How to Select Fossils

The term 'ashes to ashes, dust to dust' aptly describes the way most living creatures submit their physical forms to nature's recycling program. However, under the right conditions, plants and animals may emerge millions of years after their departure from this world as fossils. Just as there is multiplicity in forms of life, there is great variety among types of fossils. Knowing how to select fossils will add diversity to your collection.

Difficulty: Easy

Instructions

Learn How to Select Fossils

1. Understand how fossils form. When a dying organism is buried by sediment or volcanic ash, the decaying process is stunted due to a lack of oxygen. Over time, proteins break down and minerals replace tissue. The end result is a rock-like replica of the dead creature and the birth of a fossil.

2. Know that there's more than one way to make a fossil. Fossils that resemble a cast of a creature or plant are formed by 'authigenic preservation.' An example would be the unfortunate residents of Pompeii being buried under volcanic ash. On the other hand, 'unaltered preservations' occur when an organism becomes encased in preservation material. The mosquito being trapped in a sphere of amber in the movie 'Jurrasic Park' illustrates this kind of fossil.

3. Examine a topographical map of the region you plan to explore to get an idea of age of the rock deposits there and the type of fossils you can expect to find there. Find maps at the U.S. Geological Survey website (see Resources below).

4. Look for calcium carbonate deposits on any pieces of bone you may find. These deposits suggest that the groundwater specific to the creature's environment belongs to the ancient past. Also, bone fragments that contain mineral matter indicate that it is fossilized.

5. Inspect pieces or whole shells that you find for certain characteristics that indicate age and species. For instance, a chambered shell may belong to a pre-Mesozoic Ammonoid, while a spiral shell may suggest that a Brachiopod from the Ordovician period came to rest there.

6. Collect your finds in paper bags or boxes, taking care to provide sufficient padding to prevent fossils from making contact with each other and breaking apart.

Tips & Warnings

• Be aware that there are many examples of false fossils, or concretions, to be found. For instance, mineral deposits can form around organic materials, such as tree roots, and appear to resemble an animal fossil to the untrained eye.

Resources

• U.S. Geological Survey to select geology maps