An easy and fun science fair project that shows the effects of weathering can be performed and observed right in your backyard. Find an open area of your yard that receives lots of sunlight and will become wet during rainfall. Shovel dirt into a large pile, approximately 3 feet tall in this area. Create another dirt pile in your yard that is the same height as the first. Cover the second dirt pile with a tarp to prevent rain and sun from reaching the dirt. Observe both piles daily and record the weather conditions and the height of each pile. Over time, the exposed dirt pile will diminish in size due to wind, rain and other natural elements, whereas the covered pile will reduce in size much more slowly.
Purchase some pieces of shale, limestone and sandstone. Select one piece of shale, one of limestone and one of sandstone and place it inside a jar. Then select another piece of shale, limestone and sandstone and place them in a second jar. Fill the first jar with tap water and the second jar with vinegar, and place caps tightly on each jar. Over the next few days observe and record the appearance of the stones. Vinegar, which mimics acidic rain water, will break down the rocks much more quickly than tap water. Observe how the rocks react to the weathering in the vinegar jar compared with the way the rocks react in the tap water.
Lay out three flat, cooking sheet pans. In the first and second pans, pour a cup of sand into a small mountain in the middle of each pan. In the third pan, lay a cup of sand out flat along the bottom. Cover the second pan with tissue paper. Fill a measuring cup with half a cup of water, pour it into the first pan and then record how the exposed sand mountain changes. In the second pan, pour half a cup of water over the tissue paper, letting it filter onto the sand. This experiment explores weathering that occurs in sandy areas of the world such as deserts and beaches. The tissue paper simulates trees and brush, which protect the ground from weathering in areas where they grow. Observe and record how the sand changes. In the third pan, pour half a cup of water onto the flat sand, then observe and record the sand changes. Measure and record the difference in height of the sand piles in pans one and two. Take note of which sand piles were most affected by the water and why this occurred.
Place a cardboard box on the ground in your yard by your hose. At the bottom of the box, place four inches of mud and allow it to dry for an hour. Pour a four-inch layer of sand over the layer of mud. Over the sand, pour a layer of small gravel. Build a fourth layer, four inches thick, of regular, dry dirt. Place the hose inside the box and allow it to run over the layers. First, use low water pressure for five minutes in the box and observe and record the results; which layers are exposed and how many inches deep did the water go? Apply more water pressure to the box for 5 minutes and record the results; which layers are exposed after the water pressure increased? How many inches deep does the water run? The more water pressure you use, the more the layers of earth will erode; this demonstrates the different extremes of weathering that occur in nature.