Better late than never. Here we present a 12-minute video slide show of a NABS trip to Tassili National Park, Algeria, in 2006. Photos by Ray Millar, who had previously visited the area in 2003 so some photos from that trip are included as well. Music by Oliver Shanti.
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.
Natural Arch and Bridge Society member Ray Millar visited Libya in 2008 and offers this 9-minute video slide show of his trip, which includes a bunch of natural arches on the Akakus Plateau.
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.
Here is a 16-minute video slide show by Ray Millar:
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).
By Nick Terzakis
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.
The photo below shows two large natural arches at Legzira Beach, Morocco, in the Province D’Agadir about 10 kilometers north of Sidi Infi.
The arch in the foreground, NABSQNO 29R 391178 3257234 with an estimated span of 60 feet, collapsed on September 23, 2016. The remains are shown in the photo below.
The remaining arch, with an estimated span of 90 feet, still stands. Our own Guilain Debossens stands by the arch in the photo 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.