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Rocks Rocks! What makes up Earth’s Crust Three types of rocks… Igneous Metamorphic Sedimentary.

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Presentation on theme: "Rocks Rocks! What makes up Earth’s Crust Three types of rocks… Igneous Metamorphic Sedimentary."— Presentation transcript:


2 Rocks Rocks! What makes up Earth’s Crust

3 Three types of rocks… Igneous Metamorphic Sedimentary

4 What is a rock? What is a rock? A rock is a solid that forms in nature. It may have one or more types of minerals within it (or no minerals at all).

5 Some rocks have minerals, some don’t… Minerals are clearly visible in some igneous rocks like….. There are no mineral crystals in obsidian.

6 What is the rock cycle? Natural processes that… Forms Changes Breaks down rocks  Rock is reformed into another type of rock.

7 The rock cycle in action… The rock cycle in action… The rock cycle shows the three types of rocks.  Igneous  Metamorphic  Sedimentary Listen and watch how the processes formed the three types of rocks.

8 Forms when molten rock cools and becomes a solid. Igneous rocks may form inside Earth or on Earth’s surface.  Intrusive-forms when magma cools within the Earth.  Extrusive-forms when lava cools on the surface. Igneous Rock

9 What is a rock’s texture? Texture refers to the size of the mineral crystals: coarse, fine, glassy Pumice Coarse Fine Glassy

10 Textures of Intrusive Igneous Rock The size of mineral crystals depends on how quickly the magma or lava cooled. The high temperatures of the interior of the Earth causes magma to cool slowly. Slow cooling allows large crystals to form. Intrusive Rocks

11 How are we able to see intrusive rocks? Ship Rock formed 30 million years ago. Magma cooled to form intrusive rock. Intrusive igneous rock has been left as weaker rock (like sedimentary) has worn away due to weathering & erosion.

12 Textures of Extrusive Igneous Rock The surface of Earth is much cooler than the interior, causing lava to cool quickly. There is no time for large mineral crystals to form.

13 Composition of Igneous Rocks… Most igneous rocks are made up of silicate materials The color tells you how much silica the rock has. High levels of silica will be lighter in color. Low levels of silica will be darker in color.

14 What type of rock was carved to create Mount Rushmore? Igneous!

15 Interesting Rock Formations #1 #2 #3 #4

16 Which of these is a rock? A. haliteB. granite C. micaD. quartz Answer: B. granite Which is formed from cooling magma? A. metamorphicB. igneous C. sedimentaryD. sandstone Answer: B. igneous

17 Sedimentary Rocks: “something that settles” Small pieces of rock turn into pebbles, gravel, sand, clay, and plant & animal matter. They tumble down rivers and streams. These pieces settle in a new place and begin to pile up and the sediments form flat layers.

18 Sediments harden into rock in two ways. Compaction- layer after layer of sediments are deposited, they are pressed together tightly to form rock. Cementation- sediments are held together by minerals that have crystallized between them (acting as cement).

19 Sedimentary rocks may be rich in…. Fossils- Remains or trace of an organism from long ago. Coal-Made up of the remains of dead plants. The coal we use today formed millions of years ago in swamps. Limestone-made of carbonate minerals (calcite) from seashells that settle on the bottom of the ocean.

20 COAL: Natures rock….. Coal is made from dead plants and over time pressed into the Earth.

21 Sedimentary Rock tells a story about Earth’s past… These rocks are laid down in layers with the oldest on the bottom. Do you remember what rock layers are called? Law of Superposition or stratification!

22 Do you remember? What layer of rock is the… Oldest? Oldest Youngest

23 Metamorphic Rock= Changed Rock SedimentaryMetamorphic

24 Composition and Texture: a way to identify metamorphic rock  When mineral grains line up in parallel layers, the metamorphic rock is said to have a Foliated texture. SlateGneiss

25 Non Foliated Metamorphic Rock Typically made up of one type of mineral so different minerals can not line up in bands. Marble formed from limestone Quartzite forms from Sandstone When a metamorphic rock does not have “foliation” it typically has only one mineral, therefore no parallel banding patterns.

26 Metamorphic Rocks are formed when… + Metamorphic Rock = +

27 How much of Earth’s Crust is made of each type of rock? Surface = 75% Sedimentary RockEntire Crust = 95% Igneous and Metamorphic Rock

28 What type of rock is the most common on the surface of Earth’s crust? A. metamorphicB. sedimentary C. igneousD. igneous and metamorphic Answer: D igneous and metamorphic 95% of Earth’s entire crust consist of what type(s) of rock? A. metamorphicB. igneous C. sedimentaryD. sandstone Answer: C. sedimentary

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