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The Rock Cycle. The Earth… It’s always changing…

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Presentation on theme: "The Rock Cycle. The Earth… It’s always changing…"— Presentation transcript:

1 The Rock Cycle

2 The Earth… It’s always changing…

3 All rocks that we have on earth today are made up of all the same stuff as the rocks that dinosaurs walked, crawled, or swam over. While the stuff that rocks are made of has stayed the same, the rocks themselves, have not. Over time rocks are recycled into new rocks QUESTIONS???  What are some modern uses of rocks?  How does a rock form? Every Rock Tells a Story….

4 When classifying a rock sample geologists observe the rock’s color and texture and determine its mineral composition. These observations help identify what type of rock it is. Texture: the size, shape, and pattern of the rock’s grain. Texture: the size, shape, and pattern of the rock’s grain. Color: the apparent color of the rock, on the inside and the outside. Color: the apparent color of the rock, on the inside and the outside. Mineral composition: The minerals that make up the different parts of a rock. Mineral composition: The minerals that make up the different parts of a rock.

5 The Rock Cycle

6 Another look at the Rock Cycle

7 What are the 3 major rock types and how can they change from one type to another type?

8 Rocks are classified by how they formed and what they’re made of. There are 3 general classes of rocks: Igneous RocksIgneous Rocks Metamorphic RocksMetamorphic Rocks Sedimentary RocksSedimentary Rocks

9 Igneous Rocks Igneous means “born of fire”

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11 Igneous Rocks Igneous Rocks… are formed when lava and magma crystallize to form solid rock. QUESTION???  How is lava different from magma?

12 Magma vs. Lava All igneous rocks differ from one another in what they are made of and how fast they cooled. All igneous rocks differ from one another in what they are made of and how fast they cooled. The longer it takes for the magma or lava to cool, the more time mineral crystals have to grow. The more time the crystals have to grow the coarser the texture of the resulting igneous rock. The longer it takes for the magma or lava to cool, the more time mineral crystals have to grow. The more time the crystals have to grow the coarser the texture of the resulting igneous rock. Magma is a hot liquid made of melted minerals. When magma pours onto the earth’s surface it is called lava. Magma is a hot liquid made of melted minerals. When magma pours onto the earth’s surface it is called lava. Igneous rock can form underground, where the magma cools slowly. Or, igneous rock can form above ground, where the magma cools quickly. Igneous rock can form underground, where the magma cools slowly. Or, igneous rock can form above ground, where the magma cools quickly. The crystals grow together and form one igneous rock. The crystals grow together and form one igneous rock.

13 Magma Bedrock

14 Three Dike Hill Big Bend National Park, Texas.

15 3 Ways a Rock Can Melt Temperature – An increase in temperature deep within the Earth’s crust can cause the minerals in a rock to melt. Pressure – The high pressure deep within the Earth forces minerals melt from intense heat and pressure. Composition – Fluids like water and carbon dioxide enter a rock that is close to its melting point. When these fluids combine with the rock, they can lower the melting point of the rock enough for it to melt and form magma.

16 INTRUSIVE IGNEOUS ROCKS – When igneous rocks are formed by magma that cools BENEATH Earth’s surface, they are called intrusive igneous rocks INTRUSIVE IGNEOUS ROCKS – When igneous rocks are formed by magma that cools BENEATH Earth’s surface, they are called intrusive igneous rocks EXTUSIVE IGNEOUS ROCKS – When igneous rocks are formed by LAVA ON Earth’s surface, they are called extrusive igneous rocks EXTUSIVE IGNEOUS ROCKS – When igneous rocks are formed by LAVA ON Earth’s surface, they are called extrusive igneous rocks 2 Types of Igneous Rocks

17 INTRUSIVE IGNEOUS ROCK Enchanted Rock, near Llano, TX is exposed intrusive formation made of granite.

18 EXTRUSIVE IGNEOUS ROCK Extrusive rock cools quickly on the surface and contains either very small crystals or none at all.

19 Example of Igneous Rock Lava flow Fort Davis State Park, Texas

20 Intrusive (has crystals) Extrusive (no crystals) Into the Bedrock On top (Exit)

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22 Sedimentary Rocks Sedimentary Rocks…are formed when sediments (sand clay, and silt) are compressed and become solid rock QUESTION???  Can you name the 4 ways Sedimentary Rock can be formed?

