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Colorado’s arch park: Rattlesnake Canyon

Courtesy Thomas Holt WardCentennial Arch has a height of 120 feet and span of about 65 feet. Powerful, architectural columns support the elegant ribbon of stone.
Day hike west of Grand Junction offers bountiful formations

Rattlesnake Canyon cleaves the north flank of the Uncompahgre Plateau, plummeting 2,000 feet to the Colorado River at Horsethief Canyon. Rattlesnake contains one of the largest concentrations of natural arches in the United States; some say it ranks second only to Arches National Park. The rugged and demanding road to the trailhead, open April 15 through August 15, assures solitude. The hike is west of Grand Junction, within both the Black Ridge Canyons Wilderness (75,439 acres) and the McInnis Canyons National Conservation Area (123,430 acres), administered by the BLM.

Tackle both the Lower and Upper Rattlesnake trails in one day. The Lower Trail runs along the base of the arches. The Upper Trail parallels the Entrada Sandstone rim where you can peer down through the windows. Skilled canyoneers may connect the two trails via a steep friction pitch through Cedar Tree Arch.

The trailhead looks out over the Book Cliffs and the Colorado River meandering through the Grand Valley. At elevation 5,860 feet, the trailhead is the highpoint of the hike. Descend northwest while watching for abundant wildlife – deer, bighorn sheep, and mountain lion. Durango ornithologist John Bregar identified 20 bird species, including several prairie falcons.

Five distinctive geological formations are seen on the hike. The access road and trailhead rests on the Morrison Formation. The Jurassic sedimentary rock is a fertile source of dinosaur fossils. The Morrison overlies arch-forming Entrada Sandstone, the focus of this hike. The Entrada is held up by ledge-forming Kayenta Formation. Underlying the Kayenta is cliff-forming Wingate Sandstone. The floor of Rattlesnake Canyon is within the colorful, slope-forming Chinle Formation.

Courtesy of Thomas Holt WardHikers stand on the Entrada Sandstone rim overlooking Centennial Arch. The span embraces and contains a massive volume of hollowed-out space.

The Upper and Lower trails split half a mile into the hike. Turn right on the Lower Rattlesnake Arches Trail. The well-engineered path steps down through Entrada Sandstone. Reach a second signed junction at 0.7 mile. Turn left toward Lower Rattlesnake Arches to stay on the blue-line Lower Trail. For those taking the purple-line spur to Window Rock Tower, turn right toward the Pollock Bench Trailhead.

Window Rock Tower

The optional spur to Window Rock Tower is 1.1 miles roundtrip. Walk east on flat, Kayenta-red earth while scanning for arches in the cliffs above. Branch southeast on a well-trodden path at one mile. Unlike other arches highlighted in this post, Window Rock Tower (“South American Arch”) is an isolated fin arch, a stand-alone remnant separated from the Entrada rim.

Lower Trail

Return to the main trail and continue west. Sensuous, organic sandstone forms captivate in subtle shades of red blush and bisque. Blossoming wildflowers cast brilliant dots of color throughout the piñon-juniper woodland: milkvetch and buckwheat, rockcress and popcorn flower, Perky Sue, Indian paintbrush, phlox, wallflower, townsendia and scarlet gilia. Other common desert flora include sagebrush, rabbitbrush, snakeweed, prairie pricklypear and ephedra.

Round the corner into Rattlesnake Canyon at 2.9 miles. The entire series of arches are formed along the Entrada Sandstone cliff face. The Lower Trail rests on the Kayenta Formation at the contact with the Entrada.

Hole in the Bridge Arch appears right away. Its name references the secondary opening formed by a pothole in the main lintel. It is classified as an adult (most of the alcove roof has collapsed) cave arch with a span of 40 feet and opening height of 30 feet.

Debra Van Winegarden/Special to the HeraldAs hikers cross Hole in the Bridge Arch, they pause in turn to look down through the pothole perforating the lintel.

Companion perforation, "Leftside Arch," drops a shaft of light into a deep and dark cavity. The alcove entrance mounts up ever steeper. For those contemplating the passage through Cedar Tree Arch, have some fun and test the sticking power of your footfall.

Rattlesnake Canyon arches were formed and fashioned by erosion and weathering. The Natural Arch and Bridge Society defines a natural arch as, "a rock exposure that has a hole completely through it formed by the natural, selective removal of rock, leaving a relatively intact frame." The forces of erosion – gravity, wind, water, and ice –wear away and transport the rock. Weathering softens the rough edges of the rock in its original position through physical, chemical and biological processes.

Monumental and venerable, Centennial Arch has a height of 120 feet and span of about 65 feet. The arch is so old it is impossible to know whether it evolved from an alcove or pothole, but there is clear evidence of subsequent development. The cycles of erosion and the vagaries of weather have worked and reworked rock to fashion a testament to Earth's pursuit of beauty. Powerful, architectural columns support the elegant ribbon of stone.

