What is the rock cycle and how are rocks formed?

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The rock cycle is a concept used to explain how the three basic rock types are related and how Earth processes, over geologic time, change a rock from one type into another. Plate tectonic activity, along with weathering and erosional processes, is responsible for the continued recycling of rocks.
2. The Life of a Rock
Layers of
Igneous Sedimentary Rock
Changes are made
Melted rock cools from pressure and
and hardens
3. Rocks become smaller, and smaller,
and smaller, and ...
• By erosion
• By wind
• By earthquake
• By floods
• By rain
• By slides
• By man
4. Terms to Know
• Weathering: the breaking up of
rocks and soil
• Erosion: the moving of weathered
rock and soil. Weathering allows
erosion to take place.
5. Products of Weathering
• Clay
• Sand
• Rock Fragments (pebbles and stones)
6. Rocks change…………..
• By earthquakes
• By volcanoes
• By heat and pressure
7. Sedimentary Rock is . . .
• Rock formed when
layers of small
particles of shell, rock,
and sand join
8. Sedimentary Rocks
How They are Made
• Wind and water break down the earth
• Bits of earth settle in lakes and rivers
• Layers are formed and build up
• Pressure and time turn the layers to rock
9. Types of Sedimentary Rocks
Sandstone Limestone
Gypsum Conglomerate
10. Fossils
• Fossils are usually found in sedimentary
rock and are the remains or imprints of
plants and animals that died long ago.
11. Fossils-Life From the Past
• Fossils provide information about life and
conditions of the past.
• Scientific evidence shows that the Earth is
approximately 4.5 billion years old
12. Metamorphic Rock is . . .
• Rock that is formed
when pressure and
heat create changes
to sedimentary or
igneous rock.
13. Metamorphic Rocks
What are They?
• Rocks that have changed
• They were once igneous or sedimentary
• Pressure and heat changed the rocks
14. Types of Metamorphic Rocks
Schist Gneiss
15. Igneous Rock is . . .
• Rock that is formed
when melted rock
cools and hardens.
16. Igneous Rocks
What are They?
• Fire Rocks
• Formed underground by trapped,
cooled magma
• Formed above ground when volcanoes
erupt and magma cools
17. Types of Igneous Rocks
Granite Scoria
Pumice Obsidian
18. Review of the Rock Cycle
• How are sedimentary rocks formed?
• What is a fossil?
• How are metamorphic rocks formed?
• How are igneous rocks formed?
• Give an example of each type of rock.
• What is weathering?
• Explain what erosion is.
19. Credits
• These slides were a compilation of work
• Jefferson County Schools Power Points
on Rocks
• http://jc-schools.net/PPTs-science.html
• Ellen Benegar (Suffolk Public Schools)