Tall, cone-shaped mountains in which layers of lava alternate with layers of ash.

Tall, cone-shaped mountains in which layers of lava alternate with layers of ash.

• A. Composite volcano
• B. Shield volcano
• C. Lava dome
• D. Caldera

Answer: (A)

This describes a composite volcano, also called a stratovolcano. The layered structure comes from repeated cycles of explosive eruptions that eject ash and pumice, followed by lava flows that solidify into new rock. The magma is highly viscous, so gases build up and eruptions are violent, creating tall, steep-sided cones with alternating layers of ash and lava. These volcanoes commonly form at destructive plate boundaries where subduction brings magma to the surface. In contrast, shield volcanoes have low-viscosity lava that spreads into broad, gentle slopes; lava domes are smaller, rounded mounds of viscous lava that don’t form tall layered cones; calderas are large depressions from the collapse of emptied magma chambers, not layered cones.

This describes a composite volcano, also called a stratovolcano. The layered structure comes from repeated cycles of explosive eruptions that eject ash and pumice, followed by lava flows that solidify into new rock. The magma is highly viscous, so gases build up and eruptions are violent, creating tall, steep-sided cones with alternating layers of ash and lava. These volcanoes commonly form at destructive plate boundaries where subduction brings magma to the surface. In contrast, shield volcanoes have low-viscosity lava that spreads into broad, gentle slopes; lava domes are smaller, rounded mounds of viscous lava that don’t form tall layered cones; calderas are large depressions from the collapse of emptied magma chambers, not layered cones.