BELLRINGER QUESTION:

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Adelia Owens
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2 BELLRINGER QUESTION: Why are rocks important to us? Are all rocks made of minerals? Buildings, Roads, Bridges, Concrete, Extract minerals like iron (Fe) to make steel, Toothpaste, Salt, Sandpaper, Decorations, Jewelry Yes

3 Minerals vs. Rocks Minerals Similarities Rocks Inorganic Made of elements Can be organic Naturally occurring Solid structure Can be man made Made of element compounds Have crystals Made of mixture of minerals Can be formed from solutions Can be made of lava/magma

4 Types of Rock Rock natural material that makes up the solid parts of Earth, made of one or more minerals Based on the processes that form and change the rocks of Earth s crust, geologists classify rocks into three major types by the way the rocks form. Igneous rock Sedimentary rock Metamorphic rock

5 Magma Formation Magma forms when rock melts Rock will Melt : 1.) When rock is heated must reach above melting point of minerals Minerals melting point (temperature) is determined by its chemical composition 2.) When pressure changes A decrease in pressure lowers the melting temperatures of materials Occurs at mid-ocean ridges An increase in pressure causes materials to melt at hot spots 3.) Water presence Water lowers the melting point of materials

6 Properties of Rocks All rock has physical and chemical properties that are determined by how and where the rock is formed The physical characteristics reflect the chemical composition of the rock and the minerals that make up the rock Rate of rock weathering and breakage is determined by chemical stability of the minerals

7 Bowen s reaction series Bowen s Reaction - minerals crystallize from cooling magma according to their chemical composition and melting point Fractional crystallization: different minerals form at different times, changing the composition of the cooling magma first crystals to melt in partial melting will be the first minerals to crystallize out when the magma begins to cool. Therefore, mafic minerals will crystallize first, followed by felsic minerals.

9 Partial Melting Partial melting occurs when only a portion of a solid rock is melted. A rock containing several different minerals will go through partial melting minerals with lowest melting points will melt first changing the chemical composition of the original rock.

10 Fractional Crystallization When magma cools, the cooling process is the reverse of the process of partial melting. Process is reverse of partial melting process Minerals with higher freezing points crystallize first, removing chemicals from the magma Crystals that form early are largest longest time to grow Chemical composition of inner crystal differs from composition of outer parts Due to magma s composition change while crystal grows

11 Fractional Crystallization

12 Study the two image progressions and summarize what is happening in the fractional crystallization and partial melting. Both processes are related to magma. Tell your summary to your diving buddy.

13 Rock Cycle Objectives Summarize the steps of the rock cycle Describe what provides the energy for the rock cycle Rock Cycle Song

14 Why is it important to have a basic understanding of the rock cycle? Rocks contain clues about the environment. Helps us understand the formation of the earth.

15 What is the law of conservation of matter? Law of conservation of matter states that matter cannot be created or destroyed. The changes that take place in the rock cycle never destroy or create matter. The elements are just redistributed in other forms.

16 What is the rock cycle? To show how rocks slowly change through time, scientists have created a model called the rock cycle. It illustrates the processes that create and change rocks.

17 Rock Cycle Any type of rock (igneous, metamorphic, sedimentary) can be changed into another of the three types. rock cycle the series of processes in which rock forms, changes from one form to another, breaks down, and forms again by geological processes Geologic forces and processes cause rock to change from one type to another.

18 What causes the rock cycle? Energy Processes driven by heat from Earth's interior are responsible for forming both igneous and metamorphic rocks. Interior heat of the Earth powers the rock cycle through a process called convection

19 Convection Convection the movement of matter due to differences in density that are caused by temperature variation; can result in the transfer of energy as heat

20 What causes the rock cycle? The energy from the sun Weathering and the movement of weathered materials are external processes powered by energy from the sun.

21 Weathering forms Sediment

22 Steps of the Rock Cycle Step 1 Rock melts forming magma due to burial Burial is when rock gets pushed deep into Earth s crust

$create rock as magma cools (fractional crystallization) Magma cools because of uplift Uplift is when rock is forced toward Earth s$

23 Step 2 Magma cools off forming igneous rock -involves crystallization and solidification Crystallization formation of minerals that create rock as magma cools (fractional crystallization) Magma cools because of uplift Uplift is when rock is forced toward Earth s surface

24 Forms Sediment Step 3 Igneous rock is exposed to weathering creating sediment

25 Weather vs. Erosion Weathering and Erosion When rock is exposed to air, water, or ice, it breaks down chemically and physical (mechanical) into small pieces. Physical involves water, wind, and temperature acting directly on the rock to break it down Chemical involves acid rain and rust, due to reaction between molecules in atmosphere. This process, which breaks rocks into smaller pieces, is called weathering. The movement of weathered material is called erosion.

