Rock, sand and gravel: These surfaces are highly durable and can tolerate repeated trampling and scuffing. (However, lichens that grow on rocks are vulnerable to repeated scuffing).

• 岩石,沙子和碎石路:这些地表有高度的耐久力,能忍受重复的践踏和擦磨(然而,生长在岩石的青苔却很脆弱经不起重复的擦磨)