Journal Entry • Open books to P. 116-117 to analyze picture and answer questions • What is distinctive about this rock formation? • What does the shape of this rock formation suggest about how it was formed. ( How do you think it was formed? • Where do you think this is?
Rocks • What is a rock? • Rocks and Minerals are often confused. It is important to understand the difference. • A rock is: ________________________
3 types • Igneous- from cooling magma inside earth or cooling lava on surface of earth • Sedimentary- made of broken up bits of rocks (called sediment) which is eventually cemented together • Metamorphic- deformed rock
Rock cycle • Shows the interrelationships among the three rock types • Earth as a system: the rock cycle • Magma • Crystallization • Igneous rock • Weathering, transportation, and deposition
Rock cycle • Earth as a system: the rock cycle • Full cycle does not always take place due to "shortcuts" or interruptions • e.g., Sedimentary rock melts • e.g., Igneous rock is metamorphosed • e.g., Sedimentary rock is weathered • e.g., Metamorphic rock weathers
Rock cycle • Earth as a system: the rock cycle • Sediment • Lithification • Sedimentary rock • Metamorphism • Metamorphic rock • Melting • Magma
Magma • Crystallization- What is it? • Cooling magma creates Igneous rocks
Check up Quiz • Can an igneous rock become another igneous rock? • How are the processes involved with the formation of Igneous and metamorphic rocks different? • Is there a beginning or end to this cycle?
Igneous Rock Igneous rock exposed at earth’s surface is weathered, transported and deposited at a new location as sediment
Sediment Lithification • Sediment- What is it? • Lithification- Sediment hardening creates Sedimentary rocks.
Sedimentary Rock • As Sediment continues to be deposited and as layers become thicker the rock becomes deformed • Metamorphism- Solid state changes in sedimentary or igneous rocks. • Metamorphism of rock creates new class of rock called….
Metamorphic Rock • As pressure and temperature increase, for various reasons (Subduction, Volcanism, Lithification), a rock may begin to melt • Recreates Magma
Magma • Melting occurs and the whole process starts over.
Link: **Rock Cycle Movie- (5 mins)** **Rock Cycle Animation**
Igneous rocks • Form as magma cools and crystallizes • Rocks formed inside Earth are called plutonic or intrusive rocks • Rocks formed on the surface • Formed from lava (a material similar to magma, but without gas • Called volcanic or extrusive rocks
Igneous rocks • Crystallization of magma • Ions are arranged into orderly patterns • Crystal size is determined by the rate of cooling • Slow rate forms large crystals • Fast rate forms microscopic crystals • Very fast rate forms glass
Link: • Rock Formation animation • Crystal Growth
Igneous rocks • Classification is based on the rock's texture and mineral constituents • Texture • Size and arrangement of crystals • Types • Fine-grained – fast rate of cooling • Coarse-grained – slow rate of cooling • Porphyritic (two crystal sizes) – two rates of cooling • Glassy – very fast rate of cooling
Igneous rocks • Classification is based on the rock's texture and mineral constituents • Mineral composition • Explained by Bowen's reaction series which shows the order of mineral crystallization • Influenced by crystal settling in the magma
Igneous rocks • Naming igneous rocks • Granitic rocks • Composed almost entirely of light-colored silicates - quartz and feldspar • Also referred to as felsic: feldspar and silica (quartz) • High silica content (about 70 percent) • Common rock is granite
Igneous rocks • Naming igneous rocks • Basaltic rocks • Contain substantial dark silicate minerals and calcium-rich plagioclase feldspar • Also referred to as mafic: magnesium and ferrum (iron) • Common rock is basalt
Igneous rocks • Naming igneous rocks • Other compositional groups • Andesitic (or intermediate) • Ultramafic
Rock Quiz • Explain the Rock Cycle in your own words. Feel free to use an illustration • What are PIN’s? List 2 characteristics • What are VEX’s? List 2 characteristics • Explain how rocks get their textures.
Sedimentary rocks • Form from sediment (weathered products) • About 75% of all rock outcrops on the continents • Used to reconstruct much of Earth's history • Clues to past environments • Provide information about sediment transport • Rocks often contain fossils
Sedimentary rocks • Sedimentary rocks are produced through lithification • Loose sediments are transformed into solid rock • Lithification processes • Compaction • Cementation by • Calcite • Silica • Iron Oxide
Sedimentary rocks • Features of sedimentary rocks • Strata, or beds (most characteristic) • Bedding planes separate strata • Fossils • Traces or remains of prehistoric life • Are the most important inclusions • Help determine past environments • Used as time indicators • Used for matching rocks from different places
Sedimentary rocks • Economic importance • Coal • Petroleum and natural gas • Sources of iron and aluminum
Sedimentary rocks • Classifying sedimentary rocks • Three groups based on the source of the material • Detrital rocks (CLASTIC) • Chemical • Organic
Detrital/Clastic Sed. Rocks • Material is solid particles • Classified by particle size • Boulder, Gravel, Pebbles, Sand, Clay…. • Common rocks include • Shale (most abundant) • Sandstone • Conglomerate
Chemical Sedimentary rocks • Many of these form when standing water evaporates, leaving dissolved minerals behind. • Unlike most other sedimentary rocks, chemical rocks are not made of pieces of sediment. Instead, they have mineral crystals made from elements that are dissolved in water.
Chemical Sedimentary rocks • Chemical rocks • Common sedimentary rocks • Limestone – the most abundant chemical rock • Microcrystalline quartz (precipitated quartz) known as chert, flint, jasper, or agate • Evaporitessuch as rock salt or gypsum • Coal
Formation • 1) Water becomes supersaturated • 2) Water dissolves which leaves less room for dissolved minerals • 3) Crystals begin to form, like halite- • Example: Salt Lake, UT • 4) Large crystal deposits