PDA

View Full Version : Spectacular collapse of famous arch caught on camera



kong
01-11-2013, 02:37 AM
Spectacular collapse of famous arch caught on camera
The arch at Tennessee Beach, just north of the Golden Gate Bridge in San Francisco, had been photographed hundreds of times over the years, but never like this. Robert Wills captured the total collapse of the famous arch in photos. Wills called it "a spectacular event," one that lasted less than 10 seconds.

A sequence of the slide can be found below, but here is what the arch looked like before the slide:
http://img59.imageshack.us/img59/1637/410877.jpg


Here is what the arch looked like after the slide:
http://img35.imageshack.us/img35/7123/410878.jpg

Over the holiday, Wills was on a short hike with his family to the beach in Marin County specifically to see the large waves that were forecasted with the passing storm.

"As we were admiring the waves, a crack and the ensuing sound of a waterfall of rocks caught our attention and everyone on the beach spun around to see a small stream of rock flowing down the cliff face below the arch," Wills wrote in a blog post last week. "This was exciting enough that we kept our cameras out and ready and our attention on the arch."

Two minutes later, a few chunks of rock fell from the underside of the arch before the arch started to buckle in on itself and squeeze out rock from beneath it, Wills related.

"The collapse of the arch followed and the entire surrounding hillside started to slip off into the ocean in a thundering roar as boulders the size of a piano crashed into the surf and the sand, sending up a large splash of debris that got me a little nervous despite my [more than 300-foot] distance," Wills wrote. "The small crowd of 15 or 20 people stood in awe, wondering if the show was over."

It was, except for one smaller rockfall and the discoloring of the water from the freshly fallen pile of rock and dirt in the waves.

Here's a look at the sequence of the slide:
http://img5.imageshack.us/img5/3139/410880.jpg
"It was pretty exciting," Wills told The Marin Independent Journal. "It was definitely a rush to see it."

Wills' father, Chris, is an engineering geologist with the California Geological Survey. He told the Journal that weaker rock likely had fallen away from the cliff over the years, creating the hole and the arch, and after several decades of pounding surf, water intrusion and gravity, the arch finally gave way.

"While rockfalls like this are not often seen, the presence of vertical cliffs near the ocean tell us that they are happening all the time," Wills wrote. "At most beaches you can even see sections of the cliff that look like fresh scars. So next time you are at the beach, look around and see how the cliffs have gradually fallen into the sea and don't always trust that cliff is going to stay there forever."

Photos courtesy of Robert Wills.