4Three Major Types of Rocks Igneous Rocks: “meaning from fire”Formed when magma cools and hardens.Magma is called lava when it reaches the earth’s surface.
5Three Major Types of Rocks Sedimentary Rock:All types of rock, minerals, and organic matter that have been broken into fragments by forces.Wind, water, iceDeposits harden after being compressed together.
6Three Major Types of Rocks Metamorphic Rock: “changed form”When an existing rock undergoes extreme forces it changes form.Tremendous pressureExtreme heatChemical processes
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8The Rock Cycle A cycle is a series of changes Geological forces and processes cause rock to change from one type to another and back again.Rocks in the crust have passes through the cycle many times.
1210.2 Igneous Rocks Objective Students will be able to identify different igneous rocks based on compositionStandard3c – explain the properties of rocks based on their chemical & physical composition
13Formation of Igneous Rock When lava cools and hardens it forms igneous rock.The rock has two categories and is based on how the lava cools.Intrusive igneous rockExtrusive igneous rock
14Intrusive Igneous The cooling of magma deep below the earth’s surface. Called intrusive because the lava that forms them intrudes other rocks.The magma then slowly cools to form rock.The slow cooling allows minerals to collect and form large crystals.
15Extrusive IgneousFormed when there is a rapid cooling of lava or melting of rocks on the earth’s surface.The rapid cooling does not give crystals time to form.The main difference between the two types of igneous rock is the size of the crystal when the rock is forming.
16Texture of the RocksThe larger the crystals, the more rough the rock will be.When rapid cooling occurs and crystal are not allowed the opportunity to form, the rock will appear extremely smooth.Crystal formation will be so small that they are not seen by the unaided eye.
17Texture of the RocksAn igneous rock with both large and small crystals is called porphyritic.The porphyritic texture is created when lava cools slowly and is then sped up.
18Texture of Rock When thick lava cools rapidly no crystals form at all. Usually thicker lava has an increased amount of trapped gases and this will cause the igneous rock to become full of holes.
19Composition of RockThe mineral make of the lava determines the chemical make-up of the rock.There are 3 different types of families:FelsicMaficIntermediate
2110.3 Sedimentary Rock Objective Students will be able to identify the 3 types of sedimentary rocks.Standard3c – explain the properties of rocks based on their chemical & physical composition
22Formation of Sedimentary Rock Made up of an accumulation of various types of sediment.Compaction or cementation are two process that form sedimentary rock.Compaction- when all air and water is squeezed out of sedimentCementation- when minerals are left between the fragments of sediment.
233 Types of Sedimentary Rocks Clastic Sedimentary Rock- rock is made up of rock fragments that have been moved by water, wind or ice.Chemical Sedimentary Rock- forms from minerals that precipitate from water.Organic Sedimentary Rock- forms from the remains of organisms.
24Clastic Sedimentary rocks Rocks are classified by the sediments size.Conglmerates- rocks composed of rounded gravel size fragments or pebbles.Individual pieces are easily seen.The sandstone group is made up of sand size grains that have been cemented together.The third group is shale, which consists of clay size particles the easily flake or break apart.
28Chemical Sedimentary Rocks Rocks that form from minerals that were once dissolved by water.These rocks are called evaporates.
29Organic Sedimentary Rock Formed out of the remains of living things.Coal is a prime example of this.
30Sedimentary Rock Features Easily identifiableLayeringRipples marksMudCracksFossilsConcretion
31Review Questions1. How does clastic sedimentation differ from chemical sedimentation?2. You expect a rock you found is sedimentary rock. What features would you be looking for to confirm you identification?
3410.4 Metamorphic Rock Objective Students will be able to explain how metamorphic rocks form.Standard3c – explain the properties of rocks based on their chemical & physical composition
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36FormationChanged from one type of rock into another by heat, pressure, and chemical processes.Form deep beneath the earth’s surface.ALL metamorphic rocks are formed from existing igneous, sediment or metamorphic rocks.
37FormationMinerals may change in size or shape or separate into parallel bands.Metamorphic formation happens two different waysContact metamorphismRegional metamorphism
38Contact Metamorphism Formed when magma pushes through existing rock. Changes the structure and mineral composition of surrounding rock.
39Regional Metamorphism Metamorphism sometimes occurs with tectonic plate movement.Tremendous heat and pressure is created at plates edge.This heat and pressure will cause chemical changes in the rocks.Most metamorphic rockis created be regionalmetamorphism.
40Classification of Rocks Rocks can be classified into two different types based on their texture:FoliatedNonfoliated