Canyonlands National Park in southeastern Utah both amazes and overwhelms the visitor. And well it should: it's been more than 300 million years in the making!
The foundation, so to speak, of Canyonlands was laid down during the Pennsylvanian geologic period that began about 320 million years ago. For 30 million years, ancient seas advanced and retreated leaving behind salts and other minerals. At the same time, darker shales eroded away from the nearby Uncompahgre Uplift and further built up the area. By the end of the Pennsylvanian period, nearly 3,000 feet of layered sediments had built up. Surprisingly, however, rock from this time is visible in only a few areas of the park.
The spectacular and colorful rock layers that are so prominent in Canyonlands today rest atop this foundation. Over the next 100 million years – spanning the Permian, Triassic and Jurassic geological periods – layers of sediment continued to build up. Ancient seas continued to advance and retreat, leaving behind distinctive, lighter colored sediments from erstwhile beaches and sand bars. One of the lighter-colored layers left near the end of the Permian is called White Rim Sandstone and, as we shall see, figures prominently in the creation of many of the park's most spectacular formations. During other times, darker, reddish-brown deposits eroded from nearby mountains. Today, these alternating light and dark layers are readily visible throughout Canyonlands, especially in The Needles area of the park.
During the Triassic period, which began about 250 million years ago, the area that is now the parched desert of Canyonlands was a broad river delta. Streams deposited a variety of shales, siltstones, mudstones and sandstones. Some forty or fifty millions years later, toward the end of the Triassic, the climate changed dramatically again and Canyonlands and much of Utah was a sand-filled desert with shifting dunes, much like the present-day Sahara. After another wet period, the sandy deserts returned during the Jurassic period, which began about 200 million years ago. For another 140 million years new layers continued to be deposited. Most of these later deposits, however, have already been lost to erosion in Canyonlands (though remain visible in other areas such as Arches and Bryce Canyon National Park).
The Canyonlands National Park we see today was carved out of this ancient layer cake of sediments by the Colorado and Green Rivers, which merge within the park. Over millions of years, the rivers and their seasonal tributaries cut through the layers while rain, wind and the freeze-thaw cycle went to work on the areas left behind. The result that we see today is a dramatic, two-thousand foot drop from the mesa top of the park's Island in the Sky area to the surface of the rivers. This drop takes place in two giant, thousand-foot steps. One step descends from the mesa top to a layer of White Rim Sandstone that because of its harder consistency resisted wind and rain erosion. The second step descends another thousand feet to where the Colorado and Green Rivers cut through even the more durable White Rim Sandstone. Most surprisingly, at least another vertical mile of rock strata that once lay atop even the highest points of Canyonlands has long since disappeared.
The park is divided into three main sections. The highest area, and the one that offers the most expansive views of the canyons below, is called Island in the Sky. From here, there are sweeping vistas of the Colorado and Green Rivers two thousand feet below. This area of the park also includes the dramatic Mesa Arch and Upheaval Dome, a geological formation that perplexed geologists for decades. The Island in the Sky is easily accessible by car and many of the most stunning overlooks are only a short walk from the paved road.
On the way to the Island in the Sky park entrance driving west from Moab, UT, one passes Dead Horse Point State Park, which is well worth a stop for its spectacular overlook of a gooseneck bend in the Colorado River. Although it's a separate park, Dead Horse Point is really part of the same geological formation as Canyonlands. (The point came by its rather gruesome name because horse thieves once used the mesa top to corral their stolen booty. It was easy to drive horses onto the point and trap them there with a fence across the narrowest part. Unfortunately, on at least one occasion, the trapped horses were neglected and died of thirst.)
About 75 miles south of Moab is the area of Canyonlands National Park known as The Needles. It lies to the east of the Colorado River. Several hiking trails in the area snake through fantastic, multi-colored rock spires, called "needles". Along the trails, one has a close-up view of the many layers of sediment left behind hundreds of millions of years ago. Here again, White Rim Sandstone plays a starring role. More resistant to erosion than the layers of softer sandstone beneath it, the White Rim Sandstone acts a protective cap that allows the rock spires to form. As erosion eats away the softer lower layers, a wide variety of forms are produced including spires (or needles), pillars, mushrooms and other shapes.
The third major area of Canyonlands, in the southwestern part of the park and west of the Colorado River, is called The Maze. This is the least accessible area of the park and entrance is gained only by foot, on horseback or with a 4WD vehicle. This area borders the Glen Canyon National Recreation Area, where the Colorado River leads into Lake Powell. Not being outfitted for a backcountry adventure, I didn't see The Maze and there are no photos of that area here.
During my early-May visit, Canyonlands National Park held yet another surprise – beautiful flowers. Although one does not normally associate the desert southwest with verdant vegetation, it does have its moments, most particularly in spring when the desert comes into bloom. In fact, I even experienced some rare rain during my visit (note the general lack of blue skies in the photos) that further encouraged desert flowers. The last few photos in the slide show above feature some of the desert's more showy plants: Claret Cup Cactus, Desert Primrose and Indian Paintbrush. And although it's not much to look at, Canyonlands also boasts large areas covered by "microbiotic crust" – a mixture of lichens, cyanobacteria (blue-green algae) and moss that can be easily mistaken for barren soil. But this delicate structure, which takes years to form, plays an important ecological role by capturing moisture and resisting soil erosion. Visitors who leave the marked trails can easily and unwittingly destroy the microbiotic crust and in a single step undo decades of patient growth (not to mention leaving areas vulnerable to erosion from wind and rain).