Palisades Sill
Near Red River, New Mexico
Those dramatic vertical cliffs rising along the Cimarron River are the Palisades Sill, and they are a window deep into the earth's plumbing. Tens of millions of years ago, as the southern Rocky Mountains were heaving upward, molten rock forced its way sideways between layers of older stone and then cooled underground into a hard sheet of igneous rock.
Geologists call that kind of intrusion a sill. Over the ages the Cimarron River sliced down through the canyon and exposed the sill's edge, leaving these soaring fluted walls that look almost like a row of stone pillars or palisades. Studies have dated the rock to somewhere between roughly twenty-six and thirty-five million years old. The sheer faces tower over the highway, and the official scenic marker here lets travelers read the canyon's fiery origin.
