January 13, 2021 448 PM
I’m on island time.
I live, work and play on an island in Far West Texas. I’m being serious. But to believe that, you’ll need a flexible definition of what an “island” is. Discard the textbook geography definition of a piece of land surrounded by water. Just a quick glance out here shows there’s plenty of land but not much water. We’re in the desert. Well, kinda.
Situated at an elevation of almost 4900 feet above sea level, I reside in the small town of Fort Davis, the highest town and highest county seat in Texas. Zooming out a bit, we sit just below the elevation of Denver (5280 feet) which is proudly known as the Mile High City. Sharing similar landscapes to a state in the heart of the lower Rockies, the Davis Mountains region has been referred to as the Colorado of Texas. But an island?
In one of my pre-pandemic ranger programs, which I call a sky island party, I would pass out flower leis to park visitors, playing up this notion that we’re on an island. Most people went along with it, but some of the men, not so much. Groups of out-of-towners would meet me on top of Skyline Drive Scenic Overlook in Davis Mountains State Park where I’d try to convince them that we were on an island. After a quick glance across the landscape, I could tell by their looks of skepticism that I had some persuading to do.
The easiest way for me to do this is with a satellite image of the Davis Mountains region. From thousands of feet above, it’s easy to see a mountainous pocket of green surrounded by an “ocean” of arid sandy colors. So it’s not that we’re surrounded by water, but by desert: the Chihuahuan Desert, the largest desert in North America.
But with our elevation, we rise above the desert and into the sky, as it were. And that is why the Davis Mountains are considered a “sky island.” From the state park looking west about 15 miles toward Mount Livermore, we can make out the densely forested higher elevations almost 3000 feet above us. But down onto the vast rolling grasslands of the Marfa plateau to the south where soaptree yuccas stand amid seas of golden grasses, I tell my visitors, “Here in the park, it’s like we’re on the beach, on the edge of this sky island.” But to their mild disappointment, there’s no tiki bar or luau to be found.
In short, a sky island is a biogeographical term coined to describe a higher, cooler, wetter mountain oasis completely surrounded by a lower, warmer and drier desert region. There are more than 20 sky island regions in the United States, all of them occurring in the western half of the country. And Texas has at least three notable sky islands: the Davis Mountains, occupying the center of the Trans-Pecos region; the Guadalupe Mountains, 100 miles to the north; and the Chisos Mountains, 100 miles to the south.
Comprising the three highest mountain ranges in our state, these islands in the sky have become some of my favorite places on earth. Whether it’s in the Davis, the Guads, or the Chisos, I love being on island time in Far West Texas.
So how did these islands get here? We can approach this answer in two ways: geology and climate, both of which are inseparably connected. I’m no geologist, but simply put, the Chisos and Davis Mountains were born of different but similar violent super-hot volcanic events some 35 million years ago. Along the Rio Grande rift, all kinds of volcanic uplift took place creating higher landmasses, followed by millions of years of erosion, leaving us today with mountains and canyons and deposits of volcanic soils below. The Guadalupes, on the other hand, are the eroded remains of an ancient fossil reef that was slowly lifted upward by tectonic compression, now revealing limestone rocks that were once living organisms in the ocean.
Now if I had a satellite image from 20,000 years ago during earth’s most recent ice age, Far West Texas wouldn’t look like it does today. There was no desert here then, instead a woodland and forested region with junipers, oaks and pines where grasslands and desert scrub are found today. When the climate began warming and drying, the Chihuahuan Desert began to form and spread out some 8,000 years ago, beginning in the lower, warmer and drier elevations. Slowly the trees died off and gave way to drought-resilient grasses and smaller, more prickly vegetation.
But the desert couldn’t fully reach the higher elevations where life there is buffered by cooler and wetter conditions. These sky island elevations have become known as “refugia,” allowing pockets of ice-age life to continue to survive. Along with other unique ice-age species, stands of Douglas firs, towering ponderosa pines, hearty pinyon pines, lush and eloquent Texas madrones, and even quaking aspen groves can still be found among Texas’ sky islands today. Little splashes of Colorado in Far West Texas.
Each year Fort Davis hosts a July 4th celebration dubbed “The Coolest Fourth.” We’re known for having some of the mildest summers in Texas, with temperatures rarely, if ever, getting into triple digits. Our hottest month, June, has an average high of 89 degrees –– not bad for the edge of the desert. And even on the hottest days of the year, the overnight low has always gotten down into at least the 60s every summer night I’ve spent here. On this island, we’re practically guaranteed nice, cool summer mornings. Of course things are undeniably warming due to climate change, but for now I’ll take it.
