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
Wallowa Mountains addition there are many older terranes between the batholith and basalt flows. The Wallowa Batholith is formed of granite from a magma upwelling in Late Jurassic and Early Cretaceous time (between 160 million and 120 million years ago). The placement of this rock caused uplift of the surface, which at the time was tropical sea. This is evident from the slate, quartzite, and marble present in the mountains, which come from metamorphism of the sedimentary deposits of oceans during the Triassic. At the center of the Batholith are granodioritic rocks, while the outer limits of the range are tonalitic. The