Weathering and Erosion

Have you ever wondered why rocks are so many different shapes, sizes and textures; or where sand, silt, soil, and clay come from? What about how the Grand Canyon was formed? Do you know why sidewalks are constructed with cracks in between each concrete section? Well, this week in Science we have been answering all of these questions while exploring agents of weathering (the breaking down or wearing away of rocks). We have investigated five agents of physical weathering: water, wind, temperature changes, ice, and roots of trees/plants. We also participated in two labs. Our Chalk Weathering Lab helped us better understand wind and water as agents of weathering, and our Chocolate Chip Cookie Lab led us into additional conversations about water as weathering. We have learned that rocks expand when they reach certain heated temperatures by the sun's thermal energy, and that they contract when they cool back down. This process of heating and cooling of rock causes them to weaken over time and weather (break down). In the textbook we also read about chemical weathering, which is caused by carbon dioxide forming a weak acid when it mixes with rainwater which changes the composition of rocks. There is just no way rocks in nature can escape the many agents that are constantly causing them to weather, even though most of these "changes" happen very slowly over time.

We have also explored erosion and recognize that there are four agents of erosion: wind, water, ice, and gravity. Next week we will participate in an outdoor water erosion and deposition lab, which should be a lot of fun.

To review information about weathering and erosion, watch this fun Study Jams video: http://studyjams.scholastic.com/studyjams/jams/science/rocks-minerals-landforms/weathering-and-erosion.htm 

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