Cliff Safety
It is obvious that we should stay back from cliff edges to ensure we do not lose our balance and fall. However, in our industry, we also know that the cliff itself can be unstable, making it all the more important to stay back a safe distance. Even hot weather can cause parts of cliffs to collapse.
Landslides and rock falls occur frequently. Sometimes the geological processes that cause them are slow, such as erosion over many years or decades. However, those slow geological processes can cause sudden, unexpected collapses, even at sites that seem stable and safe. For example, sea arches have collapsed in recent years at several locations around the Bay of Fundy.
Also, a cliff partially collapsed at Wassons Bluff, Cumberland County, in 2017 and threw debris quite far out from the cliff. (The collapse was captured on time lapse video: https://museum.novascotia.ca/fr/node/1989).
Landslides and rock falls can also be caused by much faster processes, often related to weather events such as heavy rain.
In 2022, as a heat wave began in England, the British Geological Survey warned that heat can cause rocks to expand and, as they cool, pre-existing cracks can widen and new cracks can form. These fluctuations in temperature can increase the risk of rock falls.
Nova Scotia’s coastal areas are particularly dynamic and ever-changing given the effects of wind and water. It is important to avoid going directly under or near cliffs edges.
At mines and quarries, there are a number of safety standards and regulations designed to prevent accidents associated with rock falls.
For example, we stay back at least 10 feet from the edges of cliffs/rock faces to avoid falling. Anyone required to work closer to the edge must wear fall arrest gear (i.e. a harness and lifeline that stop falls). For example, people preparing blasts, which bring down rock faces as rubble so the rock can be collected, often need to wear fall arrest gear.
After a blast, an excavator or scaling machine knocks any loose rock and overhangs down so they will not fall unexpectedly.
Surface mines/quarries are designed to have different levels, or what we call benches. Government of Nova Scotia regulations require a bench for every 20 metres vertically mined along a rock face so any falling rock can only fall that distance, and not the full the depth of the mine. This limits its destructive force. (Benches and roadways can be seen on the right of the picture below from the Moose River gold mine.)
At the bottom of a rock face, vehicles park on the opposite side of the road so the cab is as far as possible from potential falling rock. Also, anyone on foot must stay back at least the height of the rock face in case it collapses. Hard hats are also worn at all times, something anyone, including rock or fossil collectors, walking near the base of a cliff should also do.
Nova Scotia’s mining and quarrying industry has reduced its injury rate by 90% since the 1997 Westray public inquiry report by taking safety matters like this extremely seriously.
We encourage all Nova Scotians to be careful when near cliffs or other potentially dangerous areas while doing outdoor activities and enjoying our beautiful province.
The Moose River gold mine in 2022.
