Question

identify features of the sea floor. 5 of 5 how did this island chain located to the north of the trench form? the island chain formed in the middle of a rifting zone where magma erupted to form mountains. the mountains chains formed from terminal moraines from the pleistocene ice age. oceanic crust is subducting under other oceanic crust, partially melting, and that melt is rising and forming a chain of volcanoes. it formed as the sea level rose and flooded continental crust leaving only the mountains sticking up above sea level.

Explanation:

To determine how the island chain (north of the trench) formed, we analyze each option:

1. Rifting zone (mid - ocean ridge) forms new crust, not island arcs near trenches. Eliminate this.
2. Terminal moraines (glacial deposits) form on land, not oceanic island chains. Eliminate this.
3. Island arcs form at ocean - ocean subduction zones: one oceanic crust subducts under another, melts (due to pressure/temperature), and the melt (magma) rises to form volcanic islands. This matches subduction - related island arc formation.
4. Flooded continental crust forms continental islands (e.g., Hawaii is volcanic, not continental). Eliminate this.

Answer:

Oceanic crust is subducting under other oceanic crust, partially melting, and that melt is rising and forming a chain of volcanoes.