“Climb the mountains and get their good tidings.”

John Muir

It’s an elk!” says 4-year-old Josh, pointing to the animal in the photograph. “It’s like a deer, but bigger. And it has big horns—out to here!”

“A reindeer?” Marcie asks.

“No,” says Josh. “Elks are bigger, and they live in the mountains.” He points to mountains in the photograph.

The children peer at the shapes in the background.

“See the white on top?” Josh says. “That’s snow. It’s cold at the top of mountains.”

A photo from Josh’s family vacation to Grand Teton and Yellowstone national parks has stimulated curiosity and discussion about mountains and the animals that live there. If you’re like their teacher, you will pay attention to the children’s interest and offer follow-up learning activities.

But first, make sure you understand some basics about the Earth and its geology so that you can accurately answer children’s questions.

The moving Earth
Imagine the Earth as a baseball. If you cut open a baseball, you would find a core of cork surrounded by layers of rubber, layers of string or wool yarn, and finally a cowhide skin on the outside. Similarly, if you could cut open the Earth, you would find a core of metallic rock surrounded by a layer of hot liquid rock, or magma. The next layer, the mantle, is made up of hard rock and magma. The outside is the Earth’s crust.

The Earth’s crust is relatively thin compared to its inner layers. The crust’s thickness depends upon location. Under the ocean floor, it is around 3 miles thick. Under flat land, it can be 22 miles thick, and under mountains, up to 27 miles thick.

The crust is not one solid piece but rather several pieces, called tectonic plates, that move around on top of the mantle. Two plates whose edges press against each other form a crack, or fault. The Balcones Fault in Texas and the San Andreas Fault in California are examples. The movement of the plates along a fault is usually too slight to feel. But when plates move suddenly against each other and the plates re-settle, the ground shakes and there is an earthquake.

At the edges of some plates are vents that allow magma from the mantle to flow upward. When the magma erupts at the surface, the magma is called lava, and the event is a volcano. A famous U.S. volcano was the 1980 eruption of Mount St. Helens in Washington state. Besides lava, the volcano may throw out hot ash, gas, and steam. As the lava cools, it hardens into rock. Over thousands of years, the cooled lava builds up into a cone-shaped mountain. Volcanoes also erupt deep under the sea, forming underwater mountains. If the process continues, the undersea mountains gradually rise up to the water surface, making islands. This is how the Hawaiian Islands were formed.

Tectonic plates are continuously pressing against each other. Over thousands of years, this movement changes the landscape. If a section of plate between two faults gets squeezed upward, it can form a mountain. If a section slips down, it can form a valley. In some cases, the plate’s rock layers, or strata, don’t crack but rather buckle and bend upward, forming a fold mountain. In other cases, the magma in the mantle pushes the rock layers upward like a cone or funnel. If the magna hardens into rock before reaching the surface, the result is a dome mountain.

As soon as mountains rise up, they begin to be worn down by natural forces such as water, wind, sun, ice, and gravity. The constant expansion and contraction resulting from temperature changes (warm days and cold nights) cracks the rock. Wind blows sand, blasting particles of rock loose. Moving water, both babbling streams and raging floods, wears down the mountain surface, dislodging rocks. Rivers that flow between mountains erode the surface, forming V-shaped canyons or gorges.

When heavy snow on a mountain is shaken loose by a loud noise or sudden movement and slides down a mountainside, the event is an avalanche. When more snow falls on a mountain peak in winter than evaporates in summer, the snow turns to ice. The ice may build up and begin to move downhill under the pressure of its own weight, creating a glacier, or river of ice. The glacier picks up rocks and boulders in its path and drags them along, carving out a U-shaped valley after the ice melts.

Mountains are home to different plants and animals, depending on the mountain’s location, height, and rainfall. Mountains with sparse rainfall will have fewer plants and animals than mountains with heavy rainfall. Although mountains vary widely, the life zones, or ecosystems, often follow a pattern, each with different plants and animals, as you move up the mountain. The foothills may contain sage, yucca, or juniper. Just above the foothills are hardwood forests of oak, poplar, and maple. A bit higher, the forests change to conifers such as pine, fir, and spruce. These trees thin out at a timberline, giving way to low-growing alpine plants that can survive the harsh climate. Nothing grows on the tallest peaks that are covered with snow and ice all year.

The temperate zones may contain meadows of grass and wildflowers in summer as well as lakes formed when melting snow and rain drain into low-lying areas. In North America, coyote, deer, and wild turkey live in the lower zones. Beaver, bear, and moose live among the lakes and streams. Elk, bison, eagles, wolves, and mountain lions live in higher regions, and bighorn sheep and mountain goats live just below the peaks.

The higher up a mountain you go, the thinner the air. In less dense air, the air molecules are farther apart, making it harder for oxygen to enter the bloodstream. Many visitors to Yellowstone National Park, most of which is at 7,500 feet above sea level, notice an increase in breathing and heart rates, as the heart pumps harder to get oxygen to the cells. Skiers and snowboarders are cautioned to let their bodies adjust for a day or two before hitting the slopes. Mountain climbers who have reached peaks 26,000 feet high (5 miles) usually have used bottled oxygen to assist their breathing.

