These volcanoes form steep sided mountains and have violent eruptions.

• A. Cinder Cones
• B. Shield Volcanoes
• C. Caldera
• D. Stratovolcanoes

Answer: (A)

Volcano shapes and eruption styles are controlled by magma viscosity and gas content. Steep-sided, tall mountains that erupt violently are characteristic of stratovolcanoes. They build up from alternating layers of viscous lava and erupted ash, pumice, and other tephra. The silica-rich magma traps gases, allowing pressure to build until explosive eruptions blast out ash clouds, pumice, and pyroclastic flows, creating a powerful and often destructive eruption that helps form tall, cone-like mountains with steep slopes. This differs from cinder cones, which are smaller, cone-shaped piles formed from tephra that falls around a vent, producing a steep but relatively low hill. Shield volcanoes have broad, gently sloping profiles built from low-viscosity lava flows and erupt mainly effusively rather than explosively. Caldera refers to a large basin formed when a volcano collapses after a major eruption, not a mountain. So the description points to a stratovolcano.