K-T boundary

noun

: the transition between the Cretaceous and Tertiary periods of geologic time characterized by a mass extinction of many forms of life including the dinosaurs

also : a geologic stratum marking this boundary

Examples of K-T boundary in a Sentence

Recent Examples on the Web

Kring was foundational in confirming the role of the Chicxulub crater’s impact event in the K-T boundary mass extinction. —Anna Funk, Discover Magazine, 14 Nov. 2018

Word History

Etymology

K (alternative for C as abbreviation for Cretaceous) + Tertiary

First Known Use

1983, in the meaning defined above

Kids Definition

K-T boundary

noun

: the transition between the Cretaceous and Tertiary periods of geologic time marked especially by the extinction of the dinosaurs

also : a layer of rock marking this boundary