Volcano question!!! which type of lava thingy?
Pahoehoe lava produces caves known as lava tubes, which form when lava at the outer edges of a flow channel begins to cool and harden, first along the sides of the flow and then on top of it. Lava in the center of the encasement continues to flow until the generating source stops. Once the last of the flowing lava clears the channel, all that remains is a crusty hollow tube.
