Mountains, canyons, deltas and straits: what shapes the land, and how the water moves across it.
The ground under your feet looks like it never changes. It does, just slowly. Plates push mountains up a couple of millimeters a year, and rivers carry away grains of sand one at a time. Give those small changes millions of years and you get the Himalaya and the Grand Canyon. On this page you'll learn the names geographers use for the shapes of land and water, how those shapes form, and how scientists read the clues.
What Is a Landform?
A landform is a natural feature of Earth's surface, a particular shape of the land. Geographers call the shape and height of the land in a place its terrain. Mountains, hills, plateaus and plains are the four major types of landforms. Valleys, canyons and basins are smaller landforms that you'll often find inside or between them.
Landforms aren't only on dry land. The ocean floor has mountains, plains and deep trenches too. And many landforms are named for the way land and water meet, like peninsulas and islands, which you'll see later on this page.
The Major Landforms
This drawing slices through an imaginary landscape so you can see each landform from the side, along with the rock underneath it.
A side view, or cross-section, of six landforms. From left to right: mountains, whose rock layers have been bent into folds; a V-shaped valley with a river at the bottom; a rounded hill; a flat plain sitting on flat layers of sediment; and a high, flat plateau with a canyon cut down through its rock layers. The heights are stretched so the shapes are easy to see. On a phone the drawing comes in two halves: left, then right.
Mountain
Land that rises steeply, high above the land around it, usually to a peak. Most mountains come in long chains called ranges, like the Himalaya in Asia or the Andes in South America.
Hill
Land that rises above its surroundings and has a rounded top. Hills are lower and gentler than mountains, usually less than 300 meters (1,000 feet) high.
Plateau
A large area of high, fairly flat land that rises sharply above the land around it on at least one side. The largest is the Tibetan Plateau in Asia, about 2.5 million square kilometers (1.5 million square miles), about four times the size of Texas.
Plain
A broad area of fairly flat, low land. Plains cover more than one-third of the world's land and are found on every continent. The Great Plains stretch across much of central North America.
Valley
Low land between hills or mountains, often with a river running through it. Valleys cut by rivers tend to be V-shaped. Valleys carved by glaciers, like the ones in Yosemite National Park in California, are U-shaped.
Canyon
A deep, narrow valley with very steep sides, usually cut by a river. The Grand Canyon in Arizona is the famous example.
What about deserts? A desert isn't a landform. It's a kind of place defined by how dry it is: most experts call land a desert if it gets no more than 25 centimeters (10 inches) of rain and snow a year. Deserts cover about one-fifth of Earth's land, and they can contain any landform. Sand dunes cover only about 10 percent of the world's deserts. Some deserts are rocky plateaus or mountains, and the largest desert in the world is ice-covered Antarctica.
Four Ways Land Gets Shaped
Some forces build land up. Others wear it down and move it somewhere else. Most landforms are the result of both, working at the same time.
1 Plates collide
Earth's outer shell is broken into huge tectonic plates that move a few centimeters a year. When two plates carrying continents push into each other, the crust crumples and folds upward. That's how the Himalaya formed: India ran into the rest of Asia starting 40 to 50 million years ago, and the two are still pushing together.
2 Volcanoes erupt
Melted rock called magma rises from deep underground. When it erupts as lava and ash and piles up, it can build mountains, islands and even whole plateaus. The Hawaiian Islands were built by volcanoes.
3 Erosion wears land down
Erosion is the wearing away of rock and soil by water, wind or ice. Rivers cut valleys and canyons. Glaciers scrape valleys into U shapes. Over time, erosion can turn sharp mountains into rounded hills.
4 Deposition builds land up
Everything erosion carries away has to land somewhere. Deposition is when water, wind or ice drops that material, called sediment. Layer after layer of sediment builds plains and deltas. The Huang He (Yellow River) in China has built a plain of about 409,500 square kilometers (158,000 square miles) this way.
How Do We Know? Two Stories Told by Instruments and Rock
Nobody has watched a mountain range rise or a canyon get cut. So how can scientists say what's happening, and when? Here are two examples.
1. GPS shows Mount Everest is still being pushed up
The same Global Positioning System that runs the map app on a phone can measure where a spot on the ground is to within millimeters, if a receiver is fixed to solid rock and left there for years. Scientists have set up GPS stations across the Himalaya. Their data show the rock near Mount Everest rising about 2 millimeters a year. That's tiny, but at that rate it would add up to 2 meters every thousand years. The cause is India, which is still pushing into the rest of Asia.
