Karesansui base ground

Quick answer：

Karesansui, also known as dry landscape or Zen rock garden, is a form of Japanese garden that uses carefully arranged rocks, gravel, or sand to represent a natural landscape, typically a mountainous scene. The base ground, which serves as the foundation for this garden, is often level and consists of these materials to reflect the natural terrain. It is a traditional Japanese art that emphasizes minimalism and the beauty of nature.