Gravel separated Zen rock garden

Quick answer：

A Zen rock garden, also known as a karesansui, is a type of Japanese rock garden that uses natural stone arranged to symbolize mountains, islands, and other natural features. Gravel is commonly used to represent water, and it is often placed between the stones to create a raked surface, giving the impression of flowing water. The use of sand or gravel to separate the rocks in a Zen rock garden is a design element that adds to the aesthetic and thematic elements of the garden.