Arches present in quick succession and the wonder of the canyon is ceaseless, enhanced by ever-evolving Entrada forms – stout towers, stacked alcoves, amphitheaters, and solution cavities. On close inspection the sandstone is composed of uniform, fine-grain sands, an indication it was eolian (wind-blown) in origin. Cross-bedding enhances subtle color banding.

Debra Van Winegarden/Special to the HeraldScaling to the base of Trap Arch was an irresistible draw for our adventurous lineup from Durango.

Trap Arch is a visually convoluted aperture tucked up high on the north wall of a small amphitheater. It was an irresistible draw for our adventurous lineup from Durango. Remember, it is riskier to go down than up, and an imperceptible change in slope angle can mean the difference between sticking and sliding.

Reach the End of Trail sign at about 4.1 miles where a beautiful view of Cedar Tree Arch awaits. The old pothole arch has an arc lintel spanning 76 feet and a semicircular opening height of 43 feet. Most hikers turn around here, return to the junction with the Upper Trail, and then walk the rim.

Through Cedar Tree Arch and Rim Walk

Climbers with experience on steep friction slopes may consider scaling two Class 4 pitches through the arch to reach the Entrada rim. Having a rope at the ready is recommended. A few toe holds gouged into the sandstone assist with the first incline.

One of the highlights of this hike is the easy-going rim walk to the northwest, paralleling the Upper Trail. There are literally no obstacles over the next mile. Meander all over while staying well away from the cliff edge. It's not always clear which surfaces are overhung.

Debra Van Winegarden/Special to the HeraldA few toe holds gouged into the sandstone assist as climbers approach the base of Cedar Tree Arch.

Please use good judgement when deciding whether to cross an arch. Viewing Centennial Arch from the rim is riveting and the yearning to fully experience the anomaly takes possession, but this arch is too delicate to risk crossing.

Upper Trail to Trailhead

Soon after passing Hole in the Bridge Arch, at about 5.5 miles come to the end of the promontory and stand on the flank of the Uncompahgre Uplift. About four million years ago, the Uncompahgre fault block began to lift an area from Fruita on the Colorado River to Montrose on the northwest margin of the San Juan Mountains, creating the Uncompahgre Plateau.

Locate the Upper Trail nearby. Hop on it or double back on the rim. Past Cedar Tree Arch, the trail leaves the rim and returns to the Upper and Lower trail junction. Retrace your steps half a mile southeast to the trailhead.

EDITOR’S NOTE: It is best to avoid this hike during the extreme heat of summer. A hike exposed under direct sunlight, target a cooler day for this trek.

http://debravanwinegarden.blogspot.com. Debra Van Winegarden is an explorer and freelance writer who lives in Durango.

From the Rattlesnake Arches Upper Trailhead, walk northwest on the red-line trail to the junction of the Upper and Lower trails. Descend north on the Lower, blue-line trail. Take the purple-line spur east to Window Rock Tower. Continue west on the Lower Trail and then curve southeast into Rattlesnake Canyon. At the end of the trail, climb through Cedar Tree Arch. Walk northwest on the black-line rim route. Return on the green-line Upper Trail. (Debra Van Winegarden/Special to the Herald)

Travel basics

Travel: Rattlesnake Canyon Upper Trailhead is accessed from Rim Rock Drive in the Colorado National Monument. 4WD with high clearance is required for the last few miles to the trailhead. (Alternatively, there is 2WD access to Rattlesnake Canyon from the Pollock Bench Trailhead but the hike is significantly longer.) Roughly halfway between the East and West gates of the Monument (6.5 miles east of the Visitor Center), turn west on Black Ridge Road and measure distance from there. The dirt road is impassable when wet. Turn right at 0.2 mile and enter McInnis Canyons NCA. At 1.5 miles, go left on Upper Black Ridge Road. Pass through an open gate at a cattle guard, 2.5 miles. This gate is locked during the closed period. At 4.7 miles, branch left at a Y. (Straight ahead, the road climbs to a dispersed camp at Point 6,883'.) At the next two splits, stay to the right. Descend steep switchbacks off the plateau. Park at road's end, 10.2 miles. No facilities.

Distance and Elevation Gain: 7.2 miles (includes Window Rock Tower); 600 feet of climbing. Out-and-back on the Lower and Upper trails is 7.4 miles.

Total Time: 4.5 to 6 hours

Difficulty: Trail, off-trail; navigation moderate; Two Class 4 friction pitches with exposure; carry plenty of water and hike on a cool day.

Reference: The Natural Arch and Bridge Society is a science-based, volunteer non-profit organization promoting the study and preservation of natural arches and bridges.

Maps: Mack, Colorado 7.5' USGS Quad; Trails Illustrated No. 208: Colorado National Monument, McInnis Canyons National Conservation Area