Friday, December 17, 2010

Why I Love Geology 3: Dry Falls

Intriguing bit of history courtesy of the UK Daily Mail.Seems that in the late 1960's the U.S. Army Corps of Engineers was tasked with investigating cliff retreat along the smaller, American-side fall at Niagara. This is reported to have come about because of one journalist, a Mr. Cliff Spieler of the Niagara Falls Gazette.

Mister Spieler wrote about the large rock falls in 1931 and 1954 that had created a large talus pile at the bast of the American falls, and that a combination of continued rockfall and headward erosion could "kill" the falls. This caught on with the American public, and in late 1965, the U.S. and Canada set up an International Joint Commission. Two years later, the American Falls International Board recommended damming the Niagara River above the falls in order to conduct geotechnical analysis of the falls.The United States Army Corps of Engineers (USACE) – Buffalo District was assigned the project, and from June 9, to November 25, 1969 no water flowed over the American falls for the first time in nearly 12,000 years.

The USACE drill crews cored the sedimentary rock that formed the falls, scaled loose materials off the rock face, and installed several instruments, including extensometers, in suspected areas of weak rock. After a long period of preparation people were allowed into the dry riverbed, where they gathered coins tossed into the immense wishing well over the decades and just gawked at the scenery.Geologists scampered all over, measuring, sampling, performing dye tests and mapping joint and fracture patterns.Among the huge rock debris at the base of the falls were man-made debris and the bodies of a man, a deer, and
"the badly decomposed body of a woman jammed head first amongst the rocks about half way up talus bank. The woman was clad in a red and white horizontally striped jersey or dress and a narrow gold wedding band with the inscription “forget me not” on the inside."
No record of what the deer was wearing.

After Thanksgiving, 1969, the water was set free and has flowed over the falls ever since.

After five months of work including 46 core borings totaling 4,882 feet, mapping, probing, installing piezometers to measure water pressure on rock joints, extensometers to measure rock movements, and a further six years of study and opinion polling the IJC concluded that:

It was technically feasible to remove the talus but was not considered desirable.

The Falls could but should not be stabilized by artificial means

And that while the two flanks of the American Falls and the Goat Island flank of the Horseshoe Falls were sufficiently unstable to warrant remedial action a statistically minor element of risk from unpredictable rock movement would remain and must be accepted by the viewing public.So nothing more was ever done.

And the American falls still flow.


Lisa said...

As a friend who works for the USGS told me, most of his studies are just that -- expensive, exhaustive things that usually result in no action, as the damage is best left alone.

I do love (if one can say that) the wedged woman wearing the "narrow gold wedding band with the inscription 'forget me not' on the inside." The best laid plans ... but then again, she was not forgotten after all, in a sense.

FDChief said...

Wasn't that little bit about the woman fascinating? I kept trying to picture the whys and whens and whos, all the while transfixed by this image of her tipping headfirst over the falls, her cheerful candy-striped dress clinging to her like tears, plunging into the smoking mist like Lucifer never to rise again.

What sad little domestic tragedy lay behind that plunge? And, yes, she did attain a sort of immortality; here we are discussing her decades after her life ended at the base of the American Falls.