From Bushwalk Australia
In Tasmanian bushwalking literature, the term "scree-field" is often used to describe a large area covered in scree. Some mountain tracks and routes in Tasmania cross scree-fields, and the negotiation of these fields can vary in difficulty due to the size of the rocks, the steepnes of the slope, the stability of the rocks, and in some cases, how much water, snow, ice or moss is on the rocks to make them slippery.
Scree is formed by water filling cracks and crevices in the rock on a mountainside, then freezing. When the water freezes the subsequent expansion can cause the rock to break off.