Welcome to backyard geology.
I'm Arielle, an
educator at the Harvard
Museum of Natural History.
Today, we're going to
investigate mountains.
You might live near mountains,
or maybe you visited a mountain
or seen videos or pictures.
There are mountains
all over the world,
and not all mountains
look the same.
The Himalayas between
the Indian subcontinent
and the Tibetan plateau have
some of the highest mountains
on Earth.
And the Himalayas are
still getting bigger
as the Indian
subcontinent pushes up
into the Eurasian Plate.
I live near the
Appalachian Mountains.
They look really different
from the Himalayas,
much shorter and rounder.
But millions of years ago,
the Appalachian Mountains
were as tall as the
Himalayas are today.
So what happened to the
Appalachian Mountains?
How do mountains get shorter?
Let's do an investigation
to find out.
For this experiment, we'll
need some sand, a watering can
and water, and it's
helpful to have some place
to put your sand, like a
sheet pan or a sandbox.
First, put some
water on your sand--
not too much, or
it'll get drippy.
Then, build your sand into
a tall pointed mountain.
We'll make it look kind
of like the Himalayas.
Now, since this
is your mountain,
you get to be in
control of the weather.
The water in this
watering can is going
to be the rain and the snow.
Drip the water over the
top of your mountain.
Make sure you're getting
all over the mountain.
It doesn't just
rain in one place.
Let's take a look
at our mountain now.
How is it different?
I notice that my mountain isn't
as pointy as it used to be.
It's shorter and
rounder, and the sand
that used to be at the top
has fallen down to the bottom,
making the sides wider.
So what's going on here?
In real life, mountains
get a lot of weather--
wind, rain, ice, and snow.
Over many, many
years, that weather
can make a mountain
begin to break apart.
Scientists call this weathering.
Then, the small
bits of the mountain
might roll or slide
down the sides.
This is called erosion.
Over millions of years,
weathering and erosion
can change tall,
pointy mountains
into short, rounded mountains,
just like we saw here.
Now that you've tried
this experiment,
you might have more
questions about mountains.
Different mountain ranges have
different geologic stories.
You can find out more about
mountains on the internet
and from books.
What else can you discover?
Thanks for watching,
and keep exploring.
