D defs.my
Entry 1 sense Webster, 1913

Cretaceous-Tertiary boundary

/(krē̇*tā"shŭs)/ · Cre·ta·ceous-Tert·i·ar·y boun·da·ry · IPA
01 n. a thin layer of geologic deposits, of varying thickness in different parts of the world, found between the geological strata identified as …
  1. 1.
    a thin layer of geologic deposits, of varying thickness in different parts of the world, found between the geological strata identified as Cretaceous and the strata above, identified as Tertiary; also, the time point or period marking the boundary between the Cretaceous and Tertiary periods.
Syn. K/T boundary.