While browsing through the web, looking for further explanations on arches and hoodoos and red rock country in general, and to identify some of the views in my old pictures, I came across Bob’s Arches – a gorgeous website full of pictures and infos on arches.
It’s Bob Fagley who has created this page, and nearly every arch in and around Moab is shown here.
Bob has a huge knowledge about the location of the arches, in his website he mentions that he has visited the locations for almost since 40 years.
If you have any question about arches or need to specify which arch you took a picture of – send him an email, he will help you if he knows the arch.
I did it for some of my Moab Corona Arch hike, and he could help me a lot !
Thanks Bob from here !
Bob's Arches website
Once upon a long time ago – several hundred million years ago, the area which is now the park, has been part of the so-called Paradox Bassin, a huge depression.
Saltwater from a nearby sea flow in and filled this bassin. The water eventually evaporated and left behind a saltbed or concentrated brine (KCl, CaSO4 x 2 H2O :-) ).
Over the millions of time, additional debris was deposited, leaving thin layers of limestone and shale. More debris was left, when some of the bassin surrounding edges were uplifted, and their tops eroded.
Fondest memory: Saltbed layers are not stable, when under pressure, as now with this overweight rock debris. So this bed moved plastically to places with less overweight (this is similar as ice movement in glaciers).
During late Jurassic and Cretaceous, around less than 200 mio years ago, this movement caused further uplift at the places from where the salt bed had moved, and over the time, anticlines or upfolds with a core of salt have formed that way. Further uplift 10-60 million years ago widened up the already existing folds, joints were formed in the anticlines – parallel fractures which gave room for more erosion.
The result were valleys with steep fractured walls – optimum surfaces for water to enter, freeze and cracking up the fissures and erode the rocks.
Among the NP on Colorado Plateau, Arches NP is the youngest.
But haha, then again - what is age :-)
Arches - as they are displaying themselves today - are not made for (geologic) eternity. They have a life cycle, as all living things. They begin as small holes in a wall or cliff, and subsequent weathering opens this up.
Same is for the pinnacles in this area.
Balanced Rock, for example, once had a little brother, Chip-off-the-old-block. He looked quite similar to Balanced Rock, but toppled off in winter 75/76.
On the second pic - the remains are still there - in the middle between Balanced Rock and the big fin.
Fondest memory: However, just next to Balanced Rock there is this big thick fin, which in some hundreds of thousands of years might have eroded to the new generation Balanced Rock :-)
If you have a closer look and compare the strata - they are the same for both, Balanced Rock and the thick one.
As for all natural environment, please respect the rules for visiting – leave nothing but footprints, take nothing but pictures.
As for the footprints, please respect also the cryptobiological crust, and leave the footsteps only on the marked trails.
The main stratum or rock layer which was exposed to erosion in Arches NP is Entrada Sandstone, composed of quartz sand, glued together by calcium cement.
This stratum furtheron consists of 3 members or divisions, which all have different properties (and thus erode different) due to their composition:
Dewey bridge - a lighter colored muddy sandstone, quite soft,
Slickrock - fine grained and thus erodes to more round objects,
Moab - which is white sandstone and caps the slickrock
The stratum below Entrada sandstone is Navajo sandstone, coarse-gained and thus erodes more rough.
Fondest memory: The first 3 pics are formations of slickrock - as the round edges show.
Pic 4 is moab member, where erosion brings out nearly every single layers of the formation.
Apart from their formation, "arches" need to follow some rules before they can be considered as an arch :-)
They must "be" a hole in a rock, completely formed by natural forces, the rock removed by water, wind or gravity, leaving a frame.
Depending on where they form, or how "old" they are (in terms of erosion that took place), they are classified into:
Cliff-wall arch - which would be Wall Arch for example, or Landscape Arch in it's beginnings;
Free-standing arch such as Delicate Arch or Landscape Arch today, or
Jug-handle arch as the famous Double-O-Arch.
Fondest memory: Who likes to read more about arches from the taxonomy point of view - there is a good Website on arches, which explains a lot.
Arches NP stretches out more or less in a north-south direction. Consider this to plan your trip for the best shots.
Early morning = when the sun is rising from the (plain) east with nearly no barrier between it and the rocks, you will get the best views on
inside Park Avenue,
Landscape Arch and
the others within Devils Garden.
Late afternoon you should be at
Balanced Rock, and
in the Garden of Eden.
But…. my most favourite pic is the one of Delicate Arch with the sun just behind it’s top – so it all depends :-)
The vibrant resort town of MOAB is the Gateway to Arches National Park and also Canyonlands. The town is located 5 miles south of the Park on Highway #191
Hans and stopped in Moab at the Visitor Center and got lots of good information and brochures (all free) on what to do and see in the area, esp Arches.
You need to know that the Park does NOT have any places to have a bite to eat nor any places to sleep, except the Park's campground, so most visitors stay in Moab as it offers, shopping, restaurants and accommodations - Hotels - Motels - Lodges - B & B's - Cabins, etc. It advertises that it has 1800 rooms to offer. That is so ironic, because Hans and I tried to find a place to stay after our long day in Arches, only to be frustrated by "No Vacancy" signs everywhere we went. It was a Friday night after all and we did not make any reservations anywhere. In hindsight I would have booked a room ahead, but we were so used to finding places at the end of the day, that we didn't consider it, just assumed we would find a place as it was a quiet time of the year for tourists. We ended up continuing on our journey and headed for the I-70 and Grand Junction.
