Fossils: Four Questions And Answers

What Are Fossils?

Fossils are the remains or impressions of animals and plants which lived in prehistoric times. In Ontario, we have some of the richest fossil bearing rocks in the world, providing fossil hunters with countless examples of the type created by animal impressions.

Where Do Fossils Come From?

During the Ordovician, Silurian, and Devonian periods (350 to 450 million years ago), most of Ontario was under water. More recently, during the Pleistocene Period (10,000 to 1,000,000 years ago) giant glaciers were advancing and retreating over the entire Bonnechere Valley. These conditions allowed many species of early animals, especially water dwellers, to live and die in our area.

How Are Fossils Formed?

When an ancient creature, such as a trilobite, died, it floated down to the sea bottom, where was gradually covered with sand, silt and other organic material. Over hundreds of years, the layers above the dead creature gradually deepened, although water could still reach it. As the layers turned to rock, a chemical reaction between the animal’s shell and the minerals carried in the water caused the shell to be replaced, molecule by molecule, with calcite or silica. After this replacement process had been going on for about 100,000 years, the original shell had been completely carried away by water, and in its place was an exact replica in stone. Once the surrounding layers turned to stone, the fossil lay preserved, awaiting discovery by fossil hunters.

Where Can I See Some Of These Fossils?

Bonnechere Museum’s has a collection of fossils, which you can view and learn from. However, the “fossil hunts” conducted from the museum every summer are an opportunity to apply what you have learned about fossils. Travelling with other fossil hunters, you, yourself, can discover real Ordovician fossils.

Resource: R.R.H. Lemon, Fossils In Ontario