The effects of temperature also influence the performance of a rock slope. Large temperature changes can cause rock to spall due to the accompanying contraction and expansion. Freezing of water in discontinuities causes more significant damage by loosening the rock mass. Repeated freeze cycles may result in gradual loss of strength. Except for periodic maintenance requirements, such effects are a surface phenomenon and are most likely of little concern for permanent slopes. However, in a few cases, surface deterioration could trigger slope instability on a larger scale.