Presentation on theme: "ROCKS NJCCCS: 5.4 C – Properties of Earth Materials"— Presentation transcript:
1ROCKS NJCCCS: 5.4 C – Properties of Earth Materials Chapter 3ROCKSNJCCCS: 5.4 C – Properties of Earth Materials
2What is a Rock?A mixture of minerals, mineraloids, glass, or organic matterex. Granite = mica + quartz + feldspar + hornblende + other minerals
33 Rock Types Igneous Rocks – form from cooling magma or lava Metamorphic Rocks – form from extreme heat and pressureSedimentary Rocks – form from the compaction and cementation of sediment (rock fragments)
4Other Key Terms Magma: molten rock inside the Earth Lava: molten rock on the surface of the EarthSediment: smaller pieces of rock (rock fragments)Weathering: breaking rocks into sedimentErosion: moving sediment from one location to anotherCompaction and Cementation: process of squeezing and gluing sediment into a sedimentary rock
6Igneous RocksIgneous Rocks - cooled molten material form the inside the Earth(magma) or out of a volcano (lava)- the most common rock on Earth
7Igneous RocksB. The Earth’s crust generates great temps (1400), pressures, and radioactive thermal energyC. Rocks and Minerals melt to form magma, minerals have different densities and melting pts
8Igneous RocksD. Magma is less dense than the crust above and forces an escape through volcanoes as lavaE. Sometimes magma forces upwards but cools before reaching the surface
9Classification of Igneous Rocks (1) Intrusive Igneous Rocks - those rocks that were formed from cooling magma below the Earth’s surfaceCool very slowlyHave large crystals called mineral grainsExtrusive Igneous Rocks - Rocks that formed from cooling lava on the surface of the Earth-Cool very quickly- Have very fine grained texture
10IGNEOUS ROCKS – cooled magma or lava Intrusive igneous rocks have large mineral grains!!!!!Extrusive igneous rocks have virtually no mineral grains.
11Classification of Igneous Rocks (2) 1. Basaltic – dense, heavy, dark colored rock, rich in magnesium and iron, most common2. Granitic – light color, less dense, rich in silicon and oxygen3. Andesitic – mineral compositions in between the two, common among Pacific Volcanoes
14(Plutonic) Intrusive Igneous Features Magma Chamber is a large underground pool of molten rock found beneath the surface of the Earth.
15Intrusive Igneous Features Sill is an intrusion of magma that solidifies into a horizontal layer of igneous rock
16Intrusive Igneous Features Dike is a magma that cuts across rock layers (vertical)
17Intrusive Igneous Features Batholith is a magma chamber that cools before reaching the surface to form a volcano
18Intrusive Igneous Features Laccolith is a small magma chamber at shallow depth (roughly lens shaped)
19Extrusive Igneous Features Volcano is an opening, or rupture, in a planet's surface or crust, which allows hot magma, volcanic ash and gases to escape from below the surface3 types:ShieldCompositeCinder
20Extrusive Igneous Features Lava Flow – different types of lava depending on the composition and temperature
21Extrusive Igneous Features Ash and Dust Particles
22Extrusive Igneous Features Pyroclastic Flow is a fast-moving current of extremely hot gas ( 1,830 °F) and rock which travel away from a volcano at speeds generally as great as 450 mph.
