As sunrise begins to show the first light of day, hikers take their first steps through geological time in what is known as one of the Seven Wonders of the World. Here among the rocks of a magnificent mile deep gorge on the South Kaibab Trail along the South Rim of Grand Canyon National Park one starts a journey through time. Hikers step off onto the trail at an elevation of 7,250 feet (2,200 meters). The trail is steep, descending 4,860 feet (1,481 m) in just 6.3 miles (10.1 kilometers) to the Colorado River at the bottom of the canyon.
Here at the trailhead, the route to the Colorado River cuts through Kaibab Limestone, the youngest of the rock formations found in the Grand Canyon, having been laid down under shallow ancient seas some 270 million years ago toward the end of the Paleozoic Era. This is the grayish-white to cream-colored rock that park visitors stand on and hikers walk over when pushing off onto the trail toward their first destination, Cedar Ridge.
Cedar Ridge is 1.5 miles (2.4 km) from the rim and is a vertical drop into the canyon of 1,000 feet (305 m). Hikers pass through not only the 300-400-foot (90-100-m) layer of Kaibab Limestone but also the other top layers of canyon strata: the Toroweap Formation, Coconino Sandstone and Hermit Shale. Signage along the way points out the joining of the layers as the texture of the rock changes beneath the hiker's feet.
Cedar Ridge is located in the Hermit Shale strata at an elevation of 1,140 feet (350 m) and was deposited on a broad coastal plain laid down by freshwater streams some 280 million years ago. The thin layer made of iron oxide, silt and mud is over-saturated with the fossils of ferns, winged insects and tracks of small vertebrate animals. It is here at Cedar Ridge that the hiker first feels what it is like to truly be IN the Grand Canyon.
Just a half mile down the trail from Cedar Ridge is found the prominent geological landmark of the Kaibab Trail, O'Neil Butte. Located on a saddle of Red Wall Limestone, O'Neil Butte is named for the famous Arizona Rough Rider, Buckey O'Neil. Another mile down the trail sees our geological time traveler pass through the Supai Group strata and arrive at Skeleton Point. Here, 3 miles (5 km) from the trailhead and 2,000 feet (610 m) below the starting point, the Colorado River first comes into view. This is also the beginning of the strata known as Muav Limestone.
The Redwall Limestone found at the level of Skeleton Point is about 335 million years old and is possibly the most prominent rock layer found in the Canyon. Here are found 400-500-foot (120-150-m) cliffs that act as a natural barrier between the upper and inner region of the Grand Canyon. The deep reddish color is the result of iron oxides leeching that have stained the actual light beige and gray color of the rock. The Redwall Limestone is rich with fossils of clams, brachiopods, snails, fish and trilobites. Here too are found unique cave and arch formations that are a photographer's delight.
After Skeleton Point, the trail down through time begins a sharp decent through a series of switchbacks toward the canyon's inner gorge. For the next 1.5 mile (2.4 km) the trail descends 1,200 feet (370 m) and passes through strata of Muav Limestone, Bright Angel Shale and Tapeats Sandstone. Ancient seas between 515 million and 545 million years ago also laid these, the last of the Cambrian Period rock layers, down. They are all a part of a landscape known as the Tonto Group and fossils of ancient marine trilobites and brachiopods are found throughout the strata.
Our geological time traveler now enters the canyon's ancient Inner Gorge. The Inner Gorge is made up only of metamorphic and igneous rocks from the Precambrian time of about 2,000 million years ago. During this time thousands of feet of mud, ash, sand and silt were laid down in shallow basins. Some 1,700 million to 1,600 million years ago the pressure of plate tectonics heated and pressed these marine layers into the metamorphic rock that is now exposed in the Inner Gorge. There are no fossils found in these Vishnu Group layers of rocks. With each step downward, the Colorado River comes closer and closer and the famous Black Bridge comes more and more easily into view.
Vishnu Schist is the most common rock of these massive black strata of the inner gorge. Here too are found other schists, known as Brahma and Rama, which are a part of the Vishnu Group. Into these layers of schists are also found thick intrusions of magma and layers of igneous Zoroaster Granite and gneiss.
