Planetary Surface Composition

'Planetary Surface Composition' is the official term for the soil of a planetary surface. The Planetary Surface Composition Chart is a list of various soils that a planet may contain. Some planets have no more than one or two soil types, while some have several more. Soil types are a significant factor in the formation and maintenance of biomes/ecosystems. Base soils refer to soil types that are the most commonly occurring, as they are found on every existing planet in the universe to varying extents; base soils include sand, clay, dirt, chalk, and gravel. There are also other soil types based on the natural or artificial mixture of base soils such as silt and loam. Peat is a surface soil that is naturally formed from decayed plant and fungal matter, though there is no known planet where peat occurs on a worldwide scale. The term 'terrestrial planet' refers to a world on which various different soils can be found. While there are a limited number of terms referred to soil types, each soil type comprises of thousands to millions of subsoils (for example, Geonosian sand is different in texture than Tatooinian sand, though both are considered forms of sand).