Cretaceous–Paleogene boundary Cretaceous–Paleogene boundary The Cretaceous–Paleogene (K–Pg) boundary, formerly known as the Cretaceous–Tertiary (K-T) boundary, is a geological signature, usually a thin band of rock. "K", the first letter of the German word "Kreide" (chalk), is the traditional abbreviation for the Cretaceous Period and "Pg" is the abbreviation for the Paleogene Period. The K–Pg boundary marks the end of the Cretaceous Period, the last period of the Mesozoic Era, and marks the beginning of the Paleogene Period, the first period of the Cenozoic Era. Its age is usually estimated at around 66 Ma (million years ago), with radiometric dating yielding a more
Lake Parime the Takutu Basin or the Takutu Formation, dates back to the late Paleozoic, roughly 250 million years ago, and the basin connected with the Atlantic via the Takutu Graben. The geologic history of the Takutu Graben is characterized by one phase of volcanic activity and three depositional phases of sedimentary rocks. Rifting (due to divergent tectonic plate movements) occurred in "a lake or delta environment" in the Late Triassic to Early Jurassic periods, between 200 million and one hundred and fifty million years ago. Starting around 66,000 years ago, sea level rise and more humid conditions created flooded zones north