Question

There is a deep trench in the sea floor off the Marianas volcanic arc of explosive, andesitic, Ring of Fire volcanoes in the South Pacific, but the water is not deep off the coast of Oregon and Washington near Mt. St. Helens and the Olympic, because:_________.
A) The Marianas, Oregon and Washington have trenches, but the trench off Oregon and Washington is filled by discarded Microsoft Windows CDs that are obsolete because of all the virus problems.
B) Oregon and Washington are near a subduction zone, but the Marianas are not.
C) The Marianas, Oregon and Washington have had the sea floor bent downward by subduction to make trenches, the trench off Oregon and Washington is filled by sediment eroded from the nearby continent, but the Marianas don't have a nearby continent and so the trench there is not filled with sediment.
D) The trench off Oregon and Washington is filled with great basaltic lava flows from the hot spot that feeds the Cascades volcanoes.
E) The Marianas are near a subduction zone, but Oregon and Washington are not.

Answer 1

Answer:

C) The Marianas, Oregon and Washington have had the sea floor bent downward by subduction to make trenches, the trench off Oregon and Washington is filled by sediment eroded from the nearby continent, but the Marianas don't have a nearby continent and so the trench there is not filled with sediment.