23Sedimentary Rocks 3 Types of Sedimentary Rocks 1) Clastic – made from rock fragments2) Chemical – evaporation or precipitation from solution3) Organic – contains fossils
24Classification of Sedimentary Rocks 1) ClasticMade from sediments
37Organic Sedimentary Rock Coal – formed from theRemains of plants at theBottom of a body of waterLimestone – formed from the mixed skeletal remains of marine organisms
38Chemical Sedimentary Rock Gypsum – easily dissolves in water… gypsum rock forms when the water evaporates and crystallizesHalite – (salt) – easily dissolves in water…halite forms when salt water evaporates and crystallizes
40Metamorphic RocksMetamorphic Rocks - rocks that have changed due to increases in temperature and pressure (the minerals inside them change shape and alignment)- igneous, sedimentary, metamorphic rocks can metamorphB. Ex. Basalt Schist GneissShale Slate Phyllite GneissGranite Gneiss
41Occurs in 2 general ways: 1) Contact Metamorphism Metamorphic RocksOccurs in 2 general ways:1) Contact Metamorphism2) Regional Metamorphism
42Contact MetamorphismAs magma pushes through rock layers beneath the Earth…nearby rock change slightly in composition and structure
43Regional Metamorphism As the Earth’s plates move, the same extreme pressures that build mountains also cause rocks to deform and change in composition
44WHAT HAPPENS? Heat - (2 sources- magma and depth) Minerals within the rock melt and re-crystalize thus changing the composition of the rock
45WHAT HAPPENS?Pressure – causes space between minerals to close – compacted often causing minerals to recrystalize
462 classificationsFoliated – banded (layers) of minerals at 90 degree angles to the pressure that caused the metamorphismNon-Foliated – no bands or layers (usually composed of only one type of mineral)
47Metamorphic Rocks – HEAT AND PRESSURE FOLIATED = bands of mineral grainsNON-FOLIATED = no bands of mineral grains
50NJCCCS: 5.4B History of the Earth 5.4.12.B.1, 2, 3 FOSSILSNJCCCS: 5.4B History of the EarthB.1, 2, 3
51FossilsFossil - any naturally preserved evidence of past life
52Understanding Decomposition When an organism dies specialist organisms called decomposers and detritivores begin consuming its remains.Decomposers are usually bacteria and fungi (think sour milk and moldy bread)Detritivores are animals like vultures, hyenas, insect larvae, and a host of others (think maggots in a garbage can)Most often only the hard tissue of the organism is left behind… bones and teeth, shells, exoskeletons, etc.See Video clip – Blue Planethttps://www.youtube.com/watch?v=vQbGk4sHROg&noredirect=1
53Fossils Are RareFossils only form under very special environmental conditions!!!!!!!Usually found in sedimentary rocks…why?Exceptions: Volcanic ash
543 ways in which fossils form 1) Mineral Replacement2) Mostly Unchanged3) Trace
55Mineral ReplacementUnderground water removes original material 1 atom at a time and replaces it with minerals.An exact copy is created out of the minerals calcite CaCO3 or silica SiO2.*Most Common way in which fossils form3 basic types Petrification, Molds, Casts
561) Petrificationthe organism gets totally replaced with minerals
572) Moldsdead creature is covered with sediments and decays away. The remaining cavity in the shape of the original creature is the fossil = impression
583) CastMinerals from ground water seep into the mold, precipitate out of solution, and a stone shape is the fossil
59Mostly UnchangedActual original parts of an organism are left behind by several methods.1) Simple Burial2) Frozen3) Amber4) Mummification5) Acidic Peat Bogs6) TarSPECIAL ENVIRONMENTAL CONDITIONS EXIST THAT PREVENT DECOMPOSITION!!!!
601) Simple Burialbones and teeth most often remain…share similar properties to minerals (calcium carbonate)
612) Frozensoft parts of mammoths have been found in frozen arctic tundraWhy do we put food in a freezer?Slows down decomposition!!
623) Amberresin or ancient tree sap captured creatures (insects, frogs, etc.)
634) Mummificationcreatures desiccate (dry out) and soft parts remain – salt and or lye prevent decomposition
645) Acidic Peat Bogscreatures have been preserved in some wetlands that have environmental conditions that prevent decomposition (lack of oxygen, extreme pH)
656) Tarancient oil seeping from underground trapped creatures. La Brea Tar Pits in California hold bones of mammoths, sabretooth tigers, camels, and more. Tar prevented decomposition.
66Trace Fossil EvidenceEvidence of past life NOT including plant or animal remains