Regolith

Part of speech: noun

Pronunciation: /ˈɹɛɡəlɪθ/

Definitions

1. A surface layer composed of unconsolidated rock and mineral particles that rests atop solid bedrock represents the remnants of geological processes
2. An accumulation of weathered fragments, dust, and debris found on the surfaces of moons and planets signifies a significant aspect of celestial geology
3. A loose covering of broken rock and soil debris lying above solid rock on the surface of Earth or other planets

Etymology: The word was coined in 1897 by the American geologist George P. Merrill, who needed a name for the loose layer of broken rock and dust that blankets the bedrock beneath the surface of the Earth. He built it from Greek: "rhêgos" meant a rug or blanket, and "lithos" meant stone. The image is of a stony covering laid over solid ground, which is exactly what the layer looks like in the field. The coinage is an irregular formation, meaning it does not follow a standard pattern for combining Greek roots. Merrill was not describing an ancient or classical concept, so the Greek elements serve only as building blocks for a modern scientific term. The word was later taken up by planetary scientists, who applied it to the debris covering the Moon and other bodies, and it now names that surface layer wherever it is found in the Solar System.