Rocks PPT

Chapter 3 Rocks Chapter 3 Rocks OBJECTIVES: IDENTIFY THE THREE TYPES OF ROCKS DISCUSS THE IMPORTANCE OF KNOWING THE TYPES AND PROCESS THROUGH WRITING. ILLUSTRATE THE PROCESS UNDERGONE BY ROCKS IN A CREATIVE WAY  What is Rock? Is an aggregate of one...

Chapter 3 Rocks Chapter 3 Rocks OBJECTIVES: IDENTIFY THE THREE TYPES OF ROCKS DISCUSS THE IMPORTANCE OF KNOWING THE TYPES AND PROCESS THROUGH WRITING. ILLUSTRATE THE PROCESS UNDERGONE BY ROCKS IN A CREATIVE WAY  What is Rock? Is an aggregate of one or more minerals w/c may or may not contain glass, organic matter and mineraloids. It undergoes transformation from one type to another 3 types of rocks  3 types of rocks There are 3 types of rocks found on Earth: – Igneous – Sedimentary – Metamorphic Knowing the differences between these 3 types of rocks allows us to learn about Earth’s past.  Igneous Rocks - Formation Igneous Rocks are formed by melting, cooling, and crystallization of other rocks. Igneous rocks form as a result of volcanic activity, hot spots, and melting that occurs in the  Formation of Igneous Rocks 1. Intrusive igneous rocks are formed when magma hardens beneath Earth’s surface. (plutonic rocks) 2. Extrusive igneous rocks are formed when lava hardens. (volcanic rocks)  Igneous Rocks – classification Crystal size is used to classify igneous rocks. Crystals form as the rock cools, and the crystal size can tell us a lot about its cooling history: – The larger the crystals, the slower it cooled. – The smaller the  Igneous Rocks - Classification Igneous rocks are classified using their texture in the following ways: – Glassy – Aphanitic – Phaneritic – Porphyritic  Igneous Rocks - Texture Glassy igneous rocks have no crystal structure, and probably formed by very rapid cooling (such as on the surface of a lava, or when a lava enters the water.)  Igneous Rocks - Texture Aphanitic or fine grained rocks have no visible crystals, and probably formed by fast cooling above ground. This are extrusive igneous rock Ex. Basalt and rhyolite  Igneous Rocks - Texture Phaneritic or coarse grained rocks have visible crystals, and probably formed by slow cooling below ground. Intrusive igneous rocks. Ex. Granite  Igneous Rocks - Texture Porphyritic rocks have both visible and nonvisible crystals, and probably formed by two different cooling events.  Igneous Rocks – Composition Classification Dark igneous rocks ⮚ Ultramafic igneous rocks contains ferromagnesian (45% silica content) ⮚ Mafic – igneous rock contains a lot of The magma that forms these rocks is magnesium and iron. usually very hot (around 1000°C) and viscous (about the same viscosity as (45-55% silica ketchup.) content)  Igneous Rocks – Composition Classification Light colored igneous rocks are formed from silicic (high silica content) ⮚ Intermediate characterized by minerals in transition from mafic to felsic (gray in color) (55% - 65% silica content) The magmas that form these rocks is ⮚ Felsic made up of usually more cool, (lower than 850°C), silicon potassium, and and more viscous (about the viscosity of peanut butter.) aluminum ( more than 65% silica content)  Igneous Rocks - Examples The most common types of igneous rocks include: – Rhyolite – Andesite – Basalt – Granite – Diorite – Gabbro Igneous rocks classification  Sedimentary Rocks - Formation Sedimentary rocks are formed by weathering, erosion, deposition, compaction, and cementation of other rocks. Sedimentary rocks form in areas where water, wind, or gravity  Sedimentary rocks - formation Sedimentary rocks are likely to form in areas such as: – Deltas – Beaches – Rivers – Glaciers – Sand dunes – Shallow seas – Deep oceans  Sedimentary Rocks Processes that rock convert into loose sediments Weathering Erosion  2.3 Sedimentary Rocks Weathering – when wind and water break rock down into smaller pieces, or sediment.  2.3 Sedimentary Rocks Erosion – the movement of sediments by wind, water, gravity, or other natural forces.  Sedimentary Rocks Sediments – loose fragments of rock, minerals and organic material that result from the breakdown of rock by weathering.  2.3 Sedimentary Rocks Deposition – the depositing and accumulation of sediment in an area.  2.3 Sedimentary Rocks Compaction – the process in which sediment is squeezed and the space in between grains is reduced by the weight of the overlying layers.  2.3 Sedimentary Rocks Cementation – the process in which sediments are glued together by minerals as water evaporates.  2.3 Sedimentary Rocks Types of sedimentary rocks are determined by processes in which the rocks form and their composition. Chemical Sedimentary Rock (CSR) Organic Sedimentary Rock (OSR) Clastic Sedimentary Rock (CSR)  2.3 Sedimentary Rocks Chemical Sedimentary Rock (CSR) – forms from minerals that were dissolved in water and as water evaporates minerals are left behind. rock salt, stalactites, and stalagmites  2.3 Sedimentary Rocks Organic Sedimentary Rock (OSR) – forms from the remains of living things. coal, chalk, and shell limestone Coquina, made with  2.3 Sedimentary Rocks Clastic Sedimentary Rock (CSR) – formed by rock fragments that are carried away from their source by water, wind, and ice and are compressed and glued together by minerals. Groups of CSR based on the size of the sediments Conglomerates: large grains Sandstones: sand sized grains Shales: fine grained Conglomerates Shales Sandstones  Sedimentary rocks - Examples Some of the most common types of sedimentary rocks include: – Conglomerate – Sandstone – Shale – Limestone – Gypsum – Oolites  2.4 Metamorphic Rocks Metamorphic Rock – rocks formed when existing rock is changed by heat and/or pressure. Metamorphism – the process in which heat, pressure, mechanical stresses and chemical processes change existing rock.  2.4 Metamorphic Rocks Types of Metamorphism Contact Metamorphism Regional Metamorphism  2.4 Metamorphic Rocks Contact Metamorphism – a change in the texture, structure, or chemical composition of a rock due to contact with magma. Only a small area of rock is changed by the heat. Often occurs near volcanoes.  2.4 Metamorphic Rocks Regional Metamorphism – a change in the texture, structure, or chemical composition or a rock due to changes in temperature and pressure over a large area. Large area of rock is changed. Result of tectonic movement.  Metamorphic rocks - Classification Metamorphic rocks are classified into 2 major groups: – Foliated – Nonfoliated  Metamorphic rocks - Classification Foliated rocks form when differential pressure causes minerals to form in layers. These rocks will have stripes or planes that they will break easily along. These “stripes” don’t usually line up with the original bedding  Metamorphic rocks Nonfoliated metamorphic rocks formed in areas where the pressure from all sides was equal, so there is no “linear” quality to the rocks.  Metamorphic rocks - Examples Some common types of metamorphic rock include: – Slate – Schist – Gneiss – Amphibolite – Marble – Quartzite  What is the importance of studying ROCKS? Studying rocks would be essential part in understanding the one of the earth system the geosphere. THANK YOU!