The Piedra Lumbre Formation is a geologic formation that crops out in the Picuris Mountains of northern New Mexico. Detrital zircon geochronology yields a maximum age of 1475 million years, corresponding to the Calymmian period.
Outcrop of Piedra Lumbre Formation along highway from Dixon to Picuris Pueblo, New Mexico, USA
Piedra Lumbre Formation, upper left, in contact with thinner beds of Pilar Formation, lower right
The Pilar Formation is a geologic formation that crops out in the Picuris Mountains of northern New Mexico. It has a radiometric age of 1488 ± 6 million years, corresponding to the Calymmian period.
Pilar Formation carbonaceous phyllite beds near Pilar, New Mexico.
Pilar Formation exposures on Arroyo del Plomo
Outcrop of Pilar Formation showing metatuff beds (white layers)
Sample of carbonaceous phyllite from the Pilar Formation