(upbeat music) - Niagara Falls, one of the most recognizable waterfalls in the entire world.

It's beautiful, majestic.

It's no wonder that thousands of people flock to see it every year.

Today, we're going to explore just what makes this geological wonder so amazing.

And zero in on the erosive power of water and ice.

(quirky music) Niagara Falls isn't famous for being the tallest waterfall in the world.

In fact, there are about 500 that are taller.

What makes Niagara Falls so impressive is the amount of water that's flowing over it every day.

Niagara has the highest flow rate of any existing waterfall in North America.

In the summer, more than 168,000 cubic meters of water go over the crest line of the falls every minute.

That's enough to fill 13,000 bathtubs every second.

It's a combination of height and volume that makes Niagara Falls so breathtaking and moving.

I mean, literally it's moving.

Niagara Falls hasn't always looked like it does today.

Over time, rocks and landscapes, well they change.

And why do they change?

It's 'cause of all this water.

Water, ice, and wind can weather and erode Earth's landforms.

Now I'm not talking about weather as in, oh, what's the temperature going to be?

Is it going to rain today?

But weathering.

The process that takes place where rocks are broken into smaller pieces.

So weathering is like a hammer that breaks down the rocks.

And erosion is the process that carries the fragments away.

Water is the main cause of erosion on Earth.

The greater the force of the water, the faster the rate of erosion.

The rapids above the falls reach a speed of about 25 miles per hour.

With the fastest speeds occurring at the falls themselves.

Niagara Falls is located in between two great lakes, Lake Erie and Lake Ontario.

These great lakes were formed 14,000 years ago when this area was covered in huge, massive glaciers.

As these glaciers melted, water flowed and carved out the rock below.

But not all rock breaks down the same way.

Let's look at Niagara Falls, for example.

The top of the falls is capped with a very strong rock called dolostone.

We call this the cap rock.

(gritty music) This Lockport dolostone is about 20 meters thick and protects the top of the falls where the water goes over it.

Underneath the cap rock is much softer rock.

(jazzy music) 25 meters of clays, and sandstones, and shales.

This rock gets weathered and eroded very easily by the water.

Eventually when enough of the soft rock gets broken down there's not enough rock to hold up the dolostone cap rock.

So it collapses into the Niagara River.

The green color of the water is a visible sign of the power of the mighty Niagara.

This color comes from dissolved rock that's being swept through the water and over the falls.

In fact, an estimated 60 tons of dissolved minerals go over the falls every minute.

It's this geologic nature of Niagara Falls that makes it so susceptible to erosion.

In the last 12,500 years, Niagara Falls has moved seven miles upstream from erosion.

That's almost 37,000 feet!

We could see the path of the erosion in the Niagara Gorge.

Every year, the falls erodes about one foot.

But without human intervention, Niagara Falls would erode up to three feet per year.

But why are the falls eroding less because of humans?

Some of the water is actually being diverted or redirected to a hydroelectric power plant.

The water is actually used to make electricity!

So with less water, there's less energy to break down and erode the rock.

Niagara Falls is a great place to explore weathering, erosion, and the power of water.

But I have another idea.

Let's do an experiment that will allow us to see the effects that energy has on rock and sediment.

Let's head to the backyard.

(mysterious music) We said that the greater the force of the water, the faster the rate of erosion.

So let's try it out.

So the sand I have here represents the geosphere, so all the rocks and landforms.

Let's see what happens when we add a bit of water.

With this dropper.

Hm, that's pretty good.

So there's a little displacement.

You can actually get a lot of erosion with just this amount of water.

But it takes a lot more time.

Let's speed things up and increase the energy with the water in this cup.

Oh no.

Oh, crashing down.

Oh boy.

Oh boy.

Man down.

Now we're beginning to see some erosion.

But let's increase it even more with the energy in this bucket.

Oh, oh boy.

(water splashing) Awesome.

To get closer to the force of the water we saw in action at Niagara Falls we're going to need something stronger.

(Sarajane laughs) (water whooshing) Whoa!

Oh no, my castle.

Now that's more like it!

I think we've successfully recreated the fury of the falls.

(jaunty music) We've been talking a lot about weathering and erosion in this video.

But if you're interested in learning more check out our Compact Science viewer challenge, where you can experiment with erosion at home.

All you need is some water and some candy.

Get all the instructions on our website.

And be sure to share your results in the comments below.

I'm Sarajane Gomlak-Green with Compact Science.

Until next time, stay curious.

(dynamic music) - [Announcer] Compact Science is funded by the Joy Family Foundation.

- We've been talking a lot about weathering and erosion.

Oh, sorry.

Mulligan, okay.

I'm jiggling it out.

Am I sufficiently under the burrito?

Niagara Falls, one of the most recognizable waterfalls in the whole world.

It's beautiful, it's majestic.

What, oh, wait.

Nevermind.