Earth's Surface & Water

Earth's surface is made of land and water, and water is found in many different places all around our planet.

Reading is good — doing is better. Practice Earth's surface & water as an interactive lesson.

Definition

Earth's surface is the outside layer of our planet that we can see and touch. It is covered by two main things: land (like mountains, hills, and flat plains) and water (like oceans, lakes, rivers, and streams). Most of Earth's surface is actually covered by water, not land.

Remember the rule

More water than land! About 3 out of every 4 parts of Earth's surface are covered by water.

Key words

Surface: The outside or top layer of something — like the skin of the Earth.
Ocean: A huge, deep body of salt water. Earth has five oceans, and they cover most of the planet.
Lake: A body of water with land all around it. Lakes can be big or small.
River: A long, moving stream of fresh water that flows downhill into a lake or ocean.
Mountain: A very tall, high area of land that rises up above the land around it.
Plain: A large, flat area of land with few or no hills or mountains.
Fresh water: Water that is not salty, like the water in rivers, lakes, and most drinking water.
Salt water: Water that has a lot of salt mixed in, like the water in oceans and seas.

Worked examples

You look at a globe. Which color covers more space — blue or green and brown?

→ Blue covers more space. Blue stands for water, and water covers more of Earth than land does. · This is why Earth is sometimes called the 'Blue Planet.'

Your friend says lakes and oceans both hold water, so they must be the same. Are they?

→ No, they are different. Oceans are much bigger and hold salt water. Lakes are smaller and almost always hold fresh water. · Salt water and fresh water are not the same — you cannot drink ocean water safely.

A river starts high up in the mountains. Which way does it flow — uphill or downhill?

→ A river always flows downhill because gravity pulls the water down toward lower land, and eventually into a lake or ocean.

Name two types of land and two types of water you might find on Earth's surface.

→ Land: mountains and plains. Water: oceans and rivers. There are many others too, like hills, valleys, lakes, and streams.

Is the water you drink from the tap more like ocean water or lake water?

→ It is more like lake water because it is fresh water with no salt. Drinking water often comes from rivers, lakes, or underground fresh water sources. · We cannot drink ocean water because the salt would make us sick.

Common mistakes

Thinking Earth is mostly land — it is actually mostly water (about 71% is covered by water).
Mixing up fresh water and salt water — oceans are salt water, but most rivers and lakes are fresh water.
Thinking rivers flow in any direction — rivers always flow downhill because of gravity.
Confusing a lake with an ocean — a lake has land all the way around it and is much smaller than an ocean.
Thinking all water on Earth looks the same — water can be liquid in oceans and rivers, frozen as ice in glaciers, or even water vapor in the air.

FAQs

Why is there so much water on Earth?

Scientists believe water came to Earth billions of years ago from volcanoes releasing steam and possibly from space rocks called comets. Over a very long time, all that water filled the oceans.

Can we drink water from the ocean?

No. Ocean water has too much salt in it. Drinking it would actually make your body lose more water and make you sicker. We need fresh water to drink.

What is the biggest ocean on Earth?

The Pacific Ocean is the biggest. It is so large that all of Earth's land could fit inside it!

Where does river water go?

Most rivers flow downhill until they empty into a larger body of water, like a lake or an ocean. The water then evaporates, forms clouds, and falls back as rain — starting the cycle again.

Are mountains and hills the same thing?

They are similar but not the same. Mountains are much taller and steeper than hills. Hills are lower and have gentler, more rounded tops.

What is a glacier and is it part of Earth's water?

Yes! A glacier is a huge, slow-moving mass of ice found in very cold places. Glaciers are frozen fresh water and are an important part of Earth's water supply.

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