Then and Now

Balanced Rock

A massive rock perched on a smaller pedestal. A smaller pinnacle stands to the right. A massive rock perched on a smaller pedestal. A smaller pinnacle stands to the right.

Left image
Credit: NPS

Right image
Credit: NPS/Neal Herbert

Balanced Rock is made of two different rock formations. The rock itself is Entrada Sandstone, the primary arch-building formation in the park. The pedestal it sits on is part of the Carmel Formation, which erodes more easily.

Formations in the park are consantly changing. Note the small pillar to the right of Balanced Rock in the historic photo. That formation, dubbed "Chip Off The Old Block," fell in the winter of 1975-76.

Wall Arch Collapse

a broad, stone arch viewed from below a broad, stone arch viewed from below

Left image
Wall Arch prior to its collapse
Credit: NPS

Right image
After the collapse of Wall Arch
Credit: NPS

When Wall Arch fell in the nighttime hours of August 4, 2008, it was a big surprise. Wall Arch was one of the major arches in Devils Garden. Though there were no witnesses, campers in Devils Garden reported hearing a loud rumbling noise.

Skyline Arch Rockfall

an arch with a large boulder on one side an arch with a large boulder on one side

Left image
Skyline Arch before the 1940 rock fall
Credit: NPS Photo

Right image
Skyline Arch after the 1940 rock fall
Credit: NPS Photo

Arches usually form slowly, but quick and dramatic changes do occur. In 1940, a large boulder suddenly fell out of Skyline Arch, roughly doubling the size of the opening.

The arch now has a span of 71 feet (21.6 m) and a height of 33.5 feet (10.2 m).

Marching Men

a black and white photo of stone spires a dead juniper tree is in the foreground with two living junipers to the right. a black and white photo of stone spires a dead juniper tree is in the foreground with two living junipers to the right.

Left image
Credit: NPS

Right image
Credit: NPS

On the Colorado Plateau, sparse rainfall and nutrient-poor soils facilitate slow rates of native plant growth and decay. Captured inadvertently by a scenic photo in the early 1920s, a dead juniper tree remains virtually unchanged nearly 100 years later. Nearby, two living junipers appear to have grown little. How long might a dead tree like this last where you live?

North Window

a black and white photo of North Window. A man stands under the arch on the right side. There are plants and soil on the stone below the arch. a black and white photo of North Window. A man stands under the arch on the right side. There are plants and soil on the stone below the arch.

Left image
Credit: NPS

Right image
Credit: NPS

From 1944 to 2015, several million people from around the world have enjoyed North Window Arch. As we can see in this comparison, soil erosion is a serious concern as regional visitation increases. 

The desert may look rugged, but its ancient shrubs and biological soil crusts have few defenses against trampling from human feet or off-road vehicles. You can us protect the desert environment by staying on established roads and trails.

Arches Entrance

A black and white photo shows a sign reading "Arches National Monument" and a 1950s-era car sit in front of a tall rock wall in the background A black and white photo shows a sign reading "Arches National Monument" and a 1950s-era car sit in front of a tall rock wall in the background

Left image
A 1950s-era photo of the entrance to Arches National Monument
Credit: NPS

Right image
A 2010s-era photo of the entrance to Arches National Park
Credit: NPS/Neal Herbert

Last updated: April 9, 2020

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Moab , UT 84532

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435 719-2299

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