Elevations within Big Bend National Park range from 1,800 feet at the eastern end of Boquillas Canyon to 7,825 feet atop Emory Peak. These elevation changes produce an exceptional variety of microclimates, plants, animals, and scenic vistas.

At the heart of park lie the Chisos Mountains, a range born of fire during volcanic eruptions and igneous intrusions 40 - 60 million years ago then exposed by the incessant forces of erosion. Ascending the slopes of the Chisos, the thorns of the desert give way to evergreens like pinyon pine and juniper, and oak trees begin to appear. Some surprising species living at the very limit of their ranges can be found in the higher, moister areas, such as bigtooth maple, quaking aspen, and Douglas fir.

Although only 2% of the park is woodland, this area draws people like a magnet, especially in the summer, as daytime temperatures are usually about 20 degrees cooler than by the river. Here, in this mountain island surrounded by a desert sea, one can find flora and fauna unique to the Chihuahuan desert, and some unique to Big Bend.

Birdwatchers hope to gain a glimpse of the colima warbler, a bird that winters in Mexico and is seen in the US only in Big Bend. Mountain lions, black bears, and towering century plants also make the Chisos their home. Visitors to the Chisos are struck by the contrasts the mountains provide. Prickly pears and pine trees live side by side, and a snow-covered cactus is not an uncommon sight.

If the Chisos Mountains are the heart of Big Bend, then the desert floor is its soul. Ninety-eight percent of the park is desert, and, like the mountains, the desert is a land of contrasts. You can touch 400-million-year-old rocks with one hand and a day-old flower with the other, and temperatures can soar 50 degrees between dawn and midday.

Big Bend's desert landscape encompasses mesas, mountains, and dikes formed by volcanic activity; limestone ridges and cliffs formed 100 - 200 million years ago when shallow seas covered the area; and ever-changing arroyos that are dry most of the year, but subject to violent flash flooding during summer rains. Water is truly the architect of the desert, as its presence or absence determines the way the desert looks, its plant and animal life, and the way humans have been able to use it through time. The adaptations that allow creatures like the roadrunners, coyotes, or javelinas to survive here are no less than amazing, and even allow them to thrive. Think of the land not as burdened by its lack (or, in some months abundance) of water, but rather as blessed. It is this cycle of wet and dry, so unfamiliar to those from wetter climates, that makes possible the spectacular displays of bluebonnets, yucca blossoms, and other beloved wildflowers.

The one location where you can count on seeing water in Big Bend is along the Rio Grande, a riparian oasis that has been called the lifeblood of Big Bend. To drift through the majestic canyons of the Rio Grande with your oars touching two countries at the same time is to span time and space. Although the river, as the boundary between the United States and Mexico, looks like a solid line on the maps of the area, it is always changing, always going somewhere, and it takes us along on its current, opening our eyes to a panorama of towering cliffs, brilliant bird life, and grassy vegas or beaches.