Daily Postcard: Sunrise through the trees, Valles Caldera National Preserve. The Valles Caldera is in the center and at the top of the Jemez Mountains. The 88,900-acre preserve encompasses almost all of the volcanic caldera created by a spectacular volcanic eruption about 1.25 million years ago. The caldera is dormant, but not extinct, and still displays signs of volcanic life with hot springs and boiling sulphuric acid fumaroles. Source: VCNP. Courtesy/VCNP