2 WeatheringWeathering is the process that breaks down rock and other substances at Earth’s surface.
3 ErosionErosion is the movement of rock particles by wind, water, ice, or gravity.
4 Working togetherWeathering and erosion work together continuously to wear down and carry away the rocks at Earth’s surface. Weathering breaks rock down and erosion carries it away.
5 2 Types of Weathering There are 2 types of weathering: Mechanical and Chemical
6 Working togetherAs mechanical weathering breaks rock into pieces, more surface area becomes exposed to chemical weathering. So, they also work together.
7 Mechanical Weathering The type of weathering in which rock is physically broken into smaller pieces is called mechanical weathering.
8 Agents of mechanical weathering Freezing and thawingRelease of pressureAction of animalsGrowth of plantsAbrasion - rock particles carried by wind, water, ice and gravity.Water expands when it freezes, and acts as a wedge.This process is called ice wedging.
11 Chemical WeatheringChemical weathering is the process that breaks down rock through chemical changes.
12 Agents of chemical weathering The agents of chemical weathering include:waterOxygen (oxidation is a reaction w/ O2)carbon dioxide ( carbonic acid)living organisms( plant roots produce weak acids)acid rain
14 Rates of weatheringThe most important factors that determine the rate at which weathering occurs are the type of rock and climate.Ex: Some rock weathers easily because it is permeable, which means that it is full of air spaces that water gets through.
15 Chemical weatheringWater is the most important agent of chemical weathering.Water weathers rock by dissolving it.The oxygen in air is an important cause of chemical weathering.Plant roots produce weak acids that slowly dissolve any rock around the roots.Lichens also produce a weak acid that weathers rock.Acid rain causes very rapid chemical weathering.
16 Erosion The material moved by erosion is sediment. When the agents of erosion lay down sediment, deposition occurs.Deposition changes the shape of the land.
19 Cycle of erosionWeathering, erosion, and deposition act together in a cycle that wears down and builds up Earth’s surface.Erosion and deposition are at work everywhere on Earth. Sometimes, they work slowly. At other times, they work more quickly.
25 Glacial ErosionCaused by gravity pulling glacier down
26 Wind Erosion Wind itself is the weakest cause of erosion. Greatest impact is on an area that has few plants to hold dry soil in place
27 Gravity is the force that moves rock and other materials downhill. Gravity causes mass movement, any one of several processes that move sediment downhill.Mass movement can be rapid or slow.
28 Mass Movements The different types of mass movement include: Landslides – rock and soil slide quickly down a steep slope.Mudslides -the rapid movement of a mixture of water, rock, and soil.Slump – a mass of rock and soil suddenly slips down a slope in one large mass.Creep – very slow downhill movement of rock and soil.
39 Catastrophic events can affect Earth in several ways. Catastrophic events that result from surface processes may speed up erosion and deposition.Catastrophic events resulting from processes inside Earth change the crust itself (volcanoes).
40 People, People, PeopleWhere people locate their activities can increase the damaging effects of natural hazards.How people use land also alters Earth systems in ways that may cause catastrophic events.