23 Formation of Sedimentary Rocks Erosion Erosion Deposition Deposition Compaction Compaction Cementation Cementation

24 Example of Sedimentary Rock Each layer takes approximately 10,000 years to make.

25 The process by which sediment becomes sedimentary rock 1 st step : Erosion 1 st step : Erosion 2 nd step : Deposition 2 nd step : Deposition 3 rd step : Compaction 3 rd step : Compaction 4 th step : Cementation 4 th step : Cementation Lithification Elephant Rock near Big Bend National Park, Texas

26 Sedimentary Rocks : Erosion Destructive forces are constantly breaking up and wearing away all the rocks on Earth’s surface The forces include heat and cold, rain, waves, and grinding ice Erosion occurs when running water or wind loosens and carry away the fragments of rock. Santa Elena Canyon Big Bend National Park

27 Santa Elena Canyon Big Bend National Park

28 Sedimentary Rocks: Deposition Deposition is the process by which sediment settles out of the water or wind carrying it. Deposition is the process by which sediment settles out of the water or wind carrying it. Moving water or wind slows and deposits the sediment. Moving water or wind slows and deposits the sediment. Sediment may include shells, bones, leaves, stems, and other remains of living things. Sediment may include shells, bones, leaves, stems, and other remains of living things. After sediment has been deposited, the processes of compaction and cementation change the sediment into sedimentary rock. After sediment has been deposited, the processes of compaction and cementation change the sediment into sedimentary rock. Remains of living things in the sediment may slowly harden and change into fossils trapped in the rock. Remains of living things in the sediment may slowly harden and change into fossils trapped in the rock. Overlook at La Cuesta Big Bend Ranch State Park

29 Alluvial Fan near Madera Canyon Big Bend Ranch State Park

30 Sedimentary Rocks: Compaction New sediments fit together loosely, but gradually, thick layers of sediment build up creating new layers. New sediments fit together loosely, but gradually, thick layers of sediment build up creating new layers. These layers are heavy and press down on the layers beneath them. These layers are heavy and press down on the layers beneath them. Compaction is the process that presses sediments together. Compaction is the process that presses sediments together. Weight of the layers compacts the sediments, squeezing them tightly together. Weight of the layers compacts the sediments, squeezing them tightly together. The layers often remain visible in the sedimentary rock. The layers often remain visible in the sedimentary rock. Rock Formation in Ernst Tinaja Canyon Big Bend National Park

31 Cementation is the process in which dissolved minerals crystallize and glue particles of sediment together. Cementation is the process in which dissolved minerals crystallize and glue particles of sediment together. While compaction is taking place, the minerals in the rock slowly dissolve in the water. While compaction is taking place, the minerals in the rock slowly dissolve in the water. The dissolved minerals seep into the spaces between particles of sediment. The dissolved minerals seep into the spaces between particles of sediment. It takes millions of years for compaction and cementation to transform loose sediments into solid sedimentary rock. It takes millions of years for compaction and cementation to transform loose sediments into solid sedimentary rock. Sedimentary Rocks: Cementation

32 Point A: Water or wind deposits sediments (Deposition) Point B: The heavy sediments press down on the layers beneath (Compaction) Point C: Dissolved minerals flow between the particles and cement them together (Cementation) Sedimentary Transformations

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34 Metamorphic Rocks Metamorphic Rocks…are formed when an existing rock is partially melted, squeezed, or both QUESTION???  What rock type does metamorphic rocks come from?

35 Metamorphic rocks are rocks that have "morphed" into another kind of rock. These rocks were once igneous or sedimentary rocks.

36 How do sedimentary and igneous rocks change? The rocks are under tons and tons of pressure, which fosters heat build up, and this causes them to change. If you exam metamorphic rock samples closely, you'll discover how flattened some of the grains in the rock are.

37 REVIEW Geologists classify rocks by observing color, texture and mineral composition. Geologists classify rocks by observing color, texture and mineral composition. There are 3 general classes of rocks: Igneous, Sedimentary, and Metamorphic. There are 3 general classes of rocks: Igneous, Sedimentary, and Metamorphic.

38 Igneous Rocks Igneous Rocks… are formed when lava and magma crystallize to form solid rock. There are 2 forms of Igneous Rocks Intrusive Intrusive Extrusive Extrusive

39 Sedimentary Rocks Sedimentary Rocks…are formed when sediments (sand clay, and silt) are compressed and become solid rock Sedimentary Rocks can be formed in 4 ways: Erosion Erosion Deposition Deposition Compaction Compaction Cementation Cementation

40 Metamorphic Rocks Metamorphic Rocks…are formed when an existing rock is partially melted, squeezed, or both Metamorphic rocks are formed from Igneous and Sedimentary rocks under extreme: Heat Heat Pressure Pressure

41 What type of Rock?

42 SEDIMENTARY!

43 What type of Rock?

44 METAMORPHIC!

45 What type of Rock?

46 IGNEOUS!

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48 What is any trace, mark, or remains of an organism called?

49 Fossils The remains or imprints of living things of the past found in Sedimentary rocks.

50 Fossils provide information about life and conditions in the past.

51 Fossils of Sea Creatures Oceans once covered the area Oceans once covered the area What part of the ocean What part of the ocean

52 Fossils of Plants Plant fossils can tell us about the ancient environment Plant fossils can tell us about the ancient environment

53 Animal Fossils Animal fossils can tell us About past environmentsAbout past environments What the animal ateWhat the animal ate How they livedHow they lived

54 How old must a fossil be? 10,000 years Now that’s old!!

55 What kind of rock are fossils usually preserved in?

56 Why do scientists study fossils? They study them to learn about extinct plants and animals.


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