After walking 6.3 miles (10 km) and dropping 4,860 feet (1,480 m) in elevation our geological time-traveling hiker enters a short tunnel and emerges to walk across the Colorado River on the Black Bridge. Built in 1928, this bridge changed how humans would experience the Grand Canyon by opening the opportunity to "walk through time" to thousands each year. Most of the 122 tons of materials for the construction of the bridge were carried to the Colorado River by National Park Service mules. The 1-ton, 1.5-inch thick, 550-foot long suspension cables needed to span the great river were transported to the river by 42 Havasupai tribesmen, walking single file down the trail while carrying the cables on their shoulders.
The Colorado River , at an elevation of 2,400 feet( 730 m) is one of the great rivers of the world, traveling 1,450 miles (2,333 km) from its source at La Poudre Pass in Rocky Mountain National Park, Colorado, to its mouth on the Sea of Cortes in Mexico. The sediment that once colored the river red has been stopped behind the great dams that now slow the river, but adventurers still travel upon it as this group does while passing near Black Bridge.
The geological time traveler now turns north along the river and joins up with the Bright Angel Trail to travel up for 7.7 miles (12.4 km) and ascend 4,420 feet (1,347 m) to again stand on the South Rim. Following a natural break in the massive cliffs by the Bright Angel Fault, Native American people for millennia followed the passable cliffs to enter the Grand Canyon. In the early 1880s, Arizona business man Ralph Cameron extended and improved the ancient trail, opening the opportunity to travel through time to people all over the world. The trail was turned over to the National Park Service in 1928. Explorer John Wesley Powell first used the name Bright Angle Creek when he named a fresh water stream that continues today to flow into the Colorado River.
Bright Angel was one of the first names used to describe the many features of the Grand Canyon: Bright Angel Canyon, Bright Angel Camp, Bright Angel Point and, as seen here, Bright Angel Creek are all major features of the Grand Canyon. The source of the water for Bright Angel Creek is several large holes in the Redwall Limestone cliffs at a place known as Roaring Spring, so named for the sound of the gushing water coming from the canyon wall.
As the climb back up to the South Rim continues, our hiker must give way on the trail to other Colorado River visitors who have chosen their journey on the backs of reliable mules. Sauntering along the Bright Angel Trail, these sure-footed animals were first used in the Grand Canyon in the early 1920s. They have carried thousands of visitors from all around the world, including Theodore Roosevelt, past the geological formations of time into and out of the great canyon.
The journey back up the Bright Angel Trail leaves the cool, riparian zone of the Colorado River and quickly returns to the arid landscape found within the canyon. Here a beavertail cactus greets our traveler as the climb to the top continues.
A strenuous hike of 3.1 miles (5 km) from the Colorado River is a Cottonwood-shaded oasis first used by the ancient native people. Known as Indian Gardens, the welcoming rest stop along the trail is at an elevation of 3,875 feet (1,180 km) and 4.6 miles (7.4 km) from the South Rim. The trail to Indian Gardens was first built by the Havasupai people, and because of the perennial flow of a small creek, was used to grow summer crops.
A hike through this geological wonderland can be dangerous, and great preparation and caution should be taken. The National Park Services reminds travelers to hydrate and take scheduled rest stops. A quick change in the weather can result in flash flooding and rockslides. Being in an arid climate, heat is a common concern especially during the summer months.
Bright Angel Trail and the South Kaibab Trail are known as the two superhighways of the Grand Canyon because of the thousands of visitors who use these trails each year to walk through this amazing textbook of geological time. The many series of switchbacks found along both trails allow visitors to descend and ascend the steep canyon walls and truly experience firsthand the Grand Canyon.
Finally the 7.7-mile distance (12.4 km) from the Colorado River to the Bright Angel Trailhead is conquered and once again our exhausted hiker stands upon the Kaibab Limestone surface of the South Rim. After all the layers of geological time were traversed and after all the hours spent on the hot, dusty, winding trails are now over, the grateful hiker stands at the top of the Bright Angel Trail and gazes back down into the magnificent canyon from which she has just emerged, proclaiming now and forever for all to hear, "I hiked the Canyon!"