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 one formations_8244.jpg Background slide one formations_8244.jpghttp:// formations_8244.jpghttp:// formations_8244.jpg Credit button Credit button Home button oshop-website-home-button-icon36-thumb.gif Home button oshop-website-home-button-icon36-thumb.gif oshop-website-home-button-icon36-thumb.gif oshop-website-home-button-icon36-thumb.gif The Rock Cycle The Rock Cycle Additional Info slide 4 Additional Info slide 4 Igneous rock slide 4 jpg Igneous rock slide 4 jpg jpg jpg Metamorphic rock slide 4 Metamorphic rock slide 4 Sedimentary rock slide 4 Sedimentary rock slide 4 Sedimentary rock formation slide 5 Sedimentary rock formation slide 5 Igneous Formation slide 7 Igneous Formation slide 7 Granite slide 9 Granite slide previousnext

Additional Credits Additional Credits Diorite Diorite Granite samples Granite samples Rhyolite Rhyolite Basalt Basalt Andesite minerals/images/andesite.jpg Andesite minerals/images/andesite.jpghttp:// minerals/images/andesite.jpghttp:// minerals/images/andesite.jpg Fine grained siltstone Fine grained siltstone Sandstone Sandstone Temperature and pressure graph Temperature and pressure graph Contact metamorphism drawing Contact metamorphism drawing Contact metamorphism image Contact metamorphism image Cliff erosion Cliff erosion Deposition water/deposition-sediments.jpg Deposition water/deposition-sediments.jpghttp:// water/deposition-sediments.jpghttp:// 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 Earth’s surface The most common rock found on the Earth’s 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 rock’s grains The texture is determined by the size and shapes of the rock’s 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 Earth’s surface Intrusive – forms when magma cools below the Earth’s 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/