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Rock types.

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Introduction

ROCK types * There are 3 types of rocks. *Igneous *Sedimentary *Metamorphic Igneous * Formed when molten magma from mantle is pushed out through the earth's crust often through volcanoes forming hard and layered rocks with speckled appearance. These contains minerals randomly arranged in large and interlocking crystals as magma cools slowly inside the earth's crust. The cooling produces rocks that always contain crystals. * 2 types: intrusive and extrusive rocks *Intrusive rocks formed when molten magma from mantle cools slowly (underground) inside the earth's crust forming rocks with large crystals such as that of granite's. Granite is a very hard and decorative stone ideal for steps and buildings. *Extrusive rocks formed when molten magma from mantle cools quickly above the earth's crust forming rocks with small crystals usually dark in colour such as that of basalt's. Sedimentary * formed from layers of sediments laid deep down inside lakes or seas over millions of years. The layers are cemented together by salt crystals. * Made up from fragments of older rocks that have been weathered or may have formed from the remains of living organisms. * Formed in layers and these may give additional evidence about the conditions they were formed and may show evidence on the wave ripples on their surface. S. Rocks with large and coarse-grained particles were probably deposited under active conditions, such as on a stormy beach S. ...read more.

Middle

B. Slate [squashed mudstone] - as mudstone is heated and compressed a lot, its tiny particles align in the same direction which allows slate to be split into thin sheets in that direction making it an ideal roofing material. C. Schist [heated mudstone]- as mudstone is heated a lot and compressed, new minerals like mica start to form the rock schist containing a band of interlocking crystals. ROCK cycle - takes millions of years to complete! * The amount of rock on earth is always about the same, even though it is weathered away. * Involves changing the 3 types of rock - IGNEOUS, SEDIMENTARY and METAMORPHIC from one form to another. * This happens by the following processes: 1. WEATHERING: the breakdown of rocks 2. TRANSPORATION: movement of the eroded rock bits round the world by wing and water. 3. DEPOSITION: sediment being laid down. 4. BURIAL / COMPRESSION: squeezing and compressing the layers - which eventually form sedimentary rocks. 5. HEAT/PRESSURE: the rocks being further heated and squashed which turns rocks into metamorphic rocks. 6. MELTING: by intense heating, the rock completely melts that forms igneous rocks. 7. COOLING: the molten rock solidifying. Geological Changes * This involves changes to rocks both inside and outside the Earth's crust. What is WEATHERING? * Breakdown of rocks into smaller bits. * There are 3 types of Weathering. ...read more.

Conclusion

and sodium carbonate to make (soda glass) used in windows. * Heated with sand (silicon oxide), sodium carbonate and boron oxide to make borosilicate glass such as Pyrex which are harder then soda glass. * Mixed with iron ore and coke to form the charge which is loaded into a blast furnace. The limestone reacts with the high melting point non-metal impurities in the iron ore to form a molten slag which floats on top of the iron. * Mining and Quarrying which creates visual pollution as ugly slag heaps are created which scar the landscape. They cause dust and smoke pollution and generate a lot of heavy traffic because of the transportation of rocks. Cement * Produced by roasting powered limestone with powdered clay in a rotary furnace. * When cement is mixed with water, sand and crushed rock, a slow chemical reaction produces a hard, stone-like building material called concrete. Cement + water + sand + crushed rock � concentre (stone like building material) Glass * Made by heating a mixture of limestone, sand and sodium carbonate (soda). * Used in industry to make bottles, containers etc. Erosion * The wearing away of exposed rocks. Transport * The process of carrying away the rock fragments, either falling away due to gravity or being carried away by rivers. * The rocks travelling down rivers get worn down as they go and they also wear away the river bed causing river valleys. The Grand Canyon is a grand example. ...read more.

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