This period was precede by a period that saw the formation of the Chalk Group in northwestern Europe, and it was succeeded by a period that saw the completion of the breakup of Gondwana and the collision of the Indian Plate with Asia. Though the Signor-Lipps effect, exemplified by the disappearance of the cephalapod Ammonite, makes the duration of this period difficult to determine, evidence for this event was provided by Walter and Luis (*) Alvarez in the form of an extremely high level of iridium at this event's namesake sedimentary boundary. The Chicxulub Crater is 
This period was precede by a period that saw the formation of the Chalk Group in northwestern Europe, and it was succeeded by a period that saw the completion of the breakup of Gondwana and the collision of the Indian Plate with Asia. Though the Signor-Lipps effect, exemplified by the disappearance of the cephalapod Ammonite, makes the duration of this period difficult to determine, evidence for this event was provided by Walter and Luis (*) Alvarez in the form of an extremely high level of iridium at this event's namesake sedimentary boundary. The Chicxulub Crater is seen as the most likely remnant of the cause of, FTP, what extinction event of 65 million years ago that killed the dinosaurs?
This period was precede by a period that saw the formation of the Chalk Group in northwestern Europe, and it was succeeded by a period that saw the completion of the breakup of Gondwana and the collision of the Indian Plate with Asia.
{Cretaceous-Tertiary extinction} event (accept {K-T extinction} or {K- Pg extinction}; accept Paleogene or Tertiary before "breakup")