A bog is an unusual place formed under very particular conditions. Camosun Bog's history can be traced back ten thousand years. What were the special conditions that allowed it to form, and what were some of the changes it went through during its evolution?

The glaciers that advanced over south-eastern British Columbia 25,000 years ago took over the landscape. They destroyed all living things that could not escape and brought the arctic winter to the south.
For over 10,000 years a moving layer of ice over a kilometre deep scraped over the earth. When the ice receded about 12,000 years ago it left the land scoured clean. Gradually life came back. It is here that our story begins with a small depression in the land formed by the weight of an enormous block of ice.

The depression left after the ice receded filled with water and a lake was created. Along the shallow edges of this lake, sedges and cattails grew. Streams continued to feed the lake bringing in more sediment.

Gradually the lake filled in, becoming shallow throughout, and plants were able to grow over the whole area. In place of a lake a swamp formed. This happened about 5,000 years ago.

Between 5,000 and 2,000 years ago the area remained a swamp with fast-growing sedges and grasses. As these plants grew, the dead leaves and stalks fell into the water and eventually blocked the streams carrying in the fresh water and nutrients the swamp depended on. The oxygen in the water was used up in the process of rotting of the dead plants.
The standing water with low oxygen and no replenishment of its nutrients created conditions allowing the invasion of sphagnum moss. For the last 2000 years this sphagnum has maintained the conditions of high water level and low nutrient and oxygen levels characteristic of a bog.
Only in the last 90 years have things begun to change due to human interference.