We were looking through some photography from Ansel Adams. In his work, some of the mountains and valleys look almost organic. My son asked how the rock got so smooth. And so a discussion on weathering and erosion began.
Mountains do not last forever. As they age, they are torn down by persistent and slow forces of weathering.
When the weather causes rocks to break down into progressively it is called weathering. These rocks simply break down, but do not shift. Water freezes and thaws on a surface cause a chemical reaction which loosens the bonds holding rocks together. Over time, a large bedrock can be broken down into smaller and smaller pieces, so much they can become dirt.
Weathering is common on a surface exposed to the atmosphere. However, it is important to note that weathering does not stop at the surface. Weathering can extend downward into the Earth’s crust, where cracks, fissures, and microscopic holes allow water to penetrate and cause change.
Though water is an important force that effects weathering, but other forces include the atmosphere, plant and animal life.
Atmospheric gases penetrate into rocks openings breaking them down. Other forces such as plant roots, microscopic animals, plants, and digging animals also break down rocks.
In order to see weathering in effect, we slowly poured trickling water on bouillon cubes in a bowl. We were able to see first hand how the cube (representing a rock formation) is slowly breaking it down.
For other weathering experiments, check out this site.
Homeschool Activities by SmartTutor.com
Article by Nuria Almeida
Photo By freefotouk