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Must-See HAPPENINGS May 2016

Upheaval Dome Overlook Trail
by Laurie Schmidt

Ranchers and early settlers in the Canyonlands region most certainly stumbled upon many interesting sites and landforms as they explored the area. But the first folks to find themselves at the rim of Upheaval Dome must have come to a jolting halt. Smack dab in the middle of all the sandstone rock layers is a huge crater about three miles wide. In the center of this hole in the Earth’s surface is a jumble of rock and debris that’s been pushed upward to form a circular structure known as a dome.

In geologic terms, Upheaval Dome is what’s known as an anomaly—a feature that deviates from the other rock patterns and structures in the surrounding area. Look around and notice the layer-cake structure of rock formations that were uniformly exposed as the Colorado and Green Rivers cut through the flat mesa top. Suddenly, this geologic pattern is disrupted at Upheaval Dome, and rock layers that were once buried about a mile underground are now exposed at the surface in the core of the dome.

Upheaval Dome Overlook Trail

The trail to the Upheaval Dome viewpoint is really a two-part hike, although you can choose to do only the first section if you’re short on time. The hike begins at the parking/picnic area, and after just a short distance you’ll reach a spur trail to the Syncline Loop Trail. You’ll want to bypass this turnoff and continue straight to the First Overlook, which you’ll reach in less than half a mile. Although the trail is short, it does have some rocky sections. During summer months take plenty of water, as there is little to no shade on this hike.

I highly recommend continuing on to the Second Overlook if you have time. Although it adds another mile to your total hiking distance, it offers different perspectives of the crater, and you’re likely to have the viewpoint there all to yourself. The trail to the Second Overlook ends at a steel fence that provides the only barrier between you and a sheer drop-off. If you decide to wander away from this overlook area, explore cautiously and hang on tightly to the kiddies in your group.

A Tale of Two Theories
Upheaval Dome was mapped back in the 1950s by American geologist Eugene Shoemaker, one of the founders of planetary science. Over the next several decades, geologists debated over two theories about how the structure was formed. Each theory had its turn at being “in vogue” at various times, depending on which side currently had the most convincing research findings.

According to the first theory, the structure is an eroded impact crater, which resulted from a meteorite impact that struck the Earth millions of years ago during the Jurassic Period (yep—dinosaur times). Based on the size of the crater, scientists believe the meteorite was 500-1,000 feet in diameter. The explosion that would have resulted from such a large impact caused the rocks at the bottom of the crater to push upward to fill in the hole left by the blast.

The name Upheaval Dome actually comes from the other possible explanation for the crater’s origin: the salt dome theory. Millions of years ago, the entire Colorado Plateau region was covered by an ancient, shallow sea. Seas, of course, contain salt water, and as the area’s climate became drier, the seas dried up and left behind a thick layer of salt. As sediment accumulated over millions of years, the heavy weight of all that rock squeezed the less dense salt layer upward (think of pushing a cement brick into a pile of dough), where it intruded into the existing rock layers. The fact that salt domes are found throughout the area lends support to this theory, but its weakness is that it doesn’t really account for the large crater.

In 2008, an “Aha!” moment occurred when a team of German researchers discovered “shocked quartz” in the Kayenta Formation, the brown-colored layer you see around the rim of the crater just below the light-colored rock. Shocked quartz consists of individual grains of sand that have fracture patterns in them—patterns that aren’t naturally found in sand and can only form as a result of an impact event or an atomic blast. As a result of this finding, the impact theory is widely accepted today as the correct one.

Hiking Distance (round-trip): .8 mile to First Overlook; 1.8 miles to Second Overlook
Difficulty: Moderate
Cautions: High temperatures during summer; steep drop-offs
Getting There From Moab: Drive north on Hwy 191 for 11 miles. Turn left on State Route 313 and drive 21.5 miles to the Canyonlands National Park visitor center. Continue straight on the main park road (Grandview Point Road) for 6.3 miles. Turn right on Upheaval Dome Road and drive 4.7 miles to the Upheaval Dome parking and picnic area.


 
 
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