Arches National Park, Moab, Utah

(435) 719-2299
www.nps.gov/arch

Today, we ventured to the Arches National Park.  Below are excerpts I type from the "Visitor Guide" and the "Arches National Park" brochure.  I hope you enjoy them.

The park lies atop an underground salt bed that is responsible for the arches, spires, balanced rocks, sandstone fins, and eroded monoliths of this mecca for sightseers.

This is the parking lot at the Visitor's Ctr.  In the background you can see the road with the tiny car driving up.  We'll be going on there next.

Some sculptures outside the Visitors's Ctr.

Remember that wall behind the parking at the Visitor's Ctr?  And the little car on the road?  Well....I'm there now....

I am further up that wall you saw from the Visitor Ctr Parking Lot.  There is the entrance below.

Thousands of feet thick in places, this salt bed was deposited across the Colorado Plateau 300 million years ago when a sea 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 possible 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.

All the pictures below are affiliated with the Park Avenue 

Faults deep in the Earth made the surface even more unstable.  You 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, in which most arches form, and buff-colored Navajo Sandstone.

They stand like a layer cake over most of the park.  Over time water seeped into cracks, joints, and folds.  Ice formed in the fissures, expanding and pressuring the rock, breaking off bits and pieces. 
Wind later cleaned out the loose particles, leaving a series of freestanding 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, harder and better balanced, survived despite missing sections.  These became the famous arches.

Pothold arches are formed by chemical weathering as water collects in natural depressions and then eventually cuts through to the layer below.

Water.  The lack of it defines the desert, and yet, evidence of it's influence surrounds you.  Water's unequaled power to carve solid rock is responsible for the wondrous arches, towers, and other shapes that ignite your imagination.

Cracks filled with rainwater sustain diverse plant life, like the gnarled juniper tree and razor-sharp yucca.  Shallow pools called desert potholes teem with microscopic creatures and mean the difference between life and death for a thirsty bighorn ewe.

 Eight to ten inches a year is just enough rain for desert-adapted life, but what about park visitors?  Is there enough to share?

Yes.  Arches National Park provides water at the visitor center, campground, and Devil's Garden trailhead.

While mammals are active at night, but you might see mule deer, kit foxes, or more often jack-rabbits and cotton-tails kangaroo rats and other rodents and small reptiles.

Flocks of blue pinyon jays chatter in tree tops.  Migratory birds like mountain bluebirds and residents like golden eagles are seen by careful observers.

Desert soil may appear barren, but they teem with living organisms that bind loose, fragile soils together so they can support plant and animal life.  These organism-rich soils are a critical part of the ecosystem in canyon country.  Called "biological soils crusts," they prevent erosion, absorb water, and provide vital nutrients to plants.  This community of cyanobacteria, lichen, algae, and fungi grows extremely slowly.  A single foot-step can destroy hundreds of years of growth.