So does Everest get 2 millimeters taller every year? Not exactly. Wind, ice, rockfalls and rivers are wearing the mountains down at the same time, and the snow on the summit gets thicker or thinner. The height of the summit is measured separately. Survey teams from Nepal (in 2019) and China (in 2020) climbed to the top carrying satellite receivers. In December 2020 the two countries jointly announced a height of 8,848.86 meters, including the snow cap. That's usually rounded to 8,849 meters (29,032 feet).
2. The Grand Canyon's rock layers are a timeline
The walls of the Grand Canyon are striped with dozens of rock layers, most of them made from sediment that settled in seas, rivers or sand dunes long ago. Geologists read them using two simple rules:
Original horizontality: sediment settles in flat, level layers. If you find layers that are tilted or folded, something moved them later.
Superposition: in a stack of layers that hasn't been flipped, the layers at the bottom are the oldest and the ones on top are the youngest, just like a pile of laundry.
The rocks at the bottom of the inner canyon are about 1.8 billion years old. The Kaibab Limestone at the rim, about 270 million years old, formed on the floor of an ocean and now sits up to 9,000 feet (about 2,700 meters) above sea level. That means the land was lifted up a long way, and geologists date that uplift to about 70 to 30 million years ago.
The canyon itself is much younger than its rocks. Scientists dated the river with two clues. A layer of Hualapai Limestone, about 6 million years old, contains no river gravel, so the Colorado River wasn't flowing there yet. But river gravel lies right under a lava flow, the Sandy Point Basalt, that is 4.4 million years old, so by then the river was there. That puts the start of the river's carving at about 5 to 6 million years ago. Rock in the canyon walls is still falling, so today the Grand Canyon is getting wider faster than it's getting deeper.
Water on the Land
Water does a lot of the work of shaping land, and it gives us names for a whole second set of features.
River
Fresh water flowing downhill in a channel, toward a lake, the ocean or another river. A river and all the streams that feed it drain an area of land called its drainage basin.
Lake
A body of water surrounded by land. Most lakes are fresh water. A few, like the Caspian Sea and the Dead Sea, are salty because water leaves them only by evaporating, and the salt stays behind.
Delta
Land built from sediment where a river slows down as it enters a lake or the ocean. The river drops its load and splits into smaller channels called distributaries. The Nile delta in Egypt is one example. The Ganges-Brahmaputra delta, in India and Bangladesh, is huge. Not every river builds one: the Amazon has no delta, because strong Atlantic tides sweep its sediment away.
Waterfall
A place where a river drops over a steep edge, like a cliff. Angel Falls in Venezuela, the tallest, pours off the edge of a plateau.
The water cycle, briefly
Earth's water keeps moving in a loop called the water cycle. The sun warms the ocean, lakes and rivers, and some water evaporates, turning into an invisible gas called water vapor. The vapor rises and cools, then condenses into tiny droplets that make clouds. The droplets grow and fall as precipitation: rain, snow, sleet or hail. Most precipitation falls on the ocean. On land, some runs into rivers and lakes, and some soaks into the ground and becomes groundwater. Rivers and groundwater carry water back toward the sea, and the loop continues. Snow and ice can even turn straight into water vapor without melting first, a process called sublimation.
Where Land Meets Water
Coastlines have their own vocabulary. Here are the shapes geographers name most often, all on one made-up map.
An imaginary coastline seen from above. A river runs from the hills into a lake, then out to a delta at the head of a bay. A narrow strait separates an island from the mainland. An archipelago of small islands lies to the south. On the right, a peninsula sticks out into the sea, a gulf is almost closed in by land, and a thin isthmus connects the mainland to the land to the south-east. On a phone the map comes in two halves: west, then east.
Island
Land completely surrounded by water and smaller than a continent. Madagascar, off the south-east coast of Africa, is a large one.
Archipelago
A group of islands scattered close together. The Malay Archipelago in Southeast Asia has more than 25,000 islands. Japan is an archipelago too: a 2023 count by the Geospatial Information Authority of Japan found 14,125 islands.
Peninsula
Land almost entirely surrounded by water but joined to the mainland on one side. Spain and Portugal share the Iberian Peninsula, and most of Florida is a peninsula.