So what is it that gifts us with these cooler temperatures? It’s the elevation. Something every pilot knows is that for every 1000 feet gained above sea level, we can expect the temperature to decrease by about 5 degrees F. So I’ll pose to my sky island party guests a math question: Let’s assume for every 1000 feet gained, the temperature decreases by 5 degrees F. And say we’re climbing a big mountain from 1000 feet up to 6000 feet, and there’s a forecasted high of 75 degrees where we are. What will the high temperature be at the top, and should you pack a jacket for that hike? Answer: 50 degrees, and yes, you’d better pack a jacket.
The reason for cooler temperatures in higher elevations is surprisingly simple. The air in our atmosphere, which is made up of invisible particles of nitrogen, oxygen, carbon dioxide and other gases, we tend to think of as equally distributed –– just floating around. But these particles have mass, and mass is subject to gravity. So these air particles sink down and are more compressed at lower elevations, thus trapping the sun’s radiant heat like blankets. But as we climb up, these particles become less and less compacted, more spread out and increasingly less able to trap and hold heat, and voilà: higher elevations have cooler temps. And for tourists coming from, say, the coastal plains of Houston, this means less oxygen, too, which can take some getting used to.
The rainfall these sky islands receive is in large part thanks to our raised land masses. Whenever an invisible, but warm, moist air mass is on a collision course with the mountains, the mountains always win. So this moist air is pushed up, causing it to cool, condense and form clouds. Some of these clouds continue to grow into thunderstorms, dropping rain on the mountains that created them. In the summertime, it’s a beautiful thing to witness the sudden growth of thunderstorms during rainy season afternoons, from what started as a cloudless blue sky morning.
And it’s these cooler temps and rain events that allow our sky island woodlands and forests to flourish. When I get the chance to hike among the towering ponderosa pines in the Davis Mountains Preserve, I’m transported from Far West Texas to New Mexico and Colorado. I’m in the heart of the sky island, and in some of the densely forested pockets up there, it feels like a million miles from the desert.
Several species of wildlife love it up there too. For instance, the highest concentrations of black bears and mountain lions in Texas can be found in these resource-rich sky islands. We can share the trails with some truly impressive megafauna, where there’s more food, more water, and more protective cover.
And throughout our history, humans have been drawn to these sky islands. Notably the Mescalero Apaches were known to inhabit and thrive in several of the sky islands of the Southwest, including Texas’ sky islands, where there was always water, always food, and if it got too cold up in the mountains, all they had to do was descend to lower elevations. True sky island dwellers.
Today the secret’s out. Our sky islands have become some of the most popular places to visit and explore in the state. Simply put, they hold the best and highest concentration of hiking and outdoor recreation opportunities that Texas offers. And thankfully, two of our state’s three sky islands are located in national parks (with northern reaches of the Guadalupe range in New Mexico overseen by the National Forest Service), and that means we have access to these amazing places. And some 33,000 acres comprising the heart of the Davis Mountains sky island is owned and protected by the Nature Conservancy of Texas, which, withstanding the season of this pandemic, will generously allow chances to explore their beautiful property at least a handful of weekends a year.
On so many of my days off during this past year, day hikes, backpacks and trail runs in our two national park sky islands have restored my sanity. Several weekends when both parks were open, I’d check the weather and decide whether to head north to the Guads, or south to the Chisos. Uh oh, windy cold front’s gonna be hitting the Guads. Better head south. Or, Ooh, looking like a rainy weekend in the Chisos but blue skies in the Guads. I know where I’m goin’. Then I’d grab the appropriate trail map and start plotting my next adventure. One weekend, my sky island choice was decided on a coin toss.
Our sky islands are arguably the geographic backbone of tourism in our region. They make the drives scenic, the hikes epic, the trees tall, the temperatures moderate, and the wildlife happy. Rising up from the desert, they reveal not just that Texas has mountains, but stunningly beautiful, prominent, forested mountains. They are, in short, what made me fall in love with this part of Texas.
But these sky islands that I’ve come to love are fragile ecosystems, incredibly vulnerable to drought and wildfire. Desertification has been slowly creeping up into these islands for the past 10,000 or so years, and human-wrought climate change is only accelerating that trend. Given the incredibly dry season we’re in this year, it’s all the more important to mind any source of fire we could be responsible for out here, from cigarette butts to dragging chains to hot catalytic converters parked in tall grass.
So let’s continue to enjoy and care for our sky islands. These inspiring mountain ranges hold some of the very best natural resources our state offers, and are vital to the identity and experience of Far West Texas. And personally, I’m enjoying my time on these islands, and I still have a lot of exploring to do.
Until next time friends, keep walking on the wild side.