Igneous, Metamorphic, and Sedimentary Rocks

Igneous Rock  Igneous rocks come from two major sources: –Magma –Lava Who can explain the difference between the two? Magma comes is liquid rock beneath the surface, it becomes Lava when it reaches the surface of the Earth.

 Igneous rocks formed from magma are formed ________ (where?), and they are called plutonic, or intrusive igneous rocks.  Igneous rocks formed from lava are formed ________, and they are called volcanic, or extrusive igneous rock.

Two Major Types of Magma Felsic – Composition of mostly feldspar and silica. Slow moving, and solidifies as a hard grainy rock like Granite. Most plutonic rocks are Felsic. Felsic – Composition of mostly feldspar and silica. Slow moving, and solidifies as a hard grainy rock like Granite. Most plutonic rocks are Felsic. Mafic – High composition of magnesium and iron. It’s hotter, thinner and faster moving. Solidifies as a dark material like basalt. Mafic – High composition of magnesium and iron. It’s hotter, thinner and faster moving. Solidifies as a dark material like basalt.

Textures (An overview) Depends on size, shape, and arrangement of crystals. Depends on size, shape, and arrangement of crystals.  Examples: Obsidian – smooth and glossy. Granite is rough and grainy. The longer magma stays liquid, and the more gas that is trapped within it, the larger the crystals. (Example: The grains in Granite are crystals) Taking from what you just learned, what type of igneous rock do you think you’d find the largest crystals? Take a moment and talk it over with your table! Taking from what you just learned, what type of igneous rock do you think you’d find the largest crystals? Take a moment and talk it over with your table!

Sedimentary Rock Who can tell me what sedimentary rock is? Who can tell me what sedimentary rock is? –Sediments are: Formed by the hardening and cementing of layers of sediments. Consist of rock fragments, plant and animal remains, or chemicals that form on lake and ocean bottoms. Formed by the hardening and cementing of layers of sediments. Consist of rock fragments, plant and animal remains, or chemicals that form on lake and ocean bottoms. Where do the sediments come from? Where do the sediments come from? –Weathering is primary cause. They range in size; large pebbles to sand-like grain. Wind, waves, glaciers, rain, running water, etc.  What type of rocks could sediment come from?  Are sediments only made up of rock?

 3 types of Sedimentary Rock:  1) Clastic – Formed from fragments of other rocks. (Shale, Sandstone, conglomerate)  2) Chemical – formed from mineral grains that fall out of a solution, (precipitation), by evaporation or by chemical action. Rock salt and some limestone are examples.  3) Organic – rocks are formed from remains of plants and animals. Coal, and limestone made of shell fragments are examples

Formation of Clastic Sedimentary Rock  - They form via cementation by natural cement substances such as Calcite (CaCO3), iron oxide (FeO), or silica (SiO2).  - Sometimes, pressure is enough to bind together sediments.  You do not need to know CaCO3, FeO, or SiO2. Just be aware that there are natural cements.

Metamorphic Rocks Formed when rocks that already exist are changed by heat and pressure into new kinds of rocks. –Examples: Gneiss, slate, marble, quartzite –** Not formed by either magma or sediment!! ** Gneiss resembles granite, slate resembles shale, marble resembles limestone etc. The reason for these similarities is because the rocks that they resemble are the parent rock. - They are formed through the action of heat, pressure, and chemicals.

Types of Metamorphism Regional Metamorphism - happens over large areas. Plate tectonics are an excellent source of regional metamorphism. Shale: Rock becomes more dense and crystalline, forms slate. If the heat and pressure is more intense, it can create schist. Contact Metamorphism – Happens when magma forces its way into overlaying rock. The heat of it bakes the rocks that are in contact with it. The hot liquids and gases can enter into the rock and react with the minerals therein. Contact Metamorphism – Happens when magma forces its way into overlaying rock. The heat of it bakes the rocks that are in contact with it. The hot liquids and gases can enter into the rock and react with the minerals therein.

Review!! Igneous comes from _________? Sedimentary comes from _______? Metamorphic comes from ________? Each of these are related to each other, and they come together to form the ROCK CYCLE!

Rock Cycle Lab You will now create your own rock cycle, and write down how each cycle is related to the other using this handout. Can I get a volunteer to pass out the handouts please? Please listen carefully to the instructions, and I will also put them up on the screen for you to read. Please maintain a clean environment to work with. If you leave a mess, I will hold you after class to help clean up. You will not receive an excused tardy! Be careful, boiling water will be used, so please do not bump, push or horseplay around it. I want NO BURNS!

1.Place your newspaper on the desk in front of you. This is your work mat to help you keep things clean! 2.I want you or your partner to come up and take one sheet of aluminum foil, and 2 to 3 crayons, and ONE plastic knife per group. 1. This knife is not a weapon or a toy. Anybody caught horse-playing with it will be given a zero and will be kept after class 3.Peel the crayons. Place them on your foil and look up when you are finished.

4. What type of rock does this crayon resemble? (Think about the size of the crystals. Can you see them? Are they grainy, smooth, glossy?) 5. Choose one of your crayons and scrape a moderate pile onto your foil. This will be your parent rock. (You do not need to scrape the entire crayon out of existence) 6. Now make a secondary pile off of the foil. This pile should be smaller. What do these two piles represent? From what type of rocks could these have come from? 7.Mix them together on the center of your foil, and fold the foil together. Apply pressure and flatten the crayon shavings. 8.Open the foil – describe what you see. What type of rock does this represent?

Make a boat out of your foil now, with your sedimentary rock in the center. Make sure no water can leak into it. When you are ready, bring your boat up front, and dip the bottom of it into the hot water. Allow the crayons to melt together, and take them out before the colors blend together completely. What type of rock does this represent?

Ticket out the Door We covered the rock types, and the rock cycle. Can you tell me the differences between igneous, sedimentary, and metamorphic rock? Can you relate them together in the rock cycle? Ticket out the door: Relate plate tectonics to the rock cycle on a half sheet of paper with your name on it.