Rockfalls are the downslope movement of loose rocks, either through free fall or by rolling. Rockfalls commonly involve individual boulders, although landslides may be triggered if these boulders impact the slope. Clasts may be dislocated by erosion beneath the clast, freeze-thaw processes or human intervention. Incidences of rockfalls in Newfoundland and Labrador are shown on the map below.
(click on a teardrop to obtain information on a hazardous event in that location)
The expansion of the town of Springdale led to the 1972 development of a new subdivision adjacent to a highly fractured basalt cliff. Several rockfalls from this cliff over the next few years resulted in property damage. A youth was killed in April 1984, while climbing on the slope, when a large boulder toppled and crushed him. In response to these incidents, extensive engineering works were undertaken by the Department of Municipal Affairs to stabilize parts of the cliff face. In 1986, a retaining wall was constructed at a cost of $286,000 to protect 11 houses that were built along the foot slope.
Slope stability is a major problem in highway construction throughout the province. Transportation routes are occasionally cut by landslides, affected by minor rockfalls, or have problems with gullying and minor debris flows on road cuttings. New highway expansion and construction near Gambo incurred major difficulties where the highway abutted a steep slope of unconsolidated sediments.Considerable remedial engineering work has been undertaken to protect the road in this area at estimated costs of $650,000 or more.
Images and text reproduced by permission of M. Batterson, D.G.E. Liverman, J. Ryan and D. Taylor, The Assessment of Geological Hazards and Disasters in Newfoundland: An Update. (St. John's: Government of Newfoundland and Labrador, Department of Mines and Energy, Geological Survey, © 1999) unless otherwise noted.