The Chisos Basin: The Only Park Containing an Entire Mountain Range

The Chisos Mountains are an island. Not a literal one, surrounded by water, but an ecological island surrounded by desert: a sky island, in the language of biogeographers, where the elevation creates a distinct climate and habitat system separated from the surrounding lowland desert by thousands of feet of vertical change.

The Chisos are the only mountain range in the United States entirely contained within a national park. Big Bend's eight hundred one thousand acres were drawn specifically to encompass the full range from summit to desert base. The basin you are in sits at five thousand four hundred feet, high enough that ponderosa pine and Douglas fir grow here, species that require precipitation and temperature ranges unavailable on the desert floor a mile below.

Black bear live in these mountains. Mountain lion patrol the ridgelines at night. The Colima warbler, a small gray-and-yellow bird, breeds nowhere else in the United States: the Chisos are its only nesting ground north of the Rio Grande. The basin's isolation has made it a refuge for species that cannot survive in the fragmented lower desert.

The geological record of the Chisos runs back about thirty five to forty four million years, when volcanic activity built these mountains from the desert floor. The rock formations visible from the Window pour-off, where the basin's water drains through a notch in the southern rim, show the layered record of that eruption sequence in cross-section.

At night, from five thousand four hundred feet, with the desert below invisible in the dark and the Milky Way visible without amplification, the basin produces the effect of being very far from everything else. The effect is accurate. You are.