Weathering: Definition & Explanation

Instructor
Maria Howard

Maria is a teacher and a learning specialist and has master's degrees in literature and education.

Expert Contributor
Matthew Bergstresser

Matthew has a Master of Arts degree in Physics Education. He has taught high school chemistry and physics for 14 years.

Discover how rocks and minerals are broken down by chemical and mechanical forms of weathering. Learn about some of the many geological formations created by weathering, from large caves to beautiful arches made of rock. Updated: 05/29/2020

From Boulders to Arches

Arches National Park in the U.S. state of Utah is home to a set of geological marvels called arches. Arches are naturally-occurring rock formations, like the upside down letter U. The Landscape Arch, at 93 meters across (306 feet), is the largest in the world and, like other arches, seems to defy gravity.

The Landscape Arch is one of over 2,000 arches in Arches National Park in Utah.
Photo of the Landscape Arch

Obviously, large rocks don't just immediately spring up as arches, but, like sculptures, are chipped away and refined over a long period of time until something unique and beautiful is formed.

What Is Weathering?

Instead of using a chisel like a sculptor, rocks and minerals are broken down in many different ways through a process called weathering. From water and wind to plants and animals, the earth puts all types of rock through natural wear and tear. The pieces of broken rock are then carried away by erosion and are deposited in rivers, lakes, and oceans.

Weathering can be both mechanical and chemical, and they both often work together at the same time. Mechanical weathering causes physical changes (the beautiful arches of Arches National Park), while chemical weathering changes the chemical makeup of the material being weathered (the rusting of iron through oxidation).

Mechanical Weathering: Let's Get Physical

Water

Mechanical weathering wears away at rock through physical forces, causing it to crumble and break apart. The Grand Canyon was created by mechanical weathering (and its pal erosion), as water from the Colorado River pushed past the rocky surface of the canyon for millions of years, making a deeper and deeper V-shape. At its deepest, the canyon is 1.6 kilometers deep (1 mile), where you can stack three Empire State Buildings on top of each other and still have room left over.

Many forces created the Grand Canyon, but the Grand Canyon was primarily formed by the water of the Colorado River.
Photo of the Grand Canyon

Water is powerful stuff. It drips down between the small cracks in rocks, and freezing temperatures cause it to expand and deepen the cracks. Saltwater does double duty, with both the water and the salt crystals working to break up rocks. Some types of rock, like clay, absorb water, causing them to crumble from the moisture (think of the way coffee can soften even the hardest of cookies).

Temperature

Over time, changes in temperature cause rock to repeatedly expand (grow bigger) and contract (grow smaller), which weakens them and leads to breakage. Deserts, in particular, have very high temperatures during the day and very low temperatures at night. Sculpted by other elements like wind, deserts are the site of the world's most spectacular geological formations, like the Landscape Arch in Utah.

Salt

In addition to being in a desert, Arches National Park is also located on an underground bed of salt, left over from when the ocean reached the region 300 million years before. Salt is a less stable foundation than other rocks and is more easily weathered by wind, water, and changing temperatures. Besides its famous arches, the U.S. state of Utah is also known for spires of rock called hoodoos.

Hoodoos at Bryce National Park, also in Utah
Photo of hoodoos

Plants and Animals

As animals and plants are hard at work living and growing, they also break and weaken the rocks around them. Moles, rabbits, and other animals burrow holes and tread heavily over the ground, and if you've ever seen tree roots grow around large boulders, you know that plant roots are powerful enough to break through even very large rocks. So, too, can smaller plants like moss weather rock on a smaller scale.

To unlock this lesson you must be a Study.com Member.
Create your account

Practice:
Weathering: Definition & Explanation Quiz

Instructions: Choose an answer and click 'Next'. You will receive your score and answers at the end.

1/5 completed

Weathering is the process of ________.

Create Your Account To Take This Quiz

As a member, you'll also get unlimited access to over 84,000 lessons in math, English, science, history, and more. Plus, get practice tests, quizzes, and personalized coaching to help you succeed.

Try it now
It only takes a few minutes to setup and you can cancel any time.
Already registered? Log in here for access
Additional Activities

Weathering

Weathering is another term for erosion. There are several types of erosion, wind, flowing water and freezing/thawing water. Let's look at a few scenarios and determine what type of erosion it is.

Scenarios

1. You gather some stones on a beach that has large, powerful waves. The stones are very well rounded. How do you think the stones became so well rounded?

2. You gather some sand further up the beach away from the ocean. Under a microscope, the sand particles have sharp, jagged edges. There is no rounding visible in any of the grains. What type of weathering do you suspect occurred with the sand particles?

3. What type of weathering do you suspect occurs predominately in the location shown in Figure 1?


Figure 1


4. The Appalachian mountains in the Eastern United States are filled with foliage. What types of weathering would you suspect occurs there?

Solutions

1. Water erosion/wave action. The large, powerful waves act against the rocks, causing them to move over each other and rounding off their edges of long periods of time.

2. Jagged edges indicate wind erosion. The sand particles bounce around due to the wind causing the jagged edges.

3. Wind erosion predominately because of the dry desert where the Sphinx is located in Egypt.

4. Mountains usually have streams. Mountains with a lot of vegetation means constantly flowing streams due to plentiful rainfall. The Appalachian mountains are far enough from the equator and have high enough elevation to have water freezing in cracks of rocks; the water expands when it freezes, pushing the rocks apart.

Register to view this lesson

Are you a student or a teacher?

Unlock Your Education

See for yourself why 30 million people use Study.com

Become a Study.com member and start learning now.
Become a Member  Back
What teachers are saying about Study.com
Try it now
Create an account to start this course today
Used by over 30 million students worldwide
Create an account