Ontario Geological Survey the rock (bedrock); b) the deposits of sand, gravel, and till left by the glaciers; c) the mineral resources and potential; d) the energy resource potential within the rocks and soils; and e) the groundwater aquifers that contain groundwater resources. An understanding of what is at, and below, our feet is fundamental to human existence on the Earth, to understand the environment and habitats, and our ability to adapt to future changes, such as global warming. This geological knowledge is used to assess Earth resource potential, to attract investment, to ensure the health and safety of Ontario people from geo-hazards,
Silt out zero visibility. Always using guidelines during penetration dives is an important safety measure as it helps divers find their way out. Surface supplied divers are generally at less risk from silt out as they are connected to the surface by an umbilical and can not get lost, but they may become disorientated, and unable to work effectively. It is also more likely for them to have an umbilical snag in bad visibility, and if assistance is required from the stand-by diver, this is more difficult in a silt out. A severe silt out will make the video cameras on a