Gayle Siverman, age 12, of Chicago, IL., for her question:
Why is amber called a fossil?
We tend to think that a fossil is an old bone. Vast rooms in museums are filled with fossil skelrtons of giant dinosaurs and other animals that once walked the earth. But a slab of rock may also be a fossil, and we burn fossil material in our grates. A lump of glassy amber is also a fossil.
The word fossil is coined from an older word meaning to dig. As a rule, a fossil is dug up from the ground. Where it has been buried a long, long time. It may be made from stone. However, it is different from the rocky minerals of the earth's crust in one important respect. A fossil was formed by some plant or animal that once lived.
Coal is a fossil substance, because it was formed from ancient forests. It is the carbonized remains of once living plants. Limestone is a fossil rock in which the fossil shells of tiny sea dwellers are cemented in a solid mass. The pores in a fossil dinosaur bone may be filled with ordinary minerals of the earth's crust. Petrified wood is a fossil in which the plant cells are replaced, ce11 by ce11, with ordinary minerals.
A lump of amber, looking like frozen honey, is one of the most beautiful of all fossils. It is a durable gob of resin formed by an ancient conifer tree. Pines, firs and other conifers still form gooey resins in their cells, and the tangy, tacky material protects them from the cold and from attacking insects.
When a conifer tree is cut or damaged, resin flows out to seal up the wound. New wood often grows around this durable bandage, and the lump of resin becomes buried inside the tree. When the tree dies and decays, the sturdy lump of resin is left behind, perhaps to be found ages later as a lump of glassy gold amber.
In past ages, stately forests of conifers grew in the regions of europe now occupied by the alps and their sister mountains to the east. The face of the earth changed, and woody treea perished and decayed. But their gobs of hardened resin did not decay with the wood. In time they became amber. Lumps of amber from the ancient conifers are often washed up on the shores of the baltic sea.
The fresh resin that flaws from a damaged conifer is shiny and very sticky. Sarnetimes an insect explores the tempting material. It gets stuck and maybe engulfed by more flowing resin. Its small body is sealed from the air. There it stays, imprisoned in its glassy tomb, while the gob of resin hardens and becomes amber.