Understanding Rocks Earth and sky, woods and fields, lakes and rivers, the mountain and the sea, are excellent schoolmasters, and teach some of us more than we can ever learn from books. John Lubbock A self guided tour links Credits Start the tour About The Teacher Mr. Stephens Employer: Brandywine Heights Area School District Address: 200 W Weiss St. Topton PA Job Title: 8 th Grade Earth/Space Science Teacher Phone: (610) Hours of Work: 7:30am until 3:00 pm previous Self portrait The Rock Cycle The Rock Cycle The process by which one rock type changes into another. Each rock is classified by texture, composition and color. texture compositioncolortexture compositioncolor IgneousSedimentary Metamorphic Additional info previous Credits Background slide oneformations_8244.jpg Background slide oneformations_8244.jpghttp://www.alaska-in-pictures.com/data/media/22/lava-rock- formations_8244.jpghttp://www.alaska-in-pictures.com/data/media/22/lava-rock- formations_8244.jpg Credit buttonCredit buttonHome buttonoshop-website-home-button-icon36-thumb.gif Home buttonoshop-website-home-button-icon36-thumb.gifoshop-website-home-button-icon36-thumb.gifoshop-website-home-button-icon36-thumb.gif The Rock CycleThe Rock CycleAdditional Info slide 4Additional Info slide 4Igneous rock slide 4jpg Igneous rock slide 4jpgjpgjpg Metamorphic rock slide 4Metamorphic rock slide 4Sedimentary rock slide 4Sedimentary rock slide 4Sedimentary rock formation slide 5Sedimentary rock formation slide 5Igneous Formation slide 7Igneous Formation slide 7Granite slide 9Granite slide 9 previousnext Additional Credits Additional Credits DioriteDioriteGranite samplesGranite samplesRhyoliteRhyoliteBasaltBasaltAndesiteminerals/images/andesite.jpg Andesiteminerals/images/andesite.jpghttp://www.otago.ac.nz/geology/research/general_geology/rocks- minerals/images/andesite.jpghttp://www.otago.ac.nz/geology/research/general_geology/rocks- minerals/images/andesite.jpg Fine grained siltstoneFine grained siltstoneSandstoneSandstoneTemperature and pressure graphTemperature and pressure graphContact metamorphism drawingContact metamorphism drawingContact metamorphism imageContact metamorphism imageCliff erosionCliff erosionDepositionwater/deposition-sediments.jpg Depositionwater/deposition-sediments.jpghttp://www.belmont.sd62.bc.ca/teacher/geology12/photos/erosion- water/deposition-sediments.jpghttp://www.belmont.sd62.bc.ca/teacher/geology12/photos/erosion- water/deposition-sediments.jpg previous Sedimentary Rocks Rocks that form when sediments are compacted and cemented together. previousnext Sedimentary rock Formation Grains of sand and sediment eroded by weathering Grains of sand and sediment eroded by weathering Form thick layers that are eventually cemented together Form thick layers that are eventually cemented together Commonly formed on the ocean floor and other low areas Commonly formed on the ocean floor and other low areas The most common rock found on the Earths surface The most common rock found on the Earths surface previousnext Weathering Notice the erosion taking place on the face of the cliff. The material collecting on the beach will eventually turn into a sedimentary rock. previousnext Deposition Eroded materials that are carried by water are eventually deposited in ponds, lakes or oceans. Particles are deposited according to size. previous Texture The texture is determined by the size and shapes of the rocks grains The texture is determined by the size and shapes of the rocks grains Fine grained silt or clay particles Fine grained silt or clay particles Fine grained Fine grained Medium Grained sand Medium Grained sand Medium Grained Medium Grained Coarse Grained pebbles Coarse Grained pebbles Coarse Grained Coarse Grained previous Fine grained Fine grained siltstone previous Notice how difficult it is to see each mineral particle. In fine grained rocks the gains are tightly packed together. Medium Grained If you look closely you can see the different rock grains that make up this rock. Sandstone previous Coarse Grained Bits and pieces of pebbles and rocks naturally cemented together. Notice how much larger the particles are compared to the medium and fine grained samples. Coarse grained conglomerate previous Clastic Sedimentary Rocks Rock fragments are compacted and cemented together Rock fragments are compacted and cemented together Classified according to grain size Classified according to grain size Coarse-grained to fine-grained Pebbles, sand, silt and clay Conglomerate Sandstone Siltstone Shale Chemical Sedimentary Rocks Form from solutions of minerals in water Form from solutions of minerals in water Minerals can precipitate out of water solution Minerals can precipitate out of water solution Chert Rock SaltLimestone Dolomite Organic Sedimentary Rocks Coal Coquina Chalk Formed by the accumulation of organic debris Formed by the accumulation of organic debris Plant