411 REFERENCE · Wiktionary
K-T boundary
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English
Alternative forms
en K/T boundary
en KT boundary
Noun
en noun K-T boundary
The geological signature of the transition between the Cretaceous period and the Tertiary period 65.5 million years ago.This transition is marked worldwide by a layer of material that contains a high level of iridium.
See also
en K-T extinction event
en Geology