Cretaceous-Tertiary extinction event

The Cretaceous-Tertiary (K-T or KT) extinction event, also known as the KT boundary, was a period of massive extinction of species, about 65.5 million years ago. It corresponds to the end of the Cretaceous Period and the beginning of the Tertiary Period. (K is the traditional abbreviation for the Cretaceous period. Cretaceous comes from the Latin for chalk, creta. The K comes from the German word for chalk kreide, or possible Greek kreta. The K is used so as to avoid confusion with the Carboniferous period which uses the letter C.)

Chicxulub crater

Main article: Chicxulub Crater

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One problem was that no known crater matched the event. This was not a lethal blow to the theory. Although the crater resulting from the impact would have been 150 to 200 kilometers in diameter, Earth's geological processes tend to hide or destroy craters over time. Still, finding a crater would have buttressed the "Alvarez hypothesis", as it came to be known. The discovery by Alan K. Hildebrand and Glen Penfield of a crater buried under Chicxulub in the Yucatan as well as various types of debris in North America and Haiti have lent credibility to this theory (see Chicxulub Crater). Most paleontologists now agree that an asteroid did hit the Earth 65 million years ago, but many dispute whether the impact was the sole cause of the extinctions.

Related Topics:
Chicxulub - Yucatan - Haiti - Chicxulub Crater

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