Pyroclastic material includes lava that hardens in the air during eruption. a. True
b. False

True, a common cause of Pyroclastic flows is gassed expelled from a volcano during an eruption as well as dense, fast moving solidified lava pieces.

True Pyroclastic flows contain a high-density mix of hot lava blocks, pumice, ash and volcanic gas. They move at very high speed down volcanic slopes, typically following valleys.