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Mrs. Griffin.  Granite, very durable.  Rhodes Memorial in Cape Town, South Africa…..De Beers?  Cecil Rhodes  Vietnam Memorial.

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Presentation on theme: "Mrs. Griffin.  Granite, very durable.  Rhodes Memorial in Cape Town, South Africa…..De Beers?  Cecil Rhodes  Vietnam Memorial."— Presentation transcript:

1 Mrs. Griffin

2  Granite, very durable.  Rhodes Memorial in Cape Town, South Africa…..De Beers?  Cecil Rhodes  Vietnam Memorial

3  Igneous rocks are formed from the crystallization of magma.  Lava is magma that flows out onto Earth’s surface.

4  Extrusive- fine- grained, that cool on Earth’s surface.  Intrusive-coarse- grained, that cool slowly beneath Earth’s surface.  Granite

5  Slushy mix of molten rock, gases, and mineral crystals.  Elements are the same as the major elements found in Earth’s crust: O, Si, Al, Fe, Mg, Ca, K, Na.  Silica (SiO2) is the most abundant compound found in magma. Magmas are classified as basaltic, andesitic, and rhyolitic based on the amount of silica they contain:  Basaltic 50%, andesitic 60%, rhyolitic 70%

6  Temperature, pressure, water content, and mineral composition.  Temperature and pressure/Earth’s crust: increase or decrease?  Water-> changes the melting point of rocks; as water content increases, the melting point decreases.  Different minerals have different melting points.

7  Water, candle wax, and ice tray.  Rocks contain different minerals and therefore have different melting points….this is why magma is often slushy.  Partial melting: where some minerals melt at low temperatures while others remain solid.  Fractional crystallization: the process where different minerals form at different temperatures.  The 1 st minerals to crystallize from magma are the last minerals to melt during partial melting.

8  Further classify by mineral composition: 3 main groups of igneous rocks:  Felsic- granite, light-colored, & have high silica content, and contain quartz and the feldspars orthoclase and plagioclase.  Mafic rocks-include gabbro, dark colored, lower silica contents, rich in iron and magnesium.  Ultramafic- peridotite and dunite, have low silica content and high levels of iron and magnesium.  Diamonds are found in ultramafic rocks known as kimberlites. ▪ Kimberly Diamond Mine in South Africa

9  Grain size- obsidian no visible mineral grains vs. gabbro.  Texture, such as glassy.  Porphyritic texture- characterized by large, well- formed crystals surrounded by finer grained crystals of the same mineral or different minerals.

10  What are igneous rocks? How are they formed?  Compare and contrast intrusive/extrusive rocks?  What is partial melting?  Explain fractional crystallization.

11 Mrs. Griffin

12  Much of Earth’s surface is covered with sediments- pieces of solid material that have been deposited on Earth’s surface by wind, water, ice, gravity, or chemical precipitation.  Up or down?  When these sediments become cemented together they form sedimentary rocks. This process begins when weathering and erosion produce sediments.

13  A set of physical and chemical processes that break rock into smaller pieces.  Produces rock and mineral fragments known as clastic sediments. How is a solid rock formed from clastic sediments?  Weathering  Erosion and transport  Deposition  Burial and lithification

14  The primary feature of sedimentary rocks is bedding.  Graded bedding- particle sizes become progressively heavier and coarser towards the bottom layer.  Cross bedding- inclined layers of sediment move forward across a horizontal surface.

15  The best-known features of sedimentary rocks is what???  Fossils

16  The most common type of sedimentary rocks are clastic rocks. These can be further classified according to the sizes of their particles.  Coarse-grained- breccia  Medium-grained- sandstone, an important feature: porosity, the % of open spaces b/w grains in a rock.  Fine-grained- siltstone.

17  When rocks are buried at great depths, pressure and temperature increase -> rocks melt and form magma.  What happens if they don’t get to this point? ▪ Rock will change form while remaining solid, metamorphism.  When high temperature and pressure affect large region’s of the Earth’s crust they produce large belts of regional metamorphism.

18  Classified into two textural groups:  Foliated- wavy layer and bands of minerals, schist and gneiss.  Nonfoliated- lack mineral grains with long axes in one direction, quartzite and marble.

19  The continues changing and remaking of rocks.

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