RAJESH NAYAK IMPORTANT CHAPTERS FROM SOCIAL SCIENCE AND SCIENCE (FROM NCERT CLASS 8 TH ) CONTENTS NCERT CLASS-VIII-SOCIAL SCIENCE, RESOURCES AND DEVELOPMENT-CHAPTER-2 & 4 NCERT CLASS-VIII-SCIENCE-CHAPTERS-1, 2, 7 & 18 TH
RAJESH NAYAK CLASS-VIII-SOCIAL SCIENCE-RESOURCES AND DEVELOPMENT CHAPTER-2- Land, Soil, Water, Natural Vegetation and Wildlife Resources Landslides the mass movement of rock, debris or earth down a slope. take place in conjunction with earthquakes, floods and volcanoes. A prolonged spell of rainfall can cause heavy landslide that can block the flow of river for quite some time. The formation of river blocks can cause havoc to the settlements downstream on its bursting. In the hilly terrain landslides have been a major and widely spread natural disaster that often strike life and property and occupy a position of major concern. Hazard mapping locate areas prone to landslides. SOIL The thin layer of grainy substance covering the surface of the earth is called soil. made up of organic matter, minerals and weathered rocks found on the earth. happens through the process of weathering. The right mix of minerals and organic matter make the soil fertile. Top soil with humus and vegetation Sub soil with sand, silt and clay Weathered rock material Parent rock -Determines colour, texture, chemical properties mineral, content, permeability Some methods of soil conservation are Mulching : The bare ground between plants is covered with a layer of organic matter like straw. It helps to retain soil moisture. Contour barriers : Stones, grass, soil are used to build barriers along contours. Trenches are made in front of the barriers to collect water. Rock dam : Rocks are piled up to slow down the flow of water. This prevents gullies and further soil loss. Terrace farming : These are made on the steep slopes so that flat surfaces are available to grow crops. They can reduce surface run-off and soil erosion. Intercropping : Different crops are grown in alternate rows and are sown at different times to protect the soil from rain wash. Contour ploughing : Ploughing parallel to the contours of a hill slope to form a natural barrier for water to flow down the slope. Shelter belts : In the coastal and dry regions, rows of trees are planted to check the wind movement to protect soil cover. Discharge of untreated or partially treated sewage, agricultural chemicals and industrial effluents in water bodies are major contaminants pollute water with nitrates, metals and pesticides
RAJESH NAYAK NATURAL VEGETATION AND WILDLIFE Rain water harvesting is the process of collecting rain water from roof tops and directing it to an appropriate location and storing if for future use.
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