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Chicxulub crater and the ( K – T ) boundary
About 65 million years ago , an asteriod more than 6 miles in diameter , struck what is now the yucatan peninsula of mexico .
The impact created the chicxulub crater more than 180 milles wide , and caused a gigantic dust cloud .
The dust eventually settled as a layer of iridium-rich clay .
Now found with in sedimentary rock layers beneath the Atlantic and Pacific oceans .
And on most northern landmasses the dust cloud may have caused temperature to drop around the world this global cooling following the impact is linked to the extinction of dinosaurs and more than half of all plant and animal species .
Significant differences in the fossil record separate the crataceaus (K) period from the mesozonic era from the tertiary ( T ) period of the cenozonic era marking the K-T boundry .
The (K) stands for kreide,german for cretaceous .
Other events at this time , including huge lava eruptions in what is now india Peninsula caused atmospheric changes that may have contributed to the mass extinction