Which statement best describes a shield volcano?

Which statement best describes a shield volcano?

• A. It has steep sides and explosive eruptions
• B. It is a wide, gently sloping mountain formed by layered lava erupted quietly
• C. It is a small cone built from ash
• D. It is formed underwater only

Answer: (B)

Shield volcanoes are built by low-viscosity lava that can flow long distances. Because the lava spills out in broad, steady eruptions, it creates wide, overlapping lava flows that pile up into a large, gently sloping mountain. This steady, flowing lava forms layered lava deposits, giving the shield-like profile, and eruptions tend to be effusive rather than explosive. That explains why the description of a wide, gently sloping mountain formed by layered lava erupted quietly is the best fit. The other options point to different volcano types: steep sides with explosive eruptions describe a stratovolcano, a small cone built from ash describes a cinder cone, and shield volcanoes aren’t formed only underwater—they can form on land as well.

Shield volcanoes are built by low-viscosity lava that can flow long distances. Because the lava spills out in broad, steady eruptions, it creates wide, overlapping lava flows that pile up into a large, gently sloping mountain. This steady, flowing lava forms layered lava deposits, giving the shield-like profile, and eruptions tend to be effusive rather than explosive.

That explains why the description of a wide, gently sloping mountain formed by layered lava erupted quietly is the best fit. The other options point to different volcano types: steep sides with explosive eruptions describe a stratovolcano, a small cone built from ash describes a cinder cone, and shield volcanoes aren’t formed only underwater—they can form on land as well.