the earth's atmospheric temperature started to rise, the glaciers melted. Sand, silt, and clay were deposited on top of the ground, which prevented water drainage at this location. This created a big pool of glacial water that had no means of escaping or draining. 6,000 years after glacial melting, the aquatic environment was capable of preserving dead plant material in the form of peat. At this time, peat was composed of grass and woody plants. The depression did not contain sphagnum moss until 3,000 years later. As the peat deposits increased, the main water source changed from nutrient-rich flood water and ground water to nutrient-poor rainfall. Continuous organic matter build-up on the surface of the depression made the peat more acidic. The surface of this wetland slowly separated from groundwater sources, and the environment switched from a fen to a bog. A fen contains more nutrients than a raised peat bog; ergo, the ecosystems are very different. Many years after the appearance of sphagnum moss in the depression, peat accumulated thickest near the centre of the bog. Today, there are 12 species of sphagnum moss that can be found in Burns Bog. Hydrology Burns Bog receives water primarily from rainfall. Water is used by the plants via evaporation, or moved into the air via transpiration. Proper hydrology of the bog is critical to its survival. The water level needs to be high enough so that it can sustain growth of sphagnum moss. A low water table in bogs can lead to irreversible drying of bogland, which can be detrimental to its ecosystem. In Burns Bog, the water table fluctuates at different times in the year. The water table tends to be high in the fall and winter periods, but drops during the summer months. Biodiversity There are more than 14 different plant communities in Burns Bog. The most important as deemed by the City of Delta are "peat-forming". Peat-forming plants are those that grow in places with a high water table (e.g. sphagnum mosses). Cloudberries, crowberry, velvet-leaf blueberry, and bog-rosemary are some of the rare plants found in Burns Bog. Carnivorous plant populations reside in the bog as well. The sundew plant can be found in the conservancy area and in the Delta Nature Reserve. Many skunk cabbage plants are seen in the Delta Nature Reserve during the summer months as well. Burns Bog is home to many animal species.