The sand in feng shui refers to

In geomantic omen, the small earth slope that can be seen on the ground of caves is called sand. ....., the end of the mountain, the end of the dragon (Shanqi), called the cave. ..... In the geography of the Three Rivers, the unlucky entrance or exit seen at the bottom of the cave in the vertical direction is changed from fierce water to auspicious water, and it is called water elimination on the basis of the four major exits and the eight overall situations. (to be exact, it's called xiaoshana water). ....., the four outlets of dragon water alternate with yin and yang, and the dragon flows down the river. If water comes and goes in the opposite direction, it is called pouring water.