Still, it is hard to think of rock as being liquid. 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. Elizabeth Anne Viau and her licensors. All rights reserved.