Eustacy

Part of speech: noun

Definitions

1. The global or regional changes in sea level resulting from variations in the amount of water in the oceans or changes in ocean basin capacity, especially due to geological or climatic factors
2. Fluctuations in ocean water levels that occur worldwide or over large regions, caused by shifts in ice volume, tectonic activity, or other long-term environmental processes
3. Variations in the height of sea surfaces on a global or large-scale basis, influenced by natural changes such as glaciation, thermal expansion, or seafloor spreading through geological time

Etymology: "Eustasy" is a geology term for global changes in sea level, and its shape is easy to read once you see the parts. The Greek prefix "eû" means "well" or "good," and "stásis" means "standing" or "a state of being set in place." Together, "eustatic" describes a sea level that stands steadily at one height across the globe, as opposed to a level that rises or falls locally because of land movement. The noun came by back-formation: someone took "eustatic," which had been borrowed from German "eustatische," and treated its ending "-atic" as if it were an adjectival suffix to strip off, then added the noun ending "-y" to the remainder. The result, "eustasy," names the phenomenon itself. Its spelling variant "eustacy" follows the same pattern and means the same thing.

Synonyms: sea level change, marine transgression, marine regression, global sea level variation

Antonyms: INVALID