Clastics

Part of speech: noun

Definitions

1. Materials composed of fragments or broken pieces of rock or minerals
2. Sedimentary rocks formed from the accumulation of clastic particles
3. A category of geological formations characterized by the presence of clastic sedimentary textures and structures

Etymology: "Clastics" is the plural of "clastic", so its history is that of the adjective. The root is the Ancient Greek "klastós", meaning "broken in pieces", which comes from the verb "kláō", "to break". Adding the suffix "-ic" produced the adjective, and the same Greek stem gives English words like "iconoclast", a breaker of sacred images. Geologists use "clastic" for rocks and sediments built from fragments of earlier rock, so a sandstone is clastic because its grains are broken remnants of older stone. "Clastics" therefore names the whole group of such rocks, formed when those broken fragments accumulate and harden over time.