The term that describes the lunar topsoil is "lunar soil". Lunar soil is the fine fraction of lunar regolith found on the surface of the Moon and contributes to the Moons tenuous atmosphere. It is composed of various types of particles including rock fragments, mono-mineralic fragments, and various kinds of glasses including agglutinate particles, volcanic and impact spherules. The thickness of the lunar regolith varies from about 5 m on the maria to about 10 m on the highlands. Although the term "lunar soil" is often used interchangeably with "lunar regolith", some have argued that the term "soil" is not correct because it is defined as having organic content. However, standard usage among lunar scientists tends to ignore that distinction.