Fossils are the remains, impressions or traces of animals and plants from long ago which have been preserved within rocks.
They help us to understand how life has evolved over time. Fossils come in many forms, they may be shells of bivalves, dinosaur footprints or the delicate impressions of leaves. The state of preservation of fossils varies greatly depending on the structure and composition of the original organism, the type of rock they are preserved in as well as what has happened to that rock since deposition.
There are three main types of fossils;
- a body fossil, such as an ammonite shell,
- a trace fossil, patterns left by animals such as dinosaur footprints, and
- chemical fossils which can be detected geochemically in the rocks.
In the Tees Valley we find many examples of the first two types.
Most animals and plants are eaten either on, or after death and their chemical constituents recycled. A few, however, find their way into quiet areas where sediment is accumulating. Even fewer survive the violent upheavals of our planet. Only a tiny fraction of the fossils which do form are ever found and studied.