A talus slope is formed when debris from a weathering rock piles up to a certain angle of repose, according to About.com. These slopes usually lie at a very steep hill or under a cliff.
In areas that experience winters, talus slopes are formed from frost weathering as freezing water expands and shatters the rock into small pieces. Additionally, a talus slope can be formed from chemical weathering, which hydrates minerals in a rock to become heavier and fall to the bottom of a cliff. Over a long period of time, the piles of rocks at the bottom of steep cliff grow to become a talus slope. Climate determines how a talus slope is formed, as it affects how the weathering process takes place.