Behavior of rock in slopes

The behavioral modes to which a rock slope is susceptible are many and complex. This article discusses a long but not exhaustive list of common failure styles; highlighting observable characteristics that distinguish one from another. Slopes in both strong and weak rock masses are considered. Principles are stated to explain how and why different failure modes develop in different rocks. The discussion is illustrated with examples of diverse failure modes in foliated metamorphic rocks developed in the walls of an eroded spillway runout.