Soil erosion is not only an environmental issue; it also causes huge losses to the economy. The U. This value includes lost productivity, along with sedimentation and water pollution. Terraced farming needs to be implemented to make hillside agriculture manageable. Terraces prevent erosion and allow more water to flow to crops. In addition, hillside farm fields need full crop cover to help keep the soil in place.
This can be accomplished by intercropping, which means growing two crops together in the same field, such as planting rows of maize or soybean between rows of oil palm trees. For smallholders, agroforestry systems where a diverse set of crops, including trees, are grown together can be effective. Access to manure improves the organic matter of the soil, which inhibits erosion. Finally, alternating deep-rooted and shallow-rooted crops improves soil structure and reduces erosion at the same time.
Although the science of sustainable land management has been gaining support, the socio-economic context often makes implementation difficult. Sustainable land practices need to be financially viable for farmers. Governments and banks must help farmers get access to credit and support in implementing erosion prevention.
This is not only a good deal for the farmer, but for the whole community. The key to managing and reducing soil erosion is to rehabilitate already-damaged land , stop further degradation and put erosion-preventative measures at the core of land management policy. In this way, we can help prevent hunger and mitigate the climate crisis. To learn more about WRI's work restoring eroded soils, click here.
WRI relies on the generosity of donors like you to turn research into action. You can support our work by making a gift today or exploring other ways to give. In the winter and spring of , winds eroded 45 million tons of dust from a spot called the Bodele Depression in the desert of northern Chad all the way across the Atlantic Ocean to Brazil.
Also called industrial agriculture. Hurricanes are the same thing as typhoons, but usually located in the Atlantic Ocean region. The last ice age peaked about 20, years ago. Also called glacial age.
Also called iron oxide or ferric oxide. The current sea level rise is 1. Also called a storm tide. Typhoons are the same thing as hurricanes, but usually located in the Pacific or Indian Ocean region.
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The rock cycle is a web of processes that outlines how each of the three major rock types—igneous, metamorphic, and sedimentary—form and break down based on the different applications of heat and pressure over time. For example, sedimentary rock shale becomes slate when heat and pressure are added. The more heat and pressure you add, the further the rock metamorphoses until it becomes gneiss. If it is heated further, the rock will melt completely and reform as an igneous rock.
Empower your students to learn about the rock cycle with this collection of resources. Erosion is the process where rocks are broken down by natural forces such as wind or water. There are two main types of erosion: chemical and physical. In physical erosion, the rock breaks down but its chemical composition remains the same, such as during a landslide or bioerosion, when plants take root and crack rocks.
Explore the process of erosion with this collection of resources. Weathering is the process of the weakening and breakdown of rocks, metals, and manmade objects. There are two main types of weathering: chemical and physical. An example of chemical weathering is acid rain. Caused mostly by the burning of fossil fuels, acid rain is a form of precipitation with high levels of sulfuric acid, which can cause erosion in the materials in which it comes in contact.
An example of physical weathering is wind blowing across the desert playas. This process causes rocks to form a specific pyramid-like shape and they are called ventifacts. Select from these resources to teach about the process of weathering in your classroom.
Meet Walter, a friendly animal who will guide you on your quest for knowledge about erosion and weathering. You will begin your journey by doing different activities to that will simulate weathering and erosion.
The game continues with a variety of activities and information. At the end, you will play a bonus arcade game to award you for your good work. Join our community of educators and receive the latest information on National Geographic's resources for you and your students. Skip to content. Twitter Facebook Pinterest Google Classroom. Encyclopedic Entry Vocabulary. Erosion is the geological process in which earthen materials are worn away and transported by natural forces such as wind or water.
A similar process, weathering , breaks down or dissolve s rock , but does not involve movement. Erosion is the opposite of deposition , the geological process in which earthen materials are deposited, or built up, on a landform. Most erosion is performed by liquid water, wind, or ice usually in the form of a glacier.
If the wind is dust y, or water or glacial ice is muddy, erosion is taking place. The brown color indicates that bits of rock and soil are suspended in the fluid air or water and being transported from one place to another.
This transported material is called sediment. Physical erosion describes the process of rocks changing their physical properties without changing their basic chemical composition. Physical erosion often causes rocks to get smaller or smoother. Rocks erode d through physical erosion often form clastic sediments. Clastic sediment s are composed of fragments of older rocks that have been transported from their place of origin. Landslide s and other forms of mass wasting are associated with physical weathering.
These processes cause rocks to dislodge from hillsides and crumble as they tumble down a slope. Plant growth can also contribute to physical erosion in a process called bioerosion. Plants break up earthen materials as they take root, and can create cracks and crevice s in rocks they encounter. Ice and liquid water can also contribute to physical erosion as their movement forces rocks to crash together or crack apart.
Some rocks shatter and crumble, while others are worn away. River rocks are often much smoother than rocks found elsewhere, for instance, because they have been eroded by constant contact with other river rocks. Weathering is the mechanical and chemical hammer that breaks down and sculpts the rocks. Erosion transports the fragments away. Working together they create and reveal marvels of nature from tumbling boulders high in the mountains to sandstone arches in the parched desert to polished cliffs braced against violent seas.
Water is nature's most versatile tool. For example, take rain on a frigid day. The water pools in cracks and crevices. Then, at night, the temperature drops and the water expands as it turns to ice, splitting the rock like a sledgehammer to a wedge.
The next day, under the beating sun, the ice melts and trickles the cracked fragments away. Repeated swings in temperature can also weaken and eventually fragment rock, which expands when hot and shrinks when cold. Such pulsing slowly turns stones in the arid desert to sand.
Likewise, constant cycles from wet to dry will crumble clay. Bits of sand are picked up and carried off by the wind, which can then blast the sides of nearby rocks, buffing and polishing them smooth. On the seashore, the action of waves chips away at cliffs and rakes the fragments back and forth into fine sand.
Plants and animals also take a heavy toll on Earth's hardened minerals. Lichens and mosses can squeeze into cracks and crevices, where they take root. As they grow, so do the cracks, eventually splitting into bits and pieces. Critters big and small trample, crush, and plow rocks as they scurry across the surface and burrow underground.
Plants and animals also produce acids that mix with rainwater, a combination that eats away at rocks. Rainwater also mixes with chemicals as it falls from the sky, forming an acidic concoction that dissolves rock. Back up on the mountains, snow and ice build up into glaciers that weigh on the rocks beneath and slowly push them downhill under the force of gravity. Together with advancing ice, the rocks carve out a path as the glacier slumps down the mountain.
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