Eustacies

Part of speech: noun

Definitions

1. Periodic global changes in sea level caused by variations in the amount of water in the oceans or in the shape of ocean basins ; shifts in the worldwide average height of the seas relative to land terrain ; fluctuations in marine levels driven by geological or climatic factors
2. Global-scale rise and fall of sea surfaces due to factors like melting glaciers or tectonic alterations ; alterations in the average ocean water height across the planet's coasts ; changes in sea elevation resulting from both natural and environmental influences
3. Worldwide modifications in sea height relative to the continents as a result of glaciation cycles or ocean basin volume changes ; systematic variations in sea level affecting coastal and marine environments ; shifts in oceanic water levels on a planetary scale linked to climatic and geophysical processes

Etymology: "Eustacies" is the plural of "eustacy," a term for the global-scale change in sea level, rising or falling across the whole ocean rather than at one coastline. An eustacy is distinct from local changes caused by land sinking or lifting, since it alters the average height of water everywhere at once, whether through melting glaciers or shifts in the sea basins. The singular "eustacy" is a technical coinage built on Greek elements, and the plural simply follows the regular English pattern of adding "-ies" to a noun ending in "-y." Because the plural names several distinct sea-level events, it is the form geologists use when comparing episodes across the planet's history.

Synonyms: sea level changes, marine transgressions

Antonyms: regressions