Ch 9 Volcanoes 2021

Volcanic activity is common along the Mid-Atlantic Ridge. This activity occurs at a

• break in continental crust

• divergent boundary

• subducted plate

• mantle plume

Which pyroclastic material consists of large blobs of magma that harden in the air?

• ash

• lapilli

• bombs

• blocks

Which lava pours out quickly, forming a brittle crust that is torn into jagged pieces as the molten lava underneath continues to move?

• pillow lava

• blocky

• aa

• pahoehoe

as you move northwest through the Hawaiian Islands, the age of the islands increases. The older islands are northwest of the newer islands because they

• age faster than those to the east.

• formed first and were moved away from the hot spot.

• were made of less lava than the southeastern islands.

• formed from old, recycled, silica-rich magmas

The place where two tectonic plates collide is called a

• mantle plume

• rift

• divergent boundary

• convergent boundary

Lava fountains are _____ eruptions that can spray lava into the air.

• pyroclastic

• implosive

• nonexplosive

• explosive

Where would you expect to find a long chain of volcanoes?

• at convergent boundaries

• above hot spots

• above subducting plates

• all of the above

Which lava is so thick in consistency that it barely creeps along the ground?

• pillow lava

• blocky lava

• aa

• pahoehoe

Rock melts and forms magma when

• the color of the rock changs

• the pressure on the rock decreases

• the temperature of the rock increases

• both (a) and (b)

Which of the following eruptions may resemble a nuclear explosion?

• implosive eruptions

• explosive eruptions

• nonexplosive eruptions

• fissure eruptions