26 Step 4 Sediment is transported by erosion Sediment is transported to a new location by wind, gravity, water, ice Types of sediment includes: gravel, sand, silt, mud, clay, soil

27 Step 5 Sediment is deposited (deposition) the laying down of sediment carried by wind, water, or ice

28 Step 6 Sediment goes through compaction and cementation Compaction sediment squeezed together Cementation sediment is glued together from mineral precipitates Lithification is a term that refers to both compaction and cementation as one process

29 Step 7 Sedimentary rock forms

30 Step 8 Sedimentary rock goes through burial and then is exposed to extreme heat and/or pressure that leads to metamorphism

31 Step 9 Metamorphic rock forms

32 It s a Cycle! Sedimentary and metamorphic rock can weather and erode to become sediment Igneous and sedimentary rock can melt and form magma Igneous rock can undergo heat and pressure to become metamorphic rock

33 Igneous Rock Objectives Describe how igneous rock forms Determine the ways igneous rock is classified Identify the families of igneous rock

34 Igneous rock Igneous: forms when magma, or molten rock, cools and hardens. Igneous rocks are classified by: Where they were formed Texture/What they are made from (mineral composition)

35 1.)Where they Form Igneous rocks are classified according to where magma or lava cools and hardens (solidifies). 1. Intrusive igneous rock cooling and solidification of magma Beneath earth s surface 2. Extrusive igneous rock cooling and solidification of lava at earth s surface

36 Intrusive Igneous Rocks Intrusive igneous rocks can also be called plutonic. The word plutonic comes from Pluto, the name for the Greek god of the underworld. They form when magma enters a pocket or chamber underground that is relatively cool and solidifies into crystals it cools very slowly.

37 Rock Structures Intrusive Igneous Rock Structures: Intrusions: when magma enters other rock masses underground Batholiths, Laccoliths, Sills-magma, Dikes

38 Extrusive Igneous Rocks Also called volcanics form when magma makes its way to Earth's surface. The molten rock erupts or flows above the surface as lava, and then cools quickly forming rock. Are exposed to weathering and erosion Examples include basalt, rhyolite, and andesite.

39 Rock Structures Extrusive Igneous Rock Structures: Extrusions- igneous rock masses that form on Earth s surface Volcanoes, Volcanic necks, Lava flows, Lava plateaus, Tuffs

40 2.)Texture/ What they are made of The texture of igneous rock is determined by the size of the mineral crystals in the rock. The size of the crystals is determined by the cooling rate of the magma. Rocks can have a mixture of large and small mineral crystals called a porphyritic texture.

41 Igneous Texture Categories A. Coarse-Grained Igneous Rock Intrusive igneous rocks cool slowly, they commonly have large mineral crystals. Igneous rocks that are composed of large, welldeveloped mineral grains are described as having a coarse-grained texture. B. Fine-Grained Igneous Rock Extrusive igneous rocks cool rapidly, they are commonly composed of small mineral grains. Igneous rocks that are composed of small crystals are described as having a fine-grained texture.

Intrusive Igneous Rock Rock have large, well

Earth, the larger the igneous rocks crystals

42 Intrusive Igneous Rock Rock have large, well formed crystals, large enough to see without a microscope. The more slowly molten rock cools within the Earth, the larger the igneous rocks crystals will be. Examples of intrusive igneous rocks are granite, gabbro and diorite Granite Gabbro Diorite

Glassy Igneous Rocks or Volcanic Glass Glassy Igneous Rocks

Has small amount of gasses Pumice (left) Scoria (bottom left)

43 Glassy Igneous Rocks or Volcanic Glass Glassy Igneous Rocks cool so rapidly, that atoms don t have enough time to get together, bond and form crystals. To cool this quickly the rocks MUST be extrusive. Has small amount of gasses Pumice (left) Scoria (bottom left) Obsidian (bottom) Note gasses in the lava can cause fine holes called vesicles as seen in the pumice and scoria.

