22 September 2008
Don’t fall in! Field trip to Niagara Gorge
Posted by Jessica Ball
Thanks for all the comments on the last entry…I’m working out my problems, really! And you’ve all been very helpful. (And thanks to Silver Fox for the “Arte y Pico” award! I’ve always wanted a cool swoopy angel trophy. Now I’ll have to start thinking about who to pass it on to…) However, I feel I’ve slacked off long enough and it’s time to start writing about geology again. I went on a great field trip to Niagara Gorge on Thursday, and, naturally, I have lots of photos.
Niagara Gorge (the area above the Falls) is around 12,000 years old, cut into Ordovician and Silurian rocks (mainly dolomites, shales, sandstones, and limestones) as well as (in the Upper Gorge) Wisconsin glacial deposits. The Falls have eroded back 7 miles toward Lake Erie in the last 12,500 years, although because of decreased flow the erosion rate is now only about 1 ft/year. On a normal day, the power plants in the Gorge above the Falls restrict the flow of water through the Gorge to about 75% during the day in peak tourist season, and 25% at night and off-peak. (This actually reminded me of something that I commented on when I first visited Niagara Falls at about age 10 – I told my parents that it seemed strange that the Falls were “on all the time” and didn’t get turned off at night, like other tourist attractions I’d been to. Ironically enough, the Falls can be turned off at night – and almost are!)
Our field trip began at Whirlpool State Park on the American side, overlooking Niagara Glen (a great place for bouldering, if you’re into that and have a passport). We spent a little time discussing the history of the Falls (including how the bend in the river occurs because the river hit the buried gorge and started cutting into glacial deposits that had filled a paleo-Niagara River system, formed >45,000 years ago). Then we climbed down a lot of stairs and switchbacks to get to the trail, which runs along the river to the Whirlpool. Along the trail, you can see lots of talus from the cliffs, the jetboats on the river (which are the only boats allowed in that part of the Gorge), and a place where the water is flowing in two directions at once, thanks to the Whirlpool. (Here’s some more cool trivia: under natural conditions, the Whirlpool circulates counterclockwise, but when the power plants take the river down to 1/4 flow rate, the Whirlpool reverses and flows clockwise.) The river is about 160 feet deep in that part of the Gorge, possibly 200 feet deep in the Whirlpool (although this is unconfirmed as of yet).
Now for the photos! I was using my cheap, “I won’t be devastated if this accidentally gets dropped in the dangerous and unswimmable river” digital camera, so they’re not as good a quality as I’d like, but they shouldn’t be too bad.
Here’s the group at the first overlook, looking roughly to the north at the Niagara Glen and one of the two power plants.
Looking south along the river at the Whirlpool.
The spot on the river where the (surface, at least) water appears to be flowing in two directions at once. It’s hard to see in this photo, but I believe the water on the near side of the river is flowing to the left (downstream), and the water on the far side is flowing to the right (upstream).
Looking out over the Whirlpool, with the lines of the Canadian gondola service overhead.
Silurian shales and limestones in the cliffs above the bend in the river.
The rapids leading into the Whirlpool. These are Class VI – the most dangerous kind. More than 2800 cubic m of water/second go through these at peak flow, compared with 1700 cubic m/second on the Colorado River’s Lava Falls Rapids. You’d have to be pretty stupid to try and navigate these, because not only is it incredibly dangerous, it’s illegal for any boat to be on this part of the river. There was, at one time, a rafting company that planned on taking people down this stretch of the river; on their maiden voyage, their boats capsized and three people were killed. This is also the location of North America’s largest series of standing waves. This is an awesome place to be in, but also quite humbling – one misstep on a slippery rock, and you’re toast, because there are no rescue boats on this part of the Niagara River.
A close-up of the wave. (Standing waves are constantly in motion – in this case, always crashing in the same spot. )
Here’s a video of the waves crashing.
Looks like it was a great field trip, and thanks for sharing – despite having lived on the east coast for more years than I care to count, I’ve never seen Niagara Falls. Those diagrams are great, and the photos do show what you wanted just fine, I think.It looks like, possibly, that the color of the river below the falls might be reflecting the glacial silt the falls/river has eroded into? It looks faintly the color of glacial turquoise.Now, don’t go all soft-rock on us, though! Good luck on your TAing f.t.
In my geography lesson on Wednesday our professor mentioned the turquoise colour of the water flowing in karst topography and she said that the colour was from dissolved calcium carbonate in the water. Peyton Lake in the Rockies is colored most likely by the rock flour from the glaciers. I’m not certain that this is correct, someone more qualified than I can offer expert advice.
Thank you for the interesting fieldtrip notes and photographs, Donald
Hi Donald – I think the color of the water in the Niagara river just at the Falls is a combination of things. It does flow over dolostone, which is a magnesium calcium carbonate, and I can say from experience that tap water is very “hard”, so there’s probably a good concentration of carbonate ions in there. However, the Falls themselves churn up and aerate the water and there are a lot of rapids in the Niagara Gorge, so I suspect the milky color also comes from tiny bubbles refracting the light. The water itself is naturally blue-green, so adding the carbonate and bubbles would produce the same sort of milky color you see from rock flour in areas where there are glaciers. (The last glaciers in Western New York were gone by 12,000 years ago, so it’s not related to the same process as the color in alpine lakes like Peyto.)
It’s Peyto Lake, some great Photographs of the colourful lake, just Google.
The niagara gorge has been done a couple of times now. It’s not outside the grasp of the best paddlers. https://www.facebook.com/bennymarr/videos/417014088447778/