If you're writing a geologic paper, talus is the preferred term, but scree is more fun to say. This example is near Höfn, Iceland.
Mechanical weathering breaks down exposed bedrock into steep piles and talus slopes like this before the minerals in the rock can alter into clay minerals. That comes much later, after the talus is washed and tumbled downhill, turning to alluvium and eventually into soil.
A talus slope is dangerous terrain. The material is sitting at its steepest possible slope—its angle of repose. A small disturbance, such as your misstep, can trigger a slide that may injure or even kill you as you go downhill with it. Also, there is no geological information to be gained from walking on scree.
Another picture of talus is available as a free wallpaper image.
