Rainbow Arch, located just above the visitor center in Arches National Park, collapsed sometime this winter. A park ranger noticed it was no longer standing during a hike in February. The arch was cataloged by Stevens and McCarrick as SA-137 and had a reported span of 11.7 feet.
A research team from the University of Utah, including Jeff Moore and Paul Geimer, had actually been studying this arch not long before the collapse. The “before collapse” photos here were taken by Jeff Moore, and the “after collapse” photos were taken by Paul Geimer. The “before-after” comparison below was assembled by Holly Walker.
The team made vibration measurements four times at the site in 2017, focusing on a prominent crack working through the center of the span that appeared to be putting the structure in jeopardy. The crack is circled in the photo below.
Close-up photo of the crack before collapse:
However, the team observed no changes in the crack or vibration characteristics over 12 months, and backed off on their monitoring program, believing the arch to be more stable that it appeared.
The collapse is bittersweet for the team, as it highlights and validates the fragility of these features, but unfortunately they were unable to record its last few weeks and months and identify accumulating damage.
Below is a photo after collapse.
While they can’t say for certain what caused the collapse, they believe the most likely explanation is that fatigue caused by daily and annual heating cycles finally stressed the tip of the crack enough to cause a runaway failure sometime this past winter.
Rainbow Arch lives on in the virtual world as an interactive 3D model made by the research team that can be found at https://skfb.ly/VMvB.
Famous Azure Window in Malta collapsed during a storm on March 8, 2017. Not only did the lintel itself collapse, but the entire outer column fell into the sea.
The arch was considered at risk of collapse and walking across the arch was prohibited only last December. And in January, a slab of rock fell off a lateral face of the outer column during high seas.
The spectacular arch was featured in many movies, including Game of Thrones. Some history of partial collapse can be seen in these movies. In the scene below from the 1981 movie Clash of the Titans, the underside of the arch is flat.
In the scene below from the 2002 movie The Count of Monte Christo, it can be seen that the underside of the lintel has fallen to create a more arced shape.
The October 2016 NABS Valley of Fire Arch Rally in Nevada was, as usual, filled with fun and camaraderie. Presented here is a slide show of photos taken by NABS President Larry Beck. Click on any image to start the slide show. The title of each image in the slide show provides the UTM WGS84 coordinates (the NABSQNO number) in zone 11S, and where present the name and catalog number of the arch. Catalog numbers refer to the Arch Hunter Books Valley of Fire series (available to NABS members).
Maine is not known for natural arches but there were four small ones reported in the Journal of Natural Arch Discoveries.
This October, Pat and I drove up the Maine coast stopping at some nice lighthouses. At the Portland Head Lighthouse in South Portland, ME you can see Portland Head Lighthouse Arch (ME-4), which is just south of the lighthouse.
Directions: In Portland, drive State Street south across the bridge into South Portland and turn left onto Cottage Road. Turn left into Ft. Williams State park and head to the lighthouse parking lot. You can see the arch to the south. Walk the trail south along the fence then go uphill to the top of the cliffs. Go left on a faint trail which goes on a pebble beach, and go right around the rocks to see the arch (only if it is low tide). The arch has a span of three feet.
Unfortunately nearby Portland Head Arch (ME-2) has fallen. It had a span of four feet. A scan of my old Polaroid photo is below.
Long Island Arch, Five Islands, Nova Scotia, collapsed on October 19, 2015. The arch, composed of basalt, was located on the Parrsboro Shore of the Bay of Fundy. The before and after photos above are courtesy of Fundy Geological Museum. The short video below includes footage from the day before the collapse, where rubble has already accumulated in the opening before the final collapse.
NABS is pleased to announce that we have selected an arch to name in honor of the memory of long-time member and SPAN publisher, Norm Self, who passed away earlier this year. Norm and his wife, Linda, lived in El Centro, CA for many years and Norm delighted in taking numerous friends out to see the arches on “Three-Arch Hill” in Gavilan Wash west of Picacho State Recreation Area in eastern Imperial County, CA. This area had special meaning to Norm and Linda and that played a role in selecting one of these arches to honor Norm.
The three arches located there have been unofficially referred to as Hag’s Tooth (CA-146), Gavilan Wash Arch (CA-145), and Eye of the Hawk (CA-144). “Hag’s Tooth” was aptly used for obvious reasons, and Gavilan Wash Arch was too small (5-foot span), so we chose Eye of the Hawk to honor Norm. Therefore, California arch NABSQNO 11S-707583-3657511 will hereafter be referred to by NABS as Norm’s Stargazer Arch (“Stargazer” was Norm’s old CB handle). Eye of the Hawk (“Gavilan” is Spanish for “hawk”) will be retained as an alternate designation. Of the three arches, Norm’s Stargazer Arch is the largest, northernmost, and highest elevation. It has a span of 20 feet and a height of 7 feet. NABS is planning a visit to these arches at the end of our next Rally.
Here are photos of the three arches by Dave Kennedy: