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Rocks Hafeet mountain
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There are several steps that lead to form the rocks
Weathering Erosion Deposition Heat and pressure
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Weathering Ice (expand inside the rock fractures)
Plants (grows through fractures ) Changing temperature Sea waves All of these factors lead to form sediments (small rock fragments)
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Erosion Since we got the sediments now its time to transfer them to a new place by a process called erosion Factors control on erosion : 1- water 2- wind
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Deposition Its a process that lead to laying down the eroded sediments
The major factor that control on this process is GRAVITY
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Heat and pressure All the sediments which they laid down they will expose a lot of heat and pressure in order to form the final rock after that the new rock will go in a process called ROCK CYCLE
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Rock cycle
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Rock cycle : its a continues process that led to form different types of rocks . Types of rocks : 1- sedimentary. 2- igneous. 3- metamorphic. The rocks has been classified according to their own texture and composition.
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Igneous rock Jees mountain -UAE
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First we have to know how lava formed
1- changing the composition of other rock. 2- applying pressure 3- finally the temperature But how all of these factors works in order to form the lava? . (Check up the next slide )
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Now lets talk about the igneous rock classification
Classified by composition Felsic Granite Mafic Gabro classified by the size of grains Intrusive (coarse grains ) Granite & Gabro Extrusive (fine grains ) Rhyolite & Basalt
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Igneous bodies
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When magma intrudes, or pushes, into surrounding rock below the Earth’s surface and cools, the rock that forms is called intrusive igneous rock.Intrusive igneous rock usually has a coarse-grained texture because it is well insulated by surrounding rock and cools very slowly. The minerals that form are large, visible crystals. Plutons: are large, irregular-shaped intrusive bodies. batholiths :The largest of all igneous intrusions. Stocks: are intrusive bodies that are exposed over smaller areas than batholiths. Dikes: Sheetlike intrusions that cut across previous rock units Sills : are sheetlike intrusions that are oriented parallel to previous rock units.
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Where can l fine an extrusive igneous rock ?
From volcanoes From mid ocean ridges
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Sedimentary rocks
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How sedimentary rocks formed?
Sedimentary rock forms at or near the Earth’s surface. It forms without the heat and pressure that are involved in the formation of igneous and metamorphic rocks.
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Follow the below chart that lead to form the sedimentary rocks
Compaction and cementation All the sediments start to compact to each other , after that some minerals work as glue that hold all the particles of the rock together by cementation process (quartz or calsite ) Deposition Laying down of the sediments Erosion Transferring the sediments. Weathering A process in which sediments formed.
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The most noticeable feature of sedimentary rock is its layers, or strata. A single, horizontal layer of rock is sometimes visible for many miles. Younger Older
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Sedimentary rock classification
Clastic (according to the size of grains ) Fine (shale) Medium(silt &sand stone) Coarse (conglomerate) Non- clastic Chemical(halite) Organic(fossiliferous lime stone )
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Clastic sedimentary rocks
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Is made of fragments of rocks cemented together by a mineral such as calcite or quartz
Cementation : is a process in which a clastic rock stick together They have coarse-grained, medium-grained, or fine-grained textures.
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Chemical sedimentary rock
Chemical sedimentary rock forms from solutions of dissolved minerals and water. Halite, one type of chemical sedimentary rock Halite forms when sodium ions and chlorine ions in shallow bodies of water become so concentrated that halite crystallizes from solution.
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Halite
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Organic sedimentary rock
This type of rocks form from animals remains . Most limestone forms from the remains, or fossils, of animals that once lived in the ocean These animal remains eventually become cemented together to form fossiliferous limestone.
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Example of organic sedimentary rock
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Sedimentary Rock Structures
Stratification : is the process in which sedimentary rocks are arranged in layers. Ripple marks : recording the motion of wind ,water waves and sand dunes in a sedimentary rock . Mud cracks: form when fine-grained sediments exposed to the air and dry out
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Ripple marks
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Mud cracks
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Metamorphic rocks
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The meaning of metamorphic rocks
They are rocks their own composition and texture has been changed because of intense heat and pressure.
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What are types of metamorphisim?
Metamorphism Contact Controlled by heat Happen because immediatlly magma intrusion Regional Controlled by pressure Happen at the plate boundaries espicially in the convergent boundaries
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Contact metamorphism The greatest change takes place where magma comes into direct contact with the surrounding rock. The effect of heat on rock gradually decreases as the rock’s distance from the magma increases and as temperature decreases. Contact metamorphism occurs near igneous intrusions
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Regional metamorphism
When pressure builds up in rock that is buried deep below other rock formations or when large pieces of the Earth’s crust collide with each other, regional metamorphism occurs. The increased pressure and temperature causes rock to become deformed and chemically changed.
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The composition of metamorphic rocks
Metamorphism occurs when temperature and pressure inside the Earth’s crust change. Minerals that were present in the rock when it formed may not be stable in the new temperature and pressure conditions. Index minerals can indicate the amount of heat , pressure and depth
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What is Garnet Its one of the index minerals which shows the highest amount of metamorphism.
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Classification of metamorphic rocks.
Foliated The texture of metamorphic rock in which the mineral grains are arranged in planes or bands Non-foliated The texture of metamorphic rock in which the mineral grains are not arranged in planes or bands
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Example of foliated metamorphic rocks
Foliated metamorphic rock usually contains aligned grains of flat minerals, such as biotite mica or chlorite
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Example of non-foliated rocks
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Done by Mr,Ali Science teacher
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