2The changing EarthThe surface of the Earth is always changing.
3The Rock cycleThe rock cycle shows how rocks change back and forth between sedimentary, igneous, and metamorphic rocks.
4The rock cycle - Igneous Igneous rocks form when melted rock cools and solidifies.The crystal size in an igneous rock is determined by how fast the rock cooled.How fast the rock cooled is determined by how close to the surface the rock was, and how large the chamber was.Igneous rocks can be extrusive or intrusive
5The rock cycle - Igneous Examples of igneous rocks include:ObsidianGraniteBasaltPumiceRhyolite
6The rock cycle – Sedimentary Sedimentary rocks are formed by weathering, erosion, deposition, compaction, and cementation of other rocks.
7The rock cycle – Sedimentary Examples of sedimentary rocks include:SandstoneLimestoneFlintShaleCoal
8The rock cycle – metamorphic Metamorphic rocks form when heat and pressure deep beneath earth’s surface cause one type of rock to change into another type of rock.
9The rock cycle – metamorphic Examples of metamorphic rocks include:Gneiss (from Granite)Quartzite (from Sandstone)SchistSlate (from Shale)Marble (from Limestone)
10Energy in the rock cycle What types of energy are needed to form each type of rock?IgneousmetamorphicSedimentary
11Rock cycleHeat energy is important in the formation of igneous and metamorphic rocks.Where does that heat come from?
12Heat energy The earth gets hotter the deeper down you go, but why? Radioactive decay
13Kinetic energySome of the heat energy in the mantle is transformed into kinetic energy in the form of convection currents that form in the mantle.
14Kinetic energyConvection currents move the plates of the crust back and forth.A place where 2 plates meet is called a fault.
15Kinetic energy Potential energy Kinetic energy of the moving plates can be converted into potential energy when two plates collide and “stick” together.The potential energy builds up until it is finally converted back into kinetic energy and the plates “slip”
16Plate boundaries Plates that pull apart are called divergent plates Plates that push together are called convergent platesPlates that slide past each other are called transform plates.What do you think would happen to the earth at each type of boundary?
17Plate movementAs plates slide over, under, or past each other, they change the surface of the earth.
18Plate movementPlates that push together can cause the earth to “crumple” and form mountains.
19Plate movementWhen continental and oceanic plates collide, they can produce volcanoes.
20Plate movementWhen plates “slip”, “smash” or “pull” apart they produce earthquakes.During an earthquake, potential energy is converted to kinetic energy.(Remember that this mechanical energy started as heat energy inside the earth.)
21Plate movementSome of the heat energy from the earth reaches the surface (as in a volcano.)Some heat energy is transformed into mechanical energy in the form of convection currents, moving plates, earthquake waves, flowing lava, etc…
22Energy to infinity and beyond! Earthquakes, volcanoes, and mountain formation all occur when the heat energy from inside the earth makes its way to the surface. (Either as heat energy or mechanical energy.)
23Energy to infinity and beyond! Earthquakes and volcanoes can change earths surface very rapidly.Mountains building is a slow and gradual process that changes earths surface.These changes all occur because energy from earths interior transfers to the earth’s surface.
24Changes to Earth’s surface Some changes to the Earth’s surface are not caused by energy from the interior of the earth.These changes can come from weathering, erosion, deposition, gravity, glaciers, and other “agents” of change.
25WeatheringWeathering occurs when rock on the surface of the earth breaks down into smaller pieces.Weathering can be mechanical or chemical.
26Mechanical Weathering Mechanical weathering is when mechanical energy creates weathering. This mechanical energy could come from:Moving water/wind (abrasion)Freezing iceBurrowing animalsGrowing plant roots
27Chemical weatheringChemical weathering occurs when chemical energy causes weathering to occur.Things that could cause chemical weathering include:Acid rainOxygen (oxidation)Living things making acids to break down rock. (like lichens)
28Erosion and deposition Erosion occurs when water, wind, or ice move weathered rock particles from one place to another.Deposition is when those particles being carried by erosion get laid down somewhere.
29Weathering, erosion, and deposition Weathering, erosion, and deposition are important parts in the process of soil formation.
30GravityGravity changes the surface of the earth. Particles that weather and erode in the mountains get carried to the valleys.Gravity moves particles and sediment downhill.
31GravityGravity can cause several types of “mass movement” downhill including:LandslideMudflowSlumpCreep
32Gravity – Mass movement Landslides occur when rock and soil move quickly down a slopeMudflows occur when water, rock, and soil move downhill. (Usually during heavy rain.)
33Gravity – Mass movement Slumps occur when an entire section of a hillside suddenly slides down a slope but stays together.Creeps occur when rock and soil moves downhill very slowly.
34GlaciersGlaciers move slowly across the land. As they move, they shape the land in many ways.
35Glaciers Glaciers create features in the earth such as: U-shaped valleysCirquesHornsDrumlins
36Weathering Erosion and Deposition Weathering, erosion deposition and gravity can change the surface of the earth gradually or rapidly.
37Rapid changeFlash floods, landslides, mudflows, earthquakes, volcanoes can all change the earth rapidly.
38Gradual changeMountain formation, mountain destruction, weathering, erosion, creep, and glacial activity are all gradual changes to earth’s surface.
39Mountain buildingThe average mountain that is actively being built is moving upward at a rate of 6 mm/year and being eroded downward at a rate of 1 mm/year.A mountain that takes 5 million years to build might take 100 million years to erode away.
40Mountain buildingAs a mountain erodes away, the roots of the mountain push upward.For every 5 mm of the mountain that erode away, the roots push up 4 mm.The taller the mountain, the faster erosion occurs.