What a Sky Island Is
A sky island is a mountain range that rises sharply from a surrounding desert or grassland, so that its cooler, wetter upper slopes are separated from other high country by a “sea” of hot lowland. The term is used by ecologists and has come into common use for the isolated ranges of southeastern Arizona, southwestern New Mexico and northern Mexico, a region often called the Madrean Sky Islands. The pattern comes from Basin and Range geology, in which crustal stretching left long valleys between steep mountain blocks.
Examples in or near Apache country include the Chiricahua, Dragoon, Huachuca, Pinaleno and Peloncillo ranges in Arizona, and a number of ranges in New Mexico, as well as ranges in the Sierra Madre of northern Mexico. Each has its own character, and visitors sometimes find it striking that a desert hike can lead within hours to pine and fir forest.
Why Elevation Matters
On a tall mountain, temperature falls and rainfall tends to rise with elevation. A range can therefore hold several zones, from desert scrub at the base to grassland, oak woodland, pine forest and, on some peaks, higher forest. Each zone has different plants and animals. A traveler who can move up or down the slopes has access to many more resources than one who stays in a single zone.
For people who followed the ripening of plants through the year, this was a significant advantage. Agave and cactus fruits grow at lower elevations, acorns and pinyon nuts in the middle slopes, and cooler forest offered relief in summer and wood for fuel. The general pattern of acorn and pinon gathering shows up in many parts of the Southwest, and sky island slopes were a natural place for it.
Water, Game and Shelter
Mountain ranges catch rain and snow and release it slowly through springs and canyon streams, and in dry country those springs were places of great importance. Deer, and in some areas other game, lived in the oak and pine zones, so Apache hunting often focused on the mountains. Rugged canyons, rock shelters and good views also made ranges defensible and useful for concealment.
Because the basins between ranges were crossed by long, dry stretches, travelers often planned journeys from one water source to the next. Knowing the mountains in detail, including springs, trails, passes and landmarks, was a form of expertise handed down in families, and it explains the degree of local knowledge that outsiders, including soldiers, often did not have.
Mountains and Chiricahua History
Several sky island ranges are strongly tied to Chiricahua history. The Chiricahua and Dragoon Mountains of southeastern Arizona, and the ranges of southwestern New Mexico and northern Mexico, lay within the territories of Chiricahua groups such as the Chokonen, Chihenne, Bedonkohe and Nednhi. These bands are described in more detail in other articles, and the historical conflict of the nineteenth century, including the Apache Wars, took place partly in this mountain-and-basin country.
Officers in the nineteenth-century army often described the mountains as “strongholds.” That language reflects an outsider’s view, and it is more accurate to say that these were homelands in which families lived, hunted and gathered, and where they knew the ground much better than newcomers. Spanish and Mexican presidios and, later, United States forts were placed to control passes and water in this terrain, a pattern seen at Apache Pass.
Sacred and Significant Mountains
Many Apache nations regard certain mountains as sacred. One example that is well documented publicly is Mount Graham in the Pinaleno Mountains, known in Apache as Dzil Nchaa Si An, which is important to the San Carlos Apache. Construction of telescopes on the summit has been contested for decades, and the dispute is an example of how Apache sacred mountains and present-day land management can collide. The details of what makes a mountain sacred are not always shared with outsiders, and visitors should not press for them.
Sky Islands Today
Many sky island ranges are now national forests, wilderness areas or parks, and others lie within reservations or on private land. They are valued by scientists for their biodiversity, because isolated mountains can shelter plants and animals that are found in few other places. Climate change and drought are matters of concern for these ecosystems, though predictions should be treated cautiously.
If you visit, remember that access and rules depend on who manages the land. Check with the relevant agency or nation, and keep in mind that you may be in a place of historical or spiritual significance to Apache communities even if no sign says so.