and animal material Plant and animal material Metamorphic Rocks Rocks that forms when the texture and composition of a preexisting rock changes by heat and pressure produced deep within the Earth previousnext Metamorphic Rocks cont. Metamorphic rocks are formed deep within the Earth Metamorphic rocks are formed deep within the Earth Meta in Latin means change Meta in Latin means change Morph in Latin means shape Morph in Latin means shape Thus, metamorphic means a physical change due to heat and pressure. Thus, metamorphic means a physical change due to heat and pressure. previousnext Contact Metamorphism When surrounding rock comes in contact with magma but do not melt they often change to harder metamorphic type rocks. previousnext More contact metamorphism The lava flow at the top of the picture has baked the mud beneath it into brick- red shale. This is an ideal case of contact metamorphism. previousnext Regional Metamorphism Regional metamorphic rocks are rocks that are altered in composition and texture due to: Regional metamorphic rocks are rocks that are altered in composition and texture due to: extreme heat and pressure over a large area extreme heat and pressure over a large area during mountain formations or subduction during mountain formations or subduction previousnext Heat and Pressure Relationship As temperature increases less pressure is needed. As pressure increases less temperature is needed. previous Igneous Rocks Rocks that form from cooling of magma and lava both inside and on the surface of the Earth. Rocks that form from cooling of magma and lava both inside and on the surface of the Earth. previousnext Introduction to Igneous Rocks Video Clip Igneous Rocks Igneous comes from the Latin word for fire Igneous comes from the Latin word for fire Intrusive forms when magma cools below the Earths surface Intrusive forms when magma cools below the Earths surface Intrusive Intrusive Extrusive forms from lava cooling on the surface of the Earth Extrusive forms from lava cooling on the surface of the Earth Extrusive Extrusive previousnext Intrusive Intrusive igneous rocks form when magma cools slowly below the Earth's surface. Intrusive igneous rocks form when magma cools slowly below the Earth's surface. Most intrusive rocks have large, well-formed crystals.Most intrusive rocks have large, well-formed crystals. Examples include granite, gabbro, and diorite. Notice how each sample has large crystals that are easily seen. Examples include granite, gabbro, and diorite. Notice how each sample has large crystals that are easily seen.granitegabbro dioritegranitegabbro diorite previousnext Extrusive Extrusive igneous rocks form when magma reaches the Earth's surface cooling quickly to form lava. Extrusive igneous rocks form when magma reaches the Earth's surface cooling quickly to form lava. Most extrusive (volcanic) rocks have small crystals. Most extrusive (volcanic) rocks have small crystals. Examples include basalt, rhyolite, and andesite. Examples include basalt, rhyolite, and andesite.basaltrhyoliteandesitebasaltrhyoliteandesite previous Basalt Rhyolite Andesite Composition The minerals a rock is made of determines its composition. The minerals a rock is made of determines its composition. Example Granite typically has 10% Biotitie Mica, 35% Quartz and 55% Feldspar. Example Granite typically has 10% Biotitie Mica, 35% Quartz and 55% Feldspar. Different classifications of Granites can have different amounts of each of these minerals. Different classifications of Granites can have different amounts of each of these minerals. previousnext Composition cont. Notice: each sample varies but they are all part of the same (granite) family of rocks. previous Colors often vary due to impurities found within the rock. Below is good example of color variations. Rocks which are relatively high in heavier elements Rocks which are relatively high in heavier elements Mafic minerals are usually dark in color Mafic minerals are usually dark in color The term is derived from The term is derived from MA from magnesium MA from magnesium FIC from the Latin word for iron FIC from the Latin word for iron Mafic Rocks previousnext Felsic Rocks Felsic rocks have low percentage of heavier elements Felsic rocks have low percentage of heavier elements Felsic rocks are light in color Felsic rocks are light in color Higher percentage in lighter elements such as silica and oxygen Higher percentage in lighter elements such as silica and oxygen The term comes from The term comes from FEL for feldspar FEL for feldspar SIC which indicates the higher percentage of silica SIC which indicates the higher percentage of silica previous Granite Gabbro Diorite Coal Video Clip:etowpath/Bookshelf/Coal/etowpath/Bookshelf/Coal/ Limestone Video Clip:etowpath/Bookshelf/Limestone/etowpath/Bookshelf/Limestone/ Slate Video Clip:etowpath/Bookshelf/Slate/etowpath/Bookshelf/Slate/