Arches National Park lies atop an underground salt bed that is basically responsible for the arches, spires, sandstone fins and eroded monoliths found in the Park. Thousands of feet thick in places, this salt bed was deposited across the Colorado Plateau 300 million years ago when a sea actually flowed into the region and eventually evaporated. Over millions of years, residue from floods, winds and the oceans that came and went, blanketed the salt bed. The debris was compressed as rock, at one time possibly a mile thick.
Salt under pressure is unstable and the salt bed lying below Arches was no match for the weight of this thick cover of rock. The salt layer shifted, buckled, liquefied and repositioned itself, thrusting the rock layers upward as domes and whole sections fell into the cavities.
Faults deep in the Earth made the surface even more unstable. You can see the result of one 2,500 foot displacement, THE MOAB FAULT, from the visitor center.
Fault-caused vertical cracks later contributed to the development of Arches. As the salt's subsurface shifting shaped the Earth, surface erosion stripped off younger rock layers. Except for isolated remnants, today's major formations are salmon-colored Entrada Sandstone and buff-colored Navajo Sandstone.
Over time, water seeped into cracks, joints and folds. Ice formed in the fissures, expanding and putting pressure on the rock, breaking off bits and pieces. Wind later cleaned out the loose particles, leaving a series of free-standing fins. Wind and water then attacked these fins until the cementing material in some gave way and chunks of rock tumbled out. Many of these damaged fins collapsed. Others survived despite missing sections. These became the famous Arches.
In 1929, Arches Nationalpark was established as National Monument, in 1971 as National Park. It is categorized as high plain destert, with it's highest elevation at 1723 m (Elephant Butte) and it's lowest at 1245 m (Visitor Center).
Annual rainfall is around 250 mm per year.
On the 310 km2 areal, more than 1500 arches have been carved out by erosion into mostly Navajo and Entrada sandstone.
Entrance fee is 10 USD per car (valid for 7 days), it might be easier to get the Golden Eagle pass, if you intend to visit more national parks.
Except christmas day, the park is open all year round, in summer from 7:30 am to 6:30 pm, in winter from 8:00 am to 4:30 pm.
The best time to visit would be off- season, if it's not too hot and not too crowded. I was there in october (1990), with an average amount of other visitors, and in late december (1993), where sis and I seem to have been the only visitors :-)
Fondest memory: Park Map
If you like beforehand reading about your destination, you should not miss “Desert Solitude” by Edward Abbey. Born in 1927, Abbey came to US Southwest as a youngster. He did various jobs, and also worked for the national parks for a long time. Among this, he spent 2 years in Arches NP in it’s early days of being a National Monument.
"Desert Solitude” reflects about his love for pristine wilderness in general and in specific for this wild and rough desert.
Fondest memory: Quote from the book cover:
"This book may well seem like a ride on a buckling bronco. It's rough, tough, combative. The author is a rebel and an eloquent loner. His is a passionately felt, deeply poetic book. It has philosophy. It has humor. It has its share of nerve-tingling adventures - set down in a lean, racing prose, in a close-knit style of power and beauty."
If you like to read more about Edward Abbey - please check the Website
The main question surrounding the collapse of an Arch is WHY?
Erosion and gravity reign supreme over sandstone. For countless eons, rain, ice and groundwater slowly but relentlessly eat away at the natural calcium "cement" holding the Arch's sand grains together. Eventually there isn't enough of the cement left to withstand the forces of gravity and so the entire structure finally comes crashing down, as in the case of Wall Arch, when the remains of the ancient arch were found on the Devil's Garden Hiking Trail on August 5, 2008. Perhaps nature wedged off one piece of rock too many. This was the first major span to fall in 17 years. Wall Arch was 71 feet tall and 33 1/3 feet wide and was ranked 12th largest in size.
The last section of Arches is DEVILS GARDEN. Here you will find a varied area of Arches (eight all together) , Fins, Canyons and Slickrock. The Park's Campground is also located here.
Devils Garden Trailhead starts off gravelled, flat and easy. Hans and I did a bit of this trail, until it started to descend into the canyon and besides it was getting near the end of the afternoon.
One of the first arches you come to are Pine Tree, Tunnel Arch and Landscape Arch, the destination for most walkers. The huge 89 meter span is a little more than one meter thick at its narrowest point and has numerous fractures, making it prone to collapse one day.
Beyond this, the trail is rougher though more interesting and have many more arches including Navajo Arch, Partition Arch, Double O Arch, Dark Angel and Private Arch along the Primitive Trail.
One of the many interesting Plaques in the Park, explained about the ANCIENT SAND DUNES. I found it fascinating and it read as follows:
"This vast area was once covered by extensive Sand Dunes. Some 200 million years ago, winds from the Northwest carried tons of fine-grained sand into the area, creating an immense desert.
Over time, the sand drifts were covered by other layers of sediment, compressed and cemented by quartz and calcite into Navajo sandstone. erosion has since washed away the overlying layers, exposing the "Petrified" dunes.
One of the more impressive Arches in the Park, DOUBLE ARCH is a closely set pair of natural arches that share the same stone foundation. The Arches, which is located in the Windows Section, are reached by a short walk from the parking lot. Its massive size does not become apparent until you walk right up to it. Visitors can explore directly beneath and through the Arches.
Double Arch was formed differently than most of the others. It is known as a POTHOLE Arch as it was formed by water erosion from above rather than more typical erosion from the side.
It was one of my favourite Arches and it was easy to get to, even for me.