Final Answer:
1. Shield volcano — broad, gently sloping dome — basaltic lava (low silica, low viscosity)
2. Stratovolcano (composite) — tall, steep, symmetrical cone — andesitic to rhyolitic lava (high silica, high viscosity), alternating layers of lava and ash
3. Cinder cone — small, steep, conical hill — basaltic to andesitic pyroclastic fragments (scoria/cinders), short-lived eruptions
a. As the silica content increases, the magma becomes more viscous (thicker), which traps gases and leads to more explosive eruptions. Low-silica magma flows easily and produces gentle, effusive eruptions.
b. Higher silica content → higher viscosity → more trapped gas → more explosive eruption. Lower silica → lower viscosity → gas escapes easily → quieter, flowing eruption.
Parent Tip: Review the logic above to help your child master the concept of volcano types worksheet.
