Presentation on theme: "BIOGEOCHEMICAL CYCLES"— Presentation transcript:
1BIOGEOCHEMICAL CYCLES Everything goes around and around and around ……………………….
2Law of Conservation Matter cannot be create or destroyed It simply changes formsBottom line is there is a fixed amount of stuffWe’re not making any more atoms (elements)They move around the systemsWhere they are located in the system effects the system
3An Amazing ThoughtWhile the things made up of the atoms may be young, you for example, the atoms that you are made of have been around since the beginning of the universe.Your atoms could have been part of an ancient tree, or a dinosaur!Kind of weird isn’t it?
4Plate Tectonics and the Rock Cycle The rock cycle is the result of earth moving matter (rocks and minerals) via plate movement (plate tectonics)The atoms that make up rocks and minerals start out in the mantle and eventually end up back in the mantleLets take a look.
5Rocks Two or more elements combine to make minerals Two or more minerals combine to make a rockThere are three types of rocksIgneous rocks form from cooled magmaSedimentary rocks are pieces of minerals or organic material cemented togetherMetamorphic rocks are formed when either igneous or sedimentary rocks are subjected to enormous heat and pressure
6Igneous rocks Magma is molten rock inside the earth Think of it like a molten elemental soupDoes magma have a lot of energy or a little energy?What does that tell you about the motion of the atoms in the magma?
7CoolingAs energy leaves the magma, the atoms slow down enough to begin to bondThey arrange themselves into regular patternsThe rate of cooling determines the size of the crystal patterns in the rockWould you expect magma inside the earth or out on the surface to cool faster?
8Plutonic or Intrusive Rock Magma inside the earth loses energy slower than magma on the surfaceThe elements have more time to form mineral crystalsSubsequently, the mineral crystals are bigger in intrusive igneous rock formed by cooling magma below the surface
9Volcanic or Extrusive Rock Magma that comes to the surface is called lavaIt cools considerably fasterSubsequently, extrusive rock lacks the distinct mineral crystals / grains found in plutonic rockIt is still made of the same elements
10WeatheringAs soon as rock is exposed to earth’s surface, it is exposed to processes that break it back down into individual mineral crystals (we typically refer to them as sand)This process is called weatheringThere are two types of weathering, mechanical and chemical
11Mechanical Weathering Mechanical weathering or disintegration occurs when the rock is broken into progressively smaller pieces without changing it’s chemical compositionThis is PHYSICAL changeI have the same basic mineral crystals I’m just breaking them into smaller piecesExample:Beating a rock into sand with a hammer
12Causes of Mechanical Weathering Wetting and dryingFreezing and thawing (Ice wedging)Plant rootsContact with other rocksRock slides or avalanchesWashing down rivers
13Chemical WeatheringIn chemical weathering the agent essentially changes the mineral crystal into something elseThis is CHEMICAL changeThe resulting substance no longer looks like or has the same properties it did before
14Chemical Change Agents HydrolysisWater combining with the mineralsOxidationOxygen combining with the mineralsCarbonic AcidCarbon dioxide combining with water then dissolving the minerals
15ErosionAll these big and little pieces of weathered rock (sediments) can be moved by the wind and waterThis is the process of erosion, the movement of sediments from one place to another
16DepositionEventually the speed of the wind or water carrying sediments slows and it cannot support the weight of the sedimentsThe sediments fall and begin to stack up in layersThis is called depositionAs the wind or water slows, which size sediments will fall out first and which last?
18Sedimentary RockAs the sediments and the remains of living organisms get buried deeper, they can become cemented together to form sedimentary rockClastic: Formed from cemented pieces of other rocksOrganic: Formed from the remains of plants and animals
19Metamorphic RocksRocks that are formed from other rocks when they are exposed to enormous heat and pressureIgneous or sedimentary rock that has been exposed to enormous heat and pressure (for example at plate boundaries) literally gets squished becoming denser and changing appearance
20The Rock CycleThe movement of elements through this system is called The Rock Cycle
21Elemental SoupMagma cools allowing the elements to slow down and start to bond1or more elements combine to make minerals, 2 or more minerals combine to make rockThe slower magma cools the bigger the crystals
22WeatheringAs soon as the rock is exposed at the surface, it comes under attackWind, water and chemicals are the enemyThese agents break the rock down physically or chemically
23ErosionThe rock particles are carried off by the wind and water to be deposited
24Sedimentary Rock The sediments pile up over time As the sediments are buried they can become cemented together becoming sedimentary rock
25Metamorphic RocksIgneous RockAnywhere Igneous or Sedimentary rocks are exposed to enormous heat or pressure they can be turned into metamorphic rocksSedimentary rockMetamorphic Rock
28Some Things to Remember The process takes thousands or millions of yearsThere is no set pattern to the process. Metamorphic rocks can be uplifted and weathered etc.The bottom line is the elements that start in the magma eventually end up back there.