Ray Pfefferkorn, age 12, of Phoenix, Arizona, for his question:

Why are there no fossils in igneous rocks?

Igneous rocks are formed deep in the earth's crust where conditions are hot enough to melt granite and other sturdy rocks we find on the cool surface. They well out as molten lava, which is pelted rock. Lava is hot enough to burn bones and bodies and even sturdy tree trunks to ashes. Whole forests have been burned to ashes by rivers of molten lava.

Fossils are trees and bones which have been preserved in more gentle layers of sedimentary rocks. These layers are beds of silty mud and other minerals which have dried and hardened with time. Fossil remains embedded in these materials are often preserved. Fossil remains touched by fire formed igneous rocks were burned to cinders.