Questions: Mountains, Valleys, and Plains

Question 1

What is the difference between a mountain and a plain?

• A. Mountains are made of rock and plains are made of soil
• B. Mountains are tall with steep sides and peaks, while plains are large, flat areas of land
• C. Plains are always near the ocean and mountains are always far from it
• D. There is no real difference -- they are the same thing

Answer: (B)

Mountains and plains are defined by their shape. Mountains rise high above the surrounding land with steep sides and pointed or rounded peaks. Plains are the opposite -- large areas of flat or gently rolling land that stretch over wide distances. Both are made of rock and soil, but their shapes are very different because they were formed by different forces.

Question 2

Mountains stay the same size and shape forever.

• T. True
• F. False

Answer: False

Mountains are constantly changing, but so slowly that you cannot see it in a human lifetime. Forces inside the Earth push mountains up, while rain, wind, ice, and rivers slowly wear them down. Over millions of years, mountains can grow taller, shrink, or be worn down to rolling hills. The Appalachian Mountains, for example, were once as tall as the Himalayas but have been worn down over hundreds of millions of years.

Question 3

You see a low area between two mountain ridges with a river flowing through the bottom. What is this landform called?

Model answer: This is a valley. Valleys are low areas between higher landforms like mountains or hills. Rivers often flow through the bottom of valleys because water flows to the lowest point. Valleys can be formed by rivers cutting into the land over time or by movements of Earth's crust.

Valleys are one of the most recognizable landforms. Connecting valleys to rivers reinforces the idea that water flows downhill and shapes the land as it goes.