The Puye quadrangle covers an area on the eastern flank of the Jemez Mountains, north of Los Alamos and west of Espanola, New Mexico. Most of the quadrangle consists of a dissected plateau that was formed on the resistant caprock of the Bandelier Tuff, which was erupted from the Valles caldera approximately 1 to 2 million years ago. Within the canyons of the east-flowing streams that eroded this volcanic tableland, Miocene and Pliocene fluvial deposits of the Puye Formation and Santa Fe Group are exposed beneath the Bandelier Tuff. These older units preserve sand and gravel that were deposited by streams and debris flows flowing from source areas located mostly north and northeast of the Puye quadrangle. The landscape of the southeastern part of the quadrangle is dominated by the valley of the modern Rio Grande, and by remnants of piedmont-slope and river-terrace deposits that formed during various stages of incision of the Rio Grande drainage on the landscape. Landslide deposits are common along the steep canyon walls where broad tracts of the massive caprock units have slumped toward the canyons on zones of weakness in underlying strata, particularly on silt/clay-rich lacustrine beds within the Puye Formation.
