed from turbidity currents
What is a seamount?
Volcanoes active or extinct taller than 100 meters
Describe the formation of a coral atoll
Forms from coral build up on volcanoes•Volcano sinks
What is seafloor spreading?
The oceanic lithosphere spreads from the central axis (the ridge is the axis)•Creates new oceanic lithosphere
What is subduction? Draw a cross section of a subduction zone.
Denser plate subducts(is pushed) under less dense plate•Deep sea trenchforms where 2 plates meet•Subducting plate partially melts-creating a chain of island volcanoes parallel to the trench called a volcanic island arc
Divergent plate boundaries
Which way are the plates moving relative to each other?
Plates move away from each other ← → (seafloor spreading occurs here
Divergent plate boundaries
What type of lithosphere is created?
Forms Mid Ocean ridges…mid atlantic ridge, East Pacific Rise, …..new ocean crust is formed
Divergent plate boundaries
What is a hydrothermal vent? Where are they found?
Hydrothermal vent is: underwater hot spring, rich in mineral and chemicals.
Life at the bottom chemosynthetic uses chemicals and heat to survive
Black
What is a black smoker?
The hottest of the hydrothermal vents•Contain dissolved metals that make the water dark•Home to diverse communities of marine life
Are there earthquakes or volcanoes at divergent boundaries?
Yes, there are Earthquakes and volcanic activity in the form of non-explosive lava flows
-Name 2 examples of a divergent plate boundary
Mid Atlantic Ridge, East Pacific Rise
What happens to age of the ocean floor, and depth, and heat flow from the mantle as you move away from a mid-ocean ridge? Divergent plate boundary
Gets older
Which way are convergent plates moving
towards eachother
What are the three types of convergent plates
Oceanic-oceanic convergent–Oceanic-continental convergent–Continental-continental convergent
Oceanic-Oceanic Converging
Which plate subducts
What happens to the subducting plate?
Oceanic crust is destroyed•The denser plate subducts(always oceanic)
Denser plate subducts(is pushed) under less dense plate•Deep sea trenchforms where 2 plates meet•Subducting plate partially melts-creating a chain of island volcanoes parallel to the trench called a volcanic island arc