44 Rock Families What minerals are in rock is determined by chemical composition of the magma from which the rock forms 3 Families Felsic Mafic Intermediate

45 2b.) Igneous Rock Composition Families 1.) Felsic rich in feldspars and silica light in color Examples: granite, rhyolite, obsidian, pumice 2.) Mafic rich in magnesium and iron dark in color Examples: basalt and gabbro

46 Stop and Think Applying Ideas An unidentified, lightcolored igneous rock is made up of potassium feldspar and quartz. To what family of igneous rocks does the rock belong? Explain your answer.

47 Sedimentary Rock Objectives Describe how sedimentary rock forms Define sediment Understand how sedimentary rock provides clues about past history or Earth s environment and life forms

48 Garden of the Gods, Colorado

49 Sedimentary Rock About 70-75% of all the rocks on Earth are sedimentary rocks Found at top 10miles of Earth s crust The composition of a sedimentary rock depends upon the composition of the sediments from which it formed.

50 What is sediment? Sediments are loose materials such as rock fragments, minerals, and organic material that results from natural processes including the physical breakdown of rocks that have been moved by wind, water, ice, or gravity. Sediments come from already-existing rocks that are weathered and eroded. Sedimentary rock forms when sediments are pressed (compaction) and cemented together (when minerals form from solutions)

51 Stratification or Bedding Sedimentary rocks often form as layers of stacked rocks(stratification). Stratified layers, or beds, vary in thickness and composition. The older layers are on the bottom because they were deposited first. Sometimes, forces within Earth overturn layers of rock, and the oldest are no longer on the bottom.

52 GRADED BEDDING Fine gravelly lithounit Medium-coarse sandy lithounit (cross stratified)

53 Laminated layers of fine silt and clay Cross-stratified sst. Paleo-flow from right to left

54 Sedimentary Rock Formation Sedimentary formation: form when rocks, mineral crystals, and organic matter have been broken into fragments, called sediments, and are compressed and cemented together. Sediment forms from weathering Sediment is transported by wind, water, ice, or gravity to new location Sediment is deposited Sediment is compacted Sediment is cemented Compaction and cementation together can be called Lithification

56 Formation Processes Compaction: volume (space) and porosity of a sediment is decreased by the weight of overlying sediments The bottom sediment layers are undergoing burial Cementation: minerals precipitate from water filling pore spaces between sediment grains and bind (cement) the sediment into rock

57 Classification 1. process of formation 2. composition of the rocks three types of sedimentary rocks chemical, organic, and clastic (dentritis) classes subclassify based on the shape, size, and composition of the sediments that form the rocks

58 1.Chemical sedimentary Rock Made from dissolved minerals in the water that formed into crystals (minerals precipitate from a solution or settle out of water) When water evaporates, the minerals that were dissolved in the water are left behind. Rocks that form through evaporation are called evaporites Gypsum and halite.

59 2.Organic Sedimentary Rock Rock that forms from the remains of plants or animals Coal and some limestones are examples of organic rocks. Organic limestones form when marine organisms, such as coral, clams, oysters, and plankton, remove the chemical components of the minerals calcite and aragonite from sea water. The organisms make their shells from these minerals, and when the organisms die, their shells settle to the bottom of the ocean, accumulate, and are compacted to form limestone.

60 Formation of Limestone- an organic sedimentary rock

61 3.Clastic Sedimentary Rock Rock that forms when fragments of preexisting rocks are compacted or cemented together Clastic sedimentary rocks are classified by the size and shape of the sediments they contain. A. Conglomerate: contains large, rounded pieces B. Breccia: contains large, angular pieces C. Sandstone: composed of sand-sized grains D. Shale: composed of clay-sized particles

62 Clastic Sediment Characteristics Physical characteristics of sediments are determined by the way sediments were transported before deposited. Both distance moved and method of movement determines the characteristics of sediment Sediments are transported by four main agents: water, ice, wind, and the effects of gravity. Erosion moves sediment particles and alters the sediment shape

63 Sorting Sediment When currents of air or water separate sediments according to size it s called sorting. If well-sorted, all of the grains are roughly the same size and shape If poorly sorted consists of many different sized grains The sorting of a sediment is the result of changes in the speed of the air or water that is moving the sediment. Faster-moving currents can carry larger particles than slower-moving currents can.