Even so, some environments of 12,000 feet are inhabited, but only by indigenous people whose ancestors have lived at such heights for thousands of years. These include the Tibetans and Nepalese in the Himalayas and the Andean people in Peru and Bolivia. Over time, their bodies have developed more red blood cells, which allow more oxygen to be carried to their tissues.

Introduce children to mountains
Find out what children already know about mountains. Have they lived near mountains or traveled to them? Invite parents to bring photographs from vacations and build a library of resource books and colorful tourist brochures.

For children less familiar with mountains, you might set up a laptop and show the three-minute video, “Grinell and Glacier National Park,” from the Ken Burns film, “The National Parks: America’s Best Idea,” www.pbs.org/nationalparks/. Discuss the size of mountains relative to people. Talk about the weather on mountains and the plants and animals that live there.

Provide activities in learning centers, using the ones suggested below as ideas.

Language
Display photos provided by parents, clipped from magazines, or downloaded from the Internet. (Make sure photos are not copyrighted.) Stock your reading center with books from your local public library. Set up a laptop and bookmark websites with mountain photos. See the list at the end of this article.

At story time, read a book appropriate for the children in your classroom. With 3-year-olds, you might read the picture book My Home Is the Mountains: Who Am I? which contains 10 photographs of mountain animals such as a white hare, marmot (big squirrel), and a brown bear. Or you might choose I Live in the Mountains/Vivo en las montañas, a 20-page picture book with simple text in English and Spanish.

Four- and 5-year-olds would enjoy books like Mountain Town, which uses illustrations to describe life in a mining town, and Trouble with Trolls, a charming fictional tale about a girl who outwits mountain trolls to prevent them from taking her beloved pet dog.

Outdoor play
Invite children to build a mountain in sand or dirt. Provide small rocks to use as boulders, juniper twigs for trees, and ice chips for glaciers. Children may want to scoop out a small hole for a cave in the mountainside or carve out a canyon between mountain peaks. Provide animal and people figures for free play.

Snowball over the mountain
This simple game can provide vigorous exercise and be lots of fun.
1. Divide children into two teams.
2. Place a mountain (sheet) between them. The sheet can be tied to two chairs or held by two adults.
3. Invite children in one team to toss a snowball (white balloon, polystyrene ball, or wadded-up wrapping tissue) over the mountain to the other team. The other team catches it and tosses or bats it back.

Science
Invite children to gather rocks from the play yard or bring some from home. Place the rocks on the science table and encourage children to explore them. Provide a magnifying glass for close examination, and a balance scale for weighing. Invite children to sort them by color, shape, weight, or size.

Cracks in the Earth
Discuss how rocks are everywhere, on land and under the ocean. Rocks also make up mountains but are pressed together like one giant rock. But a mountain can develop cracks, big and small, which cause rocks to break off and fall down the side. Demonstrate one way mountains develop cracks using the activity below.

Here’s what you need:
modeling clay
spray bottle
plastic wrap
freezer

1. Invite children to roll damp modeling clay into two balls, about softball size.
2. Spray the outside of each ball with water, and wrap each ball separately in plastic wrap.
3. Place one ball in the freezer, and leave the other out.
4. After 24 hours, take the frozen ball out of the freezer, let it thaw to room temperature, and remove the plastic wrap. Ask children to compare the two balls of clay. The thawed one should have developed cracks.
5. Spray the thawed clay again, recover it with plastic wrap, refreeze, and take it out the next day. Repeat two or three more times and notice changes. Eventually the thawed clay ball will shatter. Discuss how the freezing and thawing is what happens to mountain slopes.

Settling sediment
Landforms are constantly changing. Sometimes the change is rapid, such as when a river overflows its banks, leaving silt and rocks. But typically the change is slow, taking many lifetimes. Pieces of rock are loosened by water, wind, and temperature changes and get deposited in a low area. Rock particles get buried on top of each other, sometimes trapping leaves and insects. The particles get compacted, and moisture combines with minerals to cement the material into sedimentary rock. Trapped plants and animals form fossils.

If possible, show examples of sedimentary rock, such as limestone, sandstone, and coal. Compare sedimentary with igneous rock, such as granite, which is formed from the cooling and hardening of magma.

Here’s what you need:
gravel
sand
dirt
jar with lid
water
plastic scoop

1. Invite children to scoop equal amounts of gravel, sand, and dirt in layers in the jar. Pour in water to cover.
2. Screw the lid tightly, and then shake the jar. Leave it in a place where it won’t be disturbed.
3. After a few days, look at the contents of the jar. The largest particles (gravel) will have settled at the bottom and smaller particles, or silt, at the top. Talk about how gravel settles because it’s heavier.

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