Isthmus
A narrow strip of land that connects two larger landmasses and separates two bodies of water. The Isthmus of Panama links North and South America and separates the Pacific from the Atlantic.
Strait
A narrow body of water that connects two larger bodies of water. The Strait of Gibraltar is the only natural link between the Mediterranean Sea and the Atlantic Ocean.
Bay
A body of water partly surrounded by land, with a wide opening to the sea. The Bay of Bengal, east of India, is the largest bay in the world.
Gulf
Like a bay, but usually larger and more closed in by land, with a narrower mouth. The Gulf of Guinea curves along the coast of West Africa.
Names don't always follow the rules. People named many bays and gulfs long before geographers agreed on definitions. Hudson Bay in Canada is much bigger than the Persian Gulf, for example. And notice the pattern: an isthmus is land connecting land, while a strait is water connecting water. If someone dug a canal across an isthmus, they'd turn it into a passage for ships, which is what the Panama Canal does.
How Much of Earth's Water Is Fresh?
Earth is a watery planet, but almost all of its water is salty. The U.S. Geological Survey (USGS) estimates Earth's total water supply at about 332.5 million cubic miles. Oceans, seas and bays alone hold about 96.5 percent of it. Here's how it splits up.
All of Earth's water (USGS estimate, rounded)
Kind of water
Share
Bar
Salt water: oceans, seas and bays, plus salty groundwater and lakes
about 97.5%
Fresh water
about 2.5%
Where the fresh water is (USGS estimate, rounded)
Where
Share of fresh water
Bar
Frozen in ice caps, glaciers and permanent snow
68.7%
Underground, as groundwater
30.1%
Lakes, rivers, swamps, soil, the air and living things
about 1.2%
Rivers and lakes supply most of the water people use every day, yet together they hold only about 1/150th of one percent of all the water on Earth. Rivers alone hold about 0.006 percent of the fresh water.
Record Holders
Here are some of the extreme places on Earth, plus one famous canyon. Measurements of the deepest and highest places vary a little between surveys, so these are the figures from the sources listed on each card.
Mount Everest
Record
Highest point on Earth above sea level
Height
8,849 m (29,032 ft); the 2020 survey gave 8,848.86 m, including the snow cap
Where
The Himalaya, on the border of Nepal and China (Tibet)
Other names
Chomolungma in Tibetan, Sagarmatha in Nepali
Did you know? Edmund Hillary of New Zealand and Tenzing Norgay, a Sherpa mountaineer, made the first recorded climb to the top together on May 29, 1953.
Sources: National Geographic Education; Britannica; Reuters
Challenger Deep
Record
Deepest known point in the ocean
Depth
About 10,935 m (35,876 ft) below the ocean surface
Where
The southern end of the Mariana Trench, in the western Pacific Ocean, southwest of Guam
Average ocean depth
About 3,682 m (12,080 ft), for comparison
Did you know? If Mount Everest sat at the bottom of the Challenger Deep, its peak would still be about 2.1 kilometers (1.3 miles) under water. The spot is named for HMS Challenger, a British ship whose crew first measured the trench's depth in 1875.
Sources: NOAA Ocean Service
Dead Sea shore
Record
Lowest land and lowest lake on Earth's surface
Elevation
About 430 m (1,410 ft) below sea level in the mid-2010s, and still dropping about 1 m (3 ft) a year
Where
Between Jordan to the east and Israel and the West Bank to the west
How it formed
It lies in a graben, a block of land that dropped down between faults in Earth's crust
Did you know? Nearly all of the Dead Sea's water comes from the Jordan River. Since the 1960s, Israel and Jordan have diverted much of the river's flow, so the lake keeps dropping, and sinkholes have opened up near parts of its shore.
Sources: Encyclopaedia Britannica
Lake Baikal
Records
Deepest lake and oldest freshwater lake in the world
Depth
1,620 m (5,315 ft) at its deepest
Age
About 20 to 25 million years
Where
Southern Siberia, Russia
Did you know? Baikal holds about one-fifth of all the fresh water on Earth's surface. More than 330 rivers flow into it, but only one, the Angara, flows out. Baikal seals live in its waters.
