HOW IS A FOSSIL FORMED?
Basics Fossils are the remains of creatures that died thousands to millions of years ago. In most cases, a fossil consists of the remains of a hard part of a creature: the shell, teeth or bones. However, leaves or pieces of wood can also become fossils over time, and some fossils have the creature preserved in its entirety in amber or tar. Most creatures that die do not become fossils, since the conditions for their formation are delicate. The remains must be buried quickly, preferably in a mineral-rich ground like volcanic ash, or under a body of water or a river that can provide the remains with sediment necessary for fossilization. Types There are several methods by which fossils develop. In permineralization, the buried organic tissues of the creature are gradually replaced by the minerals in the soil, making it rock-like. Likewise, with recrystalization, crystals replace the hard materials to form a copy of the creature’s remains. Silicification occurs when the remains are replace
