C29 Weather/Erosion/Deposition

C29 Weathering Background 1 Earth processes are dynamic actions that occur both inside Earth and on its surface. Processes that break down Earth material, like water eroding a hill, is destructive. Processes that build up Earth material like deposition of sediments to create landforms like deltas are called constructive processes

C29 Weathering Background 2 Destructive forces are not always harmful and constructive forces are not always helpful. The effect of natural Earth processes depends on the situation. Before building anything, it helps to understand how certain Earth processes affect the land you plan to build on. Challenge Question: What happens when soil and rocks are moved from one place to another?

C29 Weathering (read p C24-28) Weathering: Earth process that breaks down rocks into smaller pieces like: Water freezing and melting in the rocks Water dissolving chemicals in the rocks Gravity making rocks fall and break Animals and plant roots cracking rocks

C29 Erosion 1 Erosion: movement of sediments from one place to another by wind, water, or ice. Water eroding Earth’s surface cuts into the ground, forming surface channels. These channels can be small or huge. Slow and steady water erosion over a long time can create valuable landscapes such as lakes, rivers, hills, canyons, & fertile plains.

C29 Erosion 2 Erosion can also be damaging. Problems can occur when land collapses or slides near buildings or roads, either quickly or slowly. Buildings and roads can move or fall, or can be damaged by falling rocks and sediments.

C29 Deposition 1 Deposition: When sediments are moved and left, or deposited, somewhere else. It occurs when sediments settle out of flowing water or wind as they slow down. So erosion and deposition are related. Deltas at the mouth of a river are examples of landforms formed by deposition.

C29 Deposition 2 Sometimes deposition can be helpful. Some sediments add important nutrients to the soil like in Mississippi and Nile River valleys. These floodplains form when rivers flood. After long periods of time, deposited sedi-ments can even form rocks like sandstone.

C29 Deposition 3 Sometimes deposition can be harmful. Sediments can build up and fill in wetlands, rivers, lakes, bays, and parts of the ocean. Sediments can cover the habitat areas needed by fish and other animals. For people, deposition in the wrong place can make the water too shallow for boats and clog pipes that provide water to cities.

C29 Earth Processes Weathering, erosion and deposition have occurred for billions of years. Many natural factors affect the rate of these processes. Human activities can accelerate them, too. Construction and farming are two human activities that cause the most erosion. By breaking up rocks, soil, and plant roots that hold land in place, it is easier to erode land.

C29 Pollution Sediments can carry pollution from one place to another. Sediments may contain toxic materials such as pesticides or chemicals from businesses. These become problems in the new area that they are deposited and must be cleaned up.

C29 Venn Diagram Make a Venn Diagram with 3 circles: Left circle is Weathering, Right circle is Erosion and Bottom circle is Deposition. Compare them by writing what is similar and different in the circles using terms from this activity: hills, rivers, cliffs, destruction, canyons, moves, deltas, breaks, sandstorm, sedimentary rocks, wind, lakes, landslide, water, sediment, builds, ice, construction

C29 Earth Process Concept Map Make an Earth Process concept map using: Deposition Water Environment Weathering Sediment Toxic-materials Erosion Farming Floodplains Lakes Deltas Construction Wind Ice Negative-effects Canyon Nutrients Positive-effects

C29 Weathering Analysis: Hour_ Name________________Date__ Copy and Explain in 1 paragraph each. Why is weathering important to erosion? Why does erosion always lead to deposition? Explain and give an example. Which do you think causes more erosion, a hurricane or a long period without rain? Explain and give details.