Planet Earth Ch4 Smartworks

Order the steps of volcanic island arc formation.

1. A subduction trench forms where the subducting plate bends downward into the mantle 2. An accretionary prism begins to form 3. Magma, created by flux melting of the mantle, rises through the overriding plate 4. Lava erupts onto the surface, forming volcanoes

Place the events in the order they occur between the mid-ocean ridge and deep-ocean trench. - oceanic crust recycled into mantle - oceanic crust created - oceanic crust scraped off plate to form accretionary wedge - sediment accumulates on oceanic crust

1. oceanic crust created 2. sediment accumulates on oceanic crust 3. oceanic crust scraped off plate to form accretionary wedge 4. oceanic crust recycled into mantle

Identify statements true of the lithosphere and asthenosphere. A.The asthenosphere "floats" on the lithosphere. B.The asthenosphere underlies the lithosphere. C.The lithosphere is denser than the asthenosphere. D.The asthenosphere is relatively soft compared to the rigid lithosphere.

B.The asthenosphere underlies the lithosphere. D.The asthenosphere is relatively soft compared to the rigid lithosphere.

The chain of Hawaiian islands can be used to calculate the rate of movement of the Pacific Plate over the last few million years. The island of Hawaii currently sits on the hot spot and is therefore 0 million years old. The island of Oahu used to sit on the hot spot and is now approximately 360 km away from the hot spot, to the northwest. If the average plate motion is 9 cm/yr, how old is Oahu (Remember to convert your units properly!)

C. 4 my (convert km to cm, then divide that by the 9cm - that is the answer)

Contrast continental collision and volcanic island arc formation. Sort properties of each. - involves continental crust - involves subduction - involves volcanism - involves oceanic crust Continental Collision Volcanic Island Arc Formation

Continental Collision: (involves continental crust) Volcanic Island Arc Formation: (involves volcanism, involves subduction, involves oceanic crust)

According to the mantle plume model, hot-spot plumes... A. stream upward quickly because their hot magma is less dense than the overlying rock. B. partially melt the base of the overlying crust, and the magma that is formed becomes a large magma chamber. C. produce volcanoes that always coincide with a plate boundary. D. are thought to originate at the core-mantle boundary.

D. are thought to originate at the core-mantle boundary.

According to current plate tectonics theory, A. plates move around by convection on the uppermost part of the mantle. B. a continental plate will subduct under an oceanic plate when the two converge. C. plates move at speeds of a few meters per year. D. plates are composed of the crust and the uppermost part of the mantle.

D. plates are composed of the crust and the uppermost part of the mantle.

Decide which type of plate boundary the following items would most likely be associated with. - crustal thinning - crustal thickening - andesitic volcanism - shear stress Divergent Boundary Convergent Boundary Transform Boundary

Divergent Boundary: (crustal thinning) Convergent Boundary: (crustal thickening, andesitic volcanism) Transform Boundary: (shear stress)

Categorize processes related to transform boundaries. Sort the following processes those likely to be related to a transform boundary or those likely associated with other boundary types. - divergence - earthquakes - convergence - subduction Transform Boundary Other Boundary

Transform Boundary: (Earthquakes) Other Boundary: (Subduction, Convergence, Divergence)