Hafeet mountain Rocks
There are several steps that lead to form the rocks Weathering Erosion Deposition Heat and pressure
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)
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
Deposition Its a process that lead to laying down the eroded sediments The major factor that control on this process is GRAVITY
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
Rock cycle
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.
Igneous rock Jees mountain - UAE
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 )
Now lets talk about the igneous rock classification Igneous rock classification Classified by composition classified by the size of grains Felsic Mafic Intrusive (coarse grains ) Extrusive (fine grains ) Granite Gabro Granite & Gabro Rhyolite & Basalt
Igneous bodies
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.
Where can l fine an extrusive igneous rock? 1. From volcanoes 2. From mid ocean ridges
Sedimentary rocks
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.
Follow the below chart that lead to form the sedimentary rocks Weathering A process in which sediments formed. Erosion Transferring the sediments. Deposition Laying down of the sediments 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 )
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
Sedimentary rock classification Clastic (according to the size of grains ) Non- clastic Fine (shale) Medium(silt &sand stone) Coarse (conglomerat e) Chemical(hali te) Organic(fossil iferous lime stone )
Clastic sedimentary rocks
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.
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.
Halite
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.
Example of organic sedimentary rock
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
Ripple marks
Mud cracks
Metamorphic rocks
The meaning of metamorphic rocks They are rocks their own composition and texture has been changed because of intense heat and pressure.
What are types of metamorphisim? Metamorphism Contact Regional Controlled by heat Controlled by pressure Happen because immediatlly magma intrusion Happen at the plate boundaries espicially in the convergent boundaries
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
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.
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
What is Garnet Its one of the index minerals which shows the highest amount of metamorphism.
Classification of metamorphic rocks. Metamorphic rocks Foliated Non-foliated The texture of metamorphic rock in which the mineral grains are arranged in planes or bands The texture of metamorphic rock in which the mineral grains are not arranged in planes or bands
Example of foliated metamorphic Foliated metamorphic rock usually contains aligned grains of flat minerals, such as biotite mica or chlorite rocks
Example of non-foliated rocks
Done by Mr,Ali Science teacher