《徐霞客游记·滇游日记三十三》
峭壁有过，没有此种酥松的土质；流动的土石有过，无此等松散的岩石。
盖峭壁有之，无此苏即酥软而散土；流土有之，无此苏石。
I have encountered steep cliffs before, but I have never encountered such loose soil; I have encountered flowing soil and rocks, but I have never seen such loose rocks.