Fountains of liquid rock light up the night.  As the rock is tossed up into the air it begins to cool and harden.  It may plop down as a soft lump or a cinder-like piece of rock filled with bubbles.

     The bubbles are caused as gases and water in the rock expand.  The gases have been released from the pressure of tons of rock pressing down on them and they expand and escape into the atmosphere, leaving the shapes of their broken bubbles in the rocks.

     As we learned in States of Matter, physical substances can exist as solids, liquids, and gases. Temperature affects which state they will be in.

     We are used to seeing all three states with water.   We have seen ice, liquid water, and steam. Still, it is hard to think of rock as being liquid. Volcanic eruptions show us liquid rock, and, when the lava cools, the rocks are often preserve patterns that look like flowing streams or thicker liquids.

     Here is some lava that has just begun to cool. Look at the rock surface wrinkling as the soft molten lava spreads out. This rock is becoming pahoi-hoi lava with its smooth wrinkled coils.

     Notice how the shell-shaped piece of lava at the upper right side of the picture has cracked. Many substances expand when they are heated and contract when they cool. As this rock cooled it contracted so much that it cracked in several places.

     When wind blows dust and ash over the lava fields, some of the small particles will blow into these cracks. Life will begin to take root in cracks like these.