Full Geography Handout - Sem 1 - Grade 8 PDF
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This document is a geography handout covering various topics related to rivers and coasts. It discusses weathering, erosion, agents of erosion, types of weathering, and coastal landforms.
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ull Geography Handout - Sem 1 - F Grade 8 Index: 1. Ch.1 - Rivers and Coasts 2.Ch.2 - Economic Activity 3.Ganga River case study Chapter 1 - Rivers and Coasts Weathering and Erosion: 1.Weathering is the breaking up of rock into smaller pieces by wind, water,...
ull Geography Handout - Sem 1 - F Grade 8 Index: 1. Ch.1 - Rivers and Coasts 2.Ch.2 - Economic Activity 3.Ganga River case study Chapter 1 - Rivers and Coasts Weathering and Erosion: 1.Weathering is the breaking up of rock into smaller pieces by wind, water, temperature, chemicals, plants, and animals.(Agents of weathering) 2.Erosion is the transportation of the broken rock from one place to another and in the process, there is further breaking down of the material. Agents of Erosion: Wind:Wind carries sand particles with it when itblows. While carrying this, it rubs against each other, breaking it down further. This process is called erosion Rivers:Rivers erode/wear away tiny bits of rock fromtheir channel bed. This material is carried downstream and deposited when the water slows down. In times of a flood, large boulders are loosened and rolled down the river bed. Sea:During storms, each wave hits a rock with a weightof several tonnes. When this is repeated many times, the rock is weakened and pieces break off. Currents carry loose materials away and deposit them elsewhere. How does Erosion help shape the land? Erosion wears away the land, transportation moves the material from one place to another, and deposition builds up new landforms. Types of Weathering: 1. Freeze and Thaw Weathering: - It is also known as frost-shattering - Water may get into a crack in a rock and freeze - Ice causes the crack to expand or widen - When the ice thaws it turns back into water - Repeated freezing and thawing weakens the rock - Eventually, the rock breaks up into small pieces - This type of weathering is mainly found in mountainous areas with freezing temps. 2. Onion Skin/Peel Weathering: - This takes place in deserts where days are hot, and nights are cold. - During the day the heat makes the outer layer of the rock expand and at night the cold makes the outer layer of the rock contract. - Over time, Repeated heating and cooling weakens the rock which causes it to peel off like an onion - This peeling off of layers of rock is referred to as onion skin weathering. 3. Biological Weathering: - This typically happens in rainforests - Seeds might fall into rock cracks - Due to moisture, The seed grows into a tree, whose roots break up rock - This is also caused by burrowing animals like earthworms, which weaken rocks and break them up over time. - Sometimes, microorganisms also break up rocks. A lichen is a symbiosis b/w an algae and a fungus. Minerals produced by microorganisms break down rocks. These minerals are then eaten by alga, which further cause rocks to crack and break apart. 4. Chemical Weathering: - Happens in warm and wet places. - Rainwater has chemicals and acids in it. (hydrolysis, oxidation, and carbonation) - It reacts with the chemicals of the rock and rots and crumbles over a long time. 5. Wind Weathering: - It only happens in windy places - The wind carries small sand particles with it - When the wind hits rocks in its path, it abrades. (sandpaper effect) - Over time, it polishes, weathers, and even rotates the rock. Waterfalls and Valleys: V-Shaped Valley - Spurs: Ridges of land which a river winds -Valley Sides:The slopes on either side of a river -V-Shaped Valleys:The shape of a valley in its upper course - River Channel: The course of a river -River Banks:The sides of a river channel - River Bed:The bottom of a river channel - Load:Material that is carried by the river Waterfalls and Valleys: Waterfall At the bottom of a cliff, the water has worn away the soft rock to form a plunge pool. A gorge is a valley with almost vertical sides carved out by the river and waterfall. Cross section of a River Bend: Asteep bankon the outside of a river bend that's created by erosion over time is called a river cliff Across-sectionis a view across a landform like a river at right angles. It is what the river would look like if a slice were cut across it from one side to the other The flow of water in a certain direction is acurrent A meander is a large bend in a river A flood plain is a flat land at the bottom of a river valley which is often flooded. They are useful for farming because they are flat and have fertile soil. Alluvium/Silt is a fine mud-like material left behind after a flood. (often found in flood plains) Ox-Bow Lake Erosional and Depositional Landforms: Erosion landforms are made by wearing away the coast. Depositional landforms are formed when material worn away from one part of the coast is carried away and dropped somewhere else. In stormy conditions, the sea picks up loose rocks and throws them at the shore, this undercuts cliffs, this breaks up loose rocks into smaller and smaller pieces. Areas which have soft rocks are worn away more easily than those with hard rocks. The soft rock areas will become bays, and the hard rock areas will become headlands. A bay is an opening in the coastline and the headlands are pieces of land jutting out toward the sea. A beach is an example of a depositional landform. A Spit is a special type of beach extending out into the sea It is caused by a wind known as ‘longshore drift’ Made by constructive waves What are the Coastal Erosional Problems? Coastal Erosion can cause severe problems (like not getting unreal) Agricultural loss, buildings destroyed, and transport links are put in danger. The Holderness Coast problems and solutions: Many people in the Holderness area worry about their future(like Clipz&Ice bc them no winning in FnCs) They fear losing their homes and in some cases, their livelihoods. Several farms are threatened and seaside resorts like Hornsea and Withernsea, where many people work are also in danger. How can Coastal Erosion be Reduced? 1. Sea Walls - Sea walls stop waves from reaching the land. - They reflect the waves into the ocean. - They are very expensiveandtake much time and effort to repair. 2. Beach Rebuilding - This replaces the lost sand from the beach using tractors. - The beach absorbs wave energy and is a good defence against the sea. - It protects the land and the sea wall behind it. - It makes the beach look more natural. - It is the most efficient. - While the process is happening, the beach cannot be used. - Expensive - Requires repeated application 3. Groynes - These are built down the beach 200m apart. - They slow down the movement of material moving along the coast and help build up the beach. - The beach then helps protect the land. - They can be unattractive 4. Rip-Rap - A mixture of large boulders and rocks - It is the least expensive - It protects the coast by breaking up the waves - They don't protect cliffs as well as a sea wall - They can look ugly
