Unit 2 Weathering Erosion Vocabulary Weathering Mechanical physical
Unit 2: Weathering & Erosion
Vocabulary ✦ Weathering ✦ Mechanical (physical) weathering ❖ oxidation ✦ Chemical weathering ❖ p. H scale ✦ agents of erosion ❖ Acid ✦ erosion ❖ Base ✦ deposition ✦ ice wedging ✦ surface area ❖ permeable ❖ climate
Weathering and Its Effects ✦ Weathering is the surface processes that work to break down rock ✦ Rocks are broken down into smaller particles called sediments. ✦ Sand- grains larger than silt ✦ Silt- grains larger than clay ✦ Clay- smallest sediment grains ✦ Over millions of years, weathering has changed Earth’s surface ✦ Mountains become hills
Mechanical (physical) and Chemical Weathering Mechanical weathering (left) occurs when rocks are broken apart by physical processes. Chemical weathering (right) occurs when chemical processes dissolve or alter (change) the minerals in a rock or change them into different minerals.
Mechanical (physical) weathering ✦ After a rock has been physically weathered ✦ overall chemical makeup remains the same ✦ Each sediment has similar characteristics to the original rock ✦ Ex. Growing plants ✦ Burrowing animals ✦ Ice expanding
Plants and Animals
Ice (frost) Wedging ✦ Ice wedging occurs in temperate and cold climates where water enters cracks in rocks and freezes ✦ Freezing expands, causing the rock to crack
Chemical Weathering ✦ After a rock has been chemically weathered: ✦ chemical composition of the rock is different ✦ rock can be weakened ✦ Ex of agents of erosion: ✦ acid rain ✦ living organisms ✦ carbon dioxide ✦ water ✦ oxygen
Chemical Weathering Agents Living organisms Oxygen + Iron
Oxidation ✦ Oxidation- when iron combines with oxygen in the presence of water ✦ Ex. iron chains turn into rust ✦ creates a new material and usually gives rocks or objects a reddish-orange color
Erosion ❖ Once rock is weathered and broken down, the smaller pieces are carried away by wind, water, ice, or gravity (agents of erosion) ❖ Erosion- process of bits of broken rock being carried away ❖ Deposition- when agents of erosion deposit or lay down sediment ■ changes land
Surface Area ✦ Surface area- area of a rock or other object that is exposed to the surroundings ✦ As mechanical/physical weathering occurs, rocks are broken down into smaller and smaller particles ✦ smaller pieces have more surface area, exposing more of the rock to water and oxygen ✦ increase in surface area speeds up chemical weathering
p. H Scale ✦ p. H scale-used to measure the strength of acids and bases ✦ (1 -14) ✦ low p. H = acidic ✦ high p. H = basic ✦ Acids: chemical liquids with a lot of hydrogen ions ✦ Bases: chemical liquids with a lot of hydroxide ions ✦ Most minerals dissolve easier in more acidic soil ✦ Different plants also grow best in certain p. H values
p. H Scale
Effects of Climate ✦ Climate- pattern of weather that occurs in a particular area over many years ✦ cold climates- mechanical weathering breaks down rocks very quickly through ice wedging. ✦ warm, moist climates- chemical weathering is more common
Effects of Rock Type
Rock ❖ Permeable- material is full of tiny, connected air spaces that allow water into it
Videos ✦ https: //www. youtube. com/watch? v=R-Iak 3 Wvh 9 c ✦ https: //www. youtube. com/watch? v=ex. S 9 g. FXgib 0 ✦ https: //www. youtube. com/watch? v=ysg. Zog. SBMio ✦ https: //www. youtube. com/watch? v=6_e 5 CGBZXZs
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