1. General term for the layer of unconsolidated (non-cemented), weathered material, including rock fragments, mineral grains, and all other superficial deposits, that rests on unaltered, solid bedrock. It reaches its maximum development in the humid tropics, where depths of several hundreds of metres of weathered rock are found. Its lower limit is the weathering front. Soil is regolith that often contains organic material and is able to support rooted plants. Compare saprolite.
2. The continuous layer of incoherent fragmental material, produced by meteorite impact, that typically forms the surface blanket on planets, satellites, and asteroids where the atmosphere is thin or lacking. The classic example is the lunar regolith, typically several metres thick, with components ranging from metre-sized blocks to micron-sized dust and glass particles.