Deep ocean trenches are surficial evidence for ________.

14) Deep ocean trenches are surficial evidence for A) sinking of oceanic lithosphere into the mantle at a subduction zone B) rifting beneath a continental plate and the beginning of continental drift C) rising of hot asthenosphere from deep in the mantle D) transform faulting between an oceanic plate and a continental plate 15) most effectively outline the edges of the lithospheric plates. A) The locations of deep mantle hot spots B) Margins of the continental shelves C) Lines of earthquake epicenters 16) _ first related the symmetrical magnetic patterns in seafloor basalts to seafloor spreading at a mid-ocean ridge. A) Matthews and Marks B) Vine and Matthews C) Evans and Novak D) Wegener and Wilson 17) Early results of the Deep Sea Drilling Project clearly justified the conclusion that A) the youngest sediments were deposited directly on the oldest seafloor basalts B) Proterozoic rocks are found only as seamounts in the deepest parts of the ocean basins c) the ocean basins are relatively young: most ocean basin rocks and sediments are Cretaceous or younger in age D) the oceans have not always contained most of Earths water 14) Deep ocean trenches are surficial evidence for A) sinking of oceanic lithosphere into the mantle at a subduction zone B) rifting beneath a continental plate and the beginning of continental drift C) rising of hot asthenosphere from deep in the mantle D) transform faulting between an oceanic plate and a continental plate 15) most effectively outline the edges of the lithospheric plates. A) The locations of deep mantle hot spots B) Margins of the continental shelves C) Lines of earthquake epicenters 16) _ first related the symmetrical magnetic patterns in seafloor basalts to seafloor spreading at a mid-ocean ridge. A) Matthews and Marks B) Vine and Matthews C) Evans and Novak D) Wegener and Wilson 17) Early results of the Deep Sea Drilling Project clearly justified the conclusion that A) the youngest sediments were deposited directly on the oldest seafloor basalts B) Proterozoic rocks are found only as seamounts in the deepest parts of the ocean basins c) the ocean basins are relatively young: most ocean basin rocks and sediments are Cretaceous or younger in age D) the oceans have not always contained most of Earth’s water

14.A The denser and heavier oceanic plate subducts beneath
another plate in a subduction zone. The zone where two plates meet
forms a long narrow depression with v shaped profile called the
trench.
15.C Most of the earthquakes occur at the boundary between two
plates due to their relative movement. So interplate siesmicity at
plate boundaries occur as lines of earthquake epicenters along
these boundaries.
16.C As Vine and Mathews first gave the hypothesis of Linear
Magnetic Anomalies. The magnetic anomalies over strips of ocean
floor (parallel to mid oceanic ridge) form due to the reversals of
ambient magnetic field of earth. These anomalies on both sides of
mid-oceanic ridge are symmetric as the spreading rate of oceanic
plate on both sides of mid-oceanic ridge is same.
17.C The oceanic crust is not older 200 million years as the
generation and destruction is limited within this time frame and
this was proved by the deep sea drilling project. The oceanic crust
is relatively younger than continental crust as it is continuously
forming a mid-oceanic ridges and getting destroyed at the
subduction zones.

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