Sources: Encyclopaedia Britannica
Caspian Sea
Record
Largest lake in the world, and largest inland body of water
Area
About 386,400 km² (149,200 sq mi), larger than Japan
Surface
About 27 m (90 ft) below sea level
Shores
Five countries: Kazakhstan, Turkmenistan, Iran, Azerbaijan and Russia
Did you know? Despite its name, the Caspian counts as a lake because land surrounds it on every side. Its water is salty, though, and millions of years ago it was part of a much larger sea joined to the world ocean.
Sources: Encyclopaedia Britannica
Angel Falls
Record
Tallest waterfall in the world
Drop
979 m (3,212 ft)
Where
On the Churún River in Canaima National Park, Venezuela
Falls from
Auyán-Tepuí, a plateau with a flat top and steep cliff sides
Did you know? The falls are named for James Angel, an American adventurer who crash-landed his plane on a nearby flat-topped mountain in 1937.
Sources: Encyclopaedia Britannica
Grand Canyon
Famous for
Rock layers that record almost 2 billion years of Earth's history
Depth
About a vertical mile (5,000 ft, 1,524 m) at Grand Canyon Village; 6,000 ft (1,829 m) at its deepest
Size
The Colorado River runs 277 miles (446 km) through it; it is 10 miles (16 km) wide at Grand Canyon Village and up to 18 miles (29 km) in places
Where
Northern Arizona, U.S., in Grand Canyon National Park
Did you know? At Grand Canyon Village the canyon is 10 miles (16 km) from rim to rim, but the Colorado River at the bottom averages only about 300 feet (91 meters) across.
Sources: National Park Service
Game: Name That Feature
Each round, a yellow outline and a question mark point to one feature on the side view or the map. Pick its name. A right answer on your first try is worth 2 points, and on your second try, 1. There are 10 rounds, so a perfect game is 20.
Pick a name with the buttons below, or press the number keys 1 to 4. Use Tab to move between buttons and Enter to press one.
Get ready…
Round 1 of 10 · Score 0 · Best 0
How scoring works
Each round uses one of 16 features: six landforms on the side view and ten water and coast features on the map. You get four choices from the same drawing. A right answer earns 2 points on the first try and 1 point on the second. After two wrong tries the answer is shown and the round is worth 0. Your best score is saved only in this browser, as soon as a game ends.
Quiz: Landforms and Water
Ten questions. Choose one answer for each, then check your score. You can try as many times as you like.
Talk About It
What landforms and water features are near where you live? Which of the four forces (plates, volcanoes, erosion, deposition) do you think shaped them most?
Only about 2.5 percent of Earth's water is fresh, and most of that is frozen or underground. Should that change how people use water? Give one example.
Geologists dated the Grand Canyon's river from gravel under a lava flow. What's another place where the order of layers tells you what happened first, like a stack of papers on a desk or snow on a car?
Hudson Bay is bigger than the Persian Gulf, even though gulfs are "supposed" to be bigger. Should old place names be changed to match the definitions, or left alone?
Sources
National Geographic Education, Landform, Plain, Plateau and Desert (the four major landforms, hills under 300 meters, canyons, the share of land covered by plains, the Huang He plain, the Tibetan Plateau, what makes a desert).
National Geographic Education, Water Cycle and Delta (evaporation, condensation, precipitation, sublimation; distributaries, the Nile and Ganges-Brahmaputra deltas, why the Amazon has none).
National Geographic Education, Bay, Isthmus, Strait, Peninsula and Archipelago (definitions and examples, the Bay of Bengal, Hudson Bay and the Persian Gulf, the Malay Archipelago).
Geospatial Information Authority of Japan, 我が国の島を数えました (We counted Japan's islands), February 28, 2023 (14,125 islands, in Japanese).
National Geographic Education, Mount Everest (height, names, the 1953 climb).
Encyclopaedia Britannica (Britannica Kids), Tenzing Norgay (a Sherpa; reached the top with Hillary on May 29, 1953).
National Park Service, Grand Canyon National Park, Geology (superposition and original horizontality, rock ages, uplift, dating the river, glacial valleys, widening) and Basic Information (depth and width).
U.S. Geological Survey Water Science School, Where is Earth's water? (fresh and salt water shares, where fresh water is stored, total volume).
Written by Marco for Jugami's World Geography course. The side view, the coastline map and the game drawings are original SVG illustrations made for this page. They show imaginary places, simplified and not to scale, so that every feature fits in one picture.
