Which term describes tall mountains formed by alternating lava and ash layers?

• A. Composite volcano
• B. Cinder cone
• C. Shield volcano
• D. Lava dome

Answer: (A)

Tall mountains formed by alternating lava flows and ash layers arise when eruptions alternate between viscous lava that piles up near the vent and explosive expulsions that deposit ash and tephra. Over time these alternating layers build a tall, layered cone with steep sides. This pattern is the hallmark of composite volcanoes, which combine hardened lava flows and tephra to create the characteristic striped structure.

Other shapes don’t fit this layered, tall-cone image. Cinder cones are built mainly from loose tephra ejected during eruptions and usually stay relatively small with steep sides. Shield volcanoes form from very fluid lava that spreads out into broad, gentle slopes rather than stacking layers. Lava domes are produced by highly viscous magma that oozes up and piles into a dome near the vent, not a tall layered mountain.