|Today we visited Arches National Park. Arches NP is known for preserving over 2000 natural sandstone arches, including the world-famous Delicate Arch (seen on the Utah license plate), in addition to a variety of unique geological resources and formations. The park is located just outside of Moab, Utah, and is 76,679 acres in area. We started our day at the visitor's center viewing the 15 minute orientation film and viewing the exhibits. We decided to rent the self-guided audio tour for $5 to go along with the booklet we were given. That was a great decision, it certainly made our drive today more informative & enjoyable. We soon realized that you can see a lot from a car but you really need to walk too.
We learned that water, ice, extreme temperatures and underground salt movement are responsible for the sculptured rock scenery of Arches National Park. On clear days with blue skies, it is hard to imagine such violent forces, or the 100 million years of erosion that created this land that boasts the greatest density of natural arches in the world. The more than 2,000 cataloged arches range in size from a three-foot opening, the minimum considered an arch, to the longest one, Landscape Arch, which measures 306 feet from base to base. New arches are being formed and old ones are being destroyed. Erosion and weathering are relatively slow but are relentlessly creating dynamic landforms that gradually change through time. Occasionally change occurs more dramatically. In 1991 a slab of rock about 60 feet long, 11 feet wide and 4 feet thick fell from the underside of Landscape Arch, leaving behind an even thinner ribbon of rock. Delicate Arch, an isolated remnant of a bygone fin, stands on the brink of a canyon, with the dramatic La Sal Mountains for a backdrop. Towering spires, pinnacles and balanced rocks perched atop seemingly inadequate bases vie with the arches as scenic spectacles.
The park lies atop an underground salt bed, which is basically responsible for the arches and spires, balanced rocks, sandstone fins and eroded monoliths that make the area a sightseer's Mecca. Thousands of feet thick in places, this salt bed was deposited across the Colorado Plateau some 300 million years ago when a sea flowed in the region and eventually evaporated. Over millions of years, the salt bed was covered with residue from floods and winds and the oceans that came and went at intervals. Much of this debris was compressed into rock. At one time this overlying layer of rock may have been more than a mile thick.
Salt under pressure is unstable and the salt bed below Arches was no match for the weight of this thick cover of rock. Under such pressure, the salt layer shifted, buckled, liquefied and repositioned itself, thrusting the rock layers upward into domes. Whole sections dropped into the cavities.
Faults deep in the Earth contributed to the instability on the surface. The result of one such 2,500-foot displacement, the Moab Fault, is seen from the visitor center. This movement also produced vertical cracks that later contributed to the development of arches. As this subsurface movement of salt shaped the Earth, surface erosion stripped away the younger rock layers. Except for isolated remnants, the major formations visible in the park today are the salmon-colored Entrada Sandstone, in which most of the arches form, and the buff-colored Navajo Sandstone. These are visible in layer cake fashion throughout most of the park. Over time water seeped into the superficial cracks, joints and folds of these layers. Ice formed in the fissures, expanding and putting pressure on surrounding rock, breaking off bits and pieces.
Winds later cleared out the loose particles. A series of free-standing fins remained. Wind and water attacked these fins until, in some, the cementing material gave way and chunks of rock tumbled out. Many damaged fins collapsed. Others, with the right degree of hardness and balance, survived despite their missing sections. These became the famous arches. Pothole arches form by chemical weathering as water collects in natural depressions and eventually cuts through to the layer below. This is the geologic story of Arches - probably. The evidence is largely circumstantial!
One nice thing about Arches is that "easy" doesn't mean "boring," at least as far as the scenery is concerned. The Balanced Rock Loop is a short jaunt around the base of a fragile and highly improbable geological rarity. A slightly longer walk to the Windows takes you to two massive sandstone portals you can climb through, plus Turret Arch as a bonus. After our hike to Windows we took a short break & enjoyed our picnic lunch as we watched folks climb about on the Double Arch. We passed taking the hike here as we really needed a break & wanted to conserve our energy for a later moderate hike.
The moderate hikes in the park are a little longer and a little steeper. Park Avenue is a one-mile (one way) walk through a deep canyon to the Courthouse Towers, an amazing set of red-rock spires shooting up from the earth. The Tower Arch hike is a longer meander through rocks and dunes to Tower Arch, which if you didn't know better you'd think was built for the set of a sci-fi movie.
Owing particularly to the rugged desert landscape, the difficult hikes in Arches are just that: steep, dry, and demanding. The Fiery Furnace is a maze of canyons that takes you deep into the heart of sandstone country. The Devils Garden Trail is the longest in the park at over seven miles, including its various spurs to Arches attractions. The trail takes in eight arches altogether as it clambers over slickrock and down narrow rocky ledges.
Our final stop today, at the Devil's Garden Trail, was to take the moderately easy 1.6 mile trail to Landscape Arch. It was late in the day, 87 degrees and difficult to maneuver through the loose sand in areas. But, it was well worth the effort! Even though we'd read about the many animals living in the park the only thing we encountered today was a leopard lizard. We first spotted the plainer colored male and later a brightly marked foot long, long-nosed female leopard lizard (try saying that five times fast), or Gambelia wislizenii. Apparently the red/orange markings along the sides mean that this is a gravid female. It's bite is lethal to smaller lizards as well as insects and small rodents. She tried to intimidate me by rapidly digging with her front feet, then rearing up & almost hissing. It worked, I backed off! I certainly didn't want her landing on top of my head!
We spent an enjoyable 30 minutes or so checking out the famous Landscape Arch before deciding to head back. By the time we returned to the truck we had spent 6 hours exploring the park. It was a terrific day! I have to say that this 48 mile round trip road travels through some very spectacular scenery!!
Tomorrow we are heading to Montrose, Colorado. Our time is running short, so unfortunately we have to move on. But, if you are ever in eastern Utah, we highly recommend a visit to Arches National Park. One last thing, this post has 47 photos.
Sorry about there being so many, I just had a hard time narrowing it down!
Anyway, hope you enjoy sharing in our day....