64 Angularity of Sediment Degree of roundness helps in knowing the distance of transportation (method of erosion) Angular clasts- short distance transport from the sourc Rounded clasts- long distance transport

65 Providing Environmental Clues Grain Size - Power of Transport Medium Grading - Often Due to Floods Rounding Sorting Cross-bedding - Wind, Wave or Current Action Ripple marks Mud cracks Color And Chemistry Red Beds - Often Terrestrial Black Shale - Oxygen Poor, Often Deep Water Evaporites Arid Climates

66 Ripple marks

67 Mud cracks Biogenic structures Foot prints

68 Contain Fossils Fossils are the remains of organisms that are preserved in rock. As sediments pile up remains are buried Hard parts of remains may be preserved Even hard parts can dissolve, but impression is left behind Fossils Salt Water - Corals, Echinoderms Fresh Water - Insects, Amphibians Terrestrial - Leaves, Land Animals

69 Metamorphic Rock Objectives Describe the process of metamorphism. Explain the difference between regional and contact metamorphism. Distinguish between foliated and nonfoliated metamorphic rocks, and give an example of each.

What is a metamorphic rock? The term "metamorphic" means "to change form." Any rock (igneous, sedimentary, or metamorphic) can become a metamorphic rock.

70 What is a metamorphic rock? The term "metamorphic" means "to change form." Any rock (igneous, sedimentary, or metamorphic) can become a metamorphic rock. If rocks are buried deep in the Earth at high temperatures and pressures, they form new minerals and textures all without melting. If melting occurs, magma is formed, starting the rock cycle all over again.

71 Metamorphic Rock Metamorphic rock: forms when existing rock is altered by changes in temperature, pressure, or chemical processes. Metamorphism: process by which heat, pressure, or chemical processes change rock Usually forms deep within Earth s crust

72 During Metamorphism heat, pressure, and hot fluids cause some minerals to change into other minerals. Minerals may also change in size or shape, or they may separate into parallel bands that give the rock a layered appearance.

73 Indicators of Condition The type of rock that forms because of metamorphism can indicate the conditions under which the original rock changed. Conditions that Indicators suggest: The composition of the rock being metamorphosed the amount and direction of pressure presence or absence of certain fluids

74 2 Types of Metamorphism 1.contact metamorphism -a change in the texture, structure, or chemical composition of a rock due to contact with magma or something hot 2.regional metamorphism a change in the texture, structure, or chemical composition of a rock due mainly to pressure over a large area generally are a result of tectonic forces The rocks are squished Most metamorphic rocks form this way

75 Classification Primarily classified by texture Foliated rock Nonfoliated rock Chemical composition also helps classify

77 The end!

alreadyexisting rocks that are weathered and eroded forms when sediments are pressed and cemented together, or when minerals form from solutions Detrital Chemical Organic

78 alreadyexisting rocks that are weathered and eroded forms when sediments are pressed and cemented together, or when minerals form from solutions Detrital Chemical Organic compactio n Broken fragments of other rocks Dissolved minerals come out of solution Made of the remains of once living things cementatio n weathering limeston e Halite chalk coal erosion

79 To change form Other rocks are exposed to high heat & pressure Foliated Non-Foliated Flattened & pushed into parallel layers layers Quartzite Anthracit e coal slate gneiss marble shale

80 Lava Slowly Crystal size granitic High SiO 2 Low Fe & Mg Light colored, less dense Small or not visible Physical & chemical properties On the continents Pumice, obsidian, basalt magm a slowly large Granite, gabbro, diorite Extrusive Intrusiv e when molten rock cools and solidifies Magma (below) Lava (above) andesiti c basaltic b/t basaltic & granitic Grey, medium Pacific Rim Rich in Fe & Mg poor in SiO 2 Dense & dark colored Ocean floor & Hawaii

Chapter 10. Chapter Rocks and the Rock Cycle. Rocks. Section 1 Rocks and the Rock Cycle

Chapter 10. Chapter Rocks and the Rock Cycle. Rocks. Section 1 Rocks and the Rock Cycle Chapter 10 Rocks 1 Chapter 10 Section 1 Rocks and the Rock Cycle 2 10.1 Rocks and the Rock Cycle Magma is the parent material for all rocks. Once the magma cools and hardens, many changes can occur. Geology: