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Roger Weller, geology instructor                             

wellerr@cochise.edu
 

Niagara Falls
April Mangum
Physical Geology
Fall 2005
                                                              Niagara Falls

The Niagara Falls are categorized into three names

The American Falls

The Horseshoe Falls

The Bride Veil Falls

Ice Age history of the Niagara River and the Whirlpool Rapids

The Niagara Falls was once a sheet of ice approximately 18,000 years ago.  The southern region of Ontario was covered by 2-3 kilometers thick of ice as the sheet moved south the ice gouged out the basins of what is now known as the Great Lakes.  Then as the ice melted north for the last time, it released large amounts of the melt waters into those recently gouged out basins.  If you think about it the water in those lakes is fossil water or ancient water, and only less than 1% of that water is renewable on an annual basis.

Niagara Peninsula Becoming the Whirlpool

The Niagara Peninsula was free from the ice about or approximately 12,500 years ago.  As it retreated north, its melt waters began to flow through what are now Lake Erie, lake Ontario and Niagara River to the St. Lawrence River ending up at the Ocean. 

Then approximately 10,500 years ago, geological effects were taking place through an isostatic rebound.  Then it was interrupted.  The glacial melt waters go rerouted through northern Ontario, going around the southern route.  Lake Erie was only half its size it is now about 5,000 years ago because of it.  The Niagara River’s flow was reduced by about 10% and it halted in the Niagara Glen area.  The melt waters were then rerouted once again through southern Ontario restoring the fall to their original strength.  That is when it reached the Whirlpool.

The entanglement that went on there was a strong and short encounter, lasting only weeks, could have been only days according to geologists.  In those days or weeks, the Niagara River intertwined with an old riverbed, one that was buried and sealed during the previous ice age.  The then became a buried gorge; it tore out the glacial debris and scoured the old riverbed clean.  More than likely it was not a falls but a churning rapid then.  When everything was done, it left a 90-degree turn in the river and that is what we now call the Whirlpool Rapids.  http://www.niagarafrontier.com/whirlpoolrapids.html The falls were then re-established around the Whirlpool Rapids Bridge up the river to the right, and carved its way through the rock to where it is today.  http://www.whirlpooljet.com/07_video/whirlpool_high.wmv








 

Niagara Falls

Niagara Falls has eroded 11.4 kilometers (7.1 miles) during the last 12,300 years.

The slowing of the erosion rate is caused by two major factors:

1) The erosion resistant limestone cap the rock of the falls of Niagara they have been flowing over.  This limestone layer began approximately ½ kilometer north of the Rainbow Bridge.  As the Falls erode southward, the erosion rate will increase when it reaches Navy Island where the Falls reach a softer layer of rock.

2) The development of hydroelectric generating plants along the shoreline of the Niagara River has vastly reduced the rate of water flow through water diversion.

Just Credit Info and Photo to http://www.niagarafrontier.com/whirlpoolrapids.html







 

·          The Niagara Falls attracts more than 12 Million people a year.  The river falls over a cliff of dolostone and shale.  The Niagara Falls is the second largest falls on earth next to the Victoria Falls in Africa.  Being as it is one of the largest falls in the world.  The Great Lakes along with the fall helps supply 1/5 of the world’s fresh water.  The Niagara District sedimentary deposits include sandstone, shale, and marine limestone Just credit photo to Niagara Falls Thunder Alley

• The amount of water that flows over the three falls is different.  The American Falls water flow is much less than the Horseshoe Falls due to Goat Island.  The water's vertical descent ranges from 21 to 34 meters (70 to 110 feet) to the rock at the base of the falls.  Therefore, the Horseshoe Falls flows a lot faster because it does not have anything to slow it down.  Horseshoe Falls plunges 52 meters (170 feet) into the Maid of the Mist Pool.  The other fall has had many name changes in the past from the Luna Falls to Iris Falls and now to the Bridal Veil Falls.  Below is a table to show you just how much of the falls have been eroded in the last 163 years.  More than 168,000 cubic meters (6 million cubic feet) of water go over the Crestline every minute during peak daytime tourist hours.

Pictures of Historic Niagara Falls

http://www.niagarafrontier.com/tashapageone.html

http://www.niagarafrontier.com/tashapagetwo.html

Here are some photos I took April 2005

.

Works Cited

The best Web site I found for pictures and Video

http://www.infoniagara.com/attractions/falls/flash/american.html

Other sites

http://school.discovery.com/lessonplans/programs/niagarafalls/q.html

http://www.abacast.com/download/webinstall/index/.php?

http://niagarafallslive.com

http://iaw.com/~falls/origins.html#a

http://www.infoniagara.com/other/fast_facts/index.html

http://www.infoniagara.com/other/history/geo.html