the rock cycle
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The Rock Cycle. Global Geography 12. http://www.learner.org/interactives/rockcycle/types.html. The Rock Cycle. T he rock cycle refers to the process of rock types changing into other types of rocks . There are three different types of rocks: Igneous rocks Sedimentary rocks - PowerPoint PPT PresentationTRANSCRIPT
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The Rock CycleGlobal Geography 12
http://www.learner.org/interactives/rockcycle/types.html
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The Rock Cycle
• The rock cycle refers to the process of rock types changing into other types of rocks.
• There are three different types of rocks:– Igneous rocks– Sedimentary rocks– Metamorphic rocks
Rock Cycle Videohttp://www.youtube.com/watch?v=SRaInMDNyE8
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Igneous Rocks• Igneous rocks are formed when magma (molten
rock) cools and hardens. • Sometimes the magma cools inside the earth; other
times it erupts onto the surface from volcanoes.• When lava cools very quickly, no crystals form and
the rock looks shiny and glasslike. • Sometimes gas bubbles are trapped in the rock
during longer cooling processes, leaving tiny holes and spaces in the rock.
• Examples of this rock type include granite, basalt, and obsidian.
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Igneous Rocks
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Sedimentary Rocks• 70% of all rocks on Earth are sedimentary rocks• Sedimentary rocks are formed from particles of sand,
shells, pebbles, and other fragments of material. • Gradually, this sediment accumulates in layers and over
a long period of time hardens into rock.• Generally, sedimentary rocks are fairly soft and may
break apart or crumble easily. • You can often see sand, pebbles, or stones in the rock• It is the rock type that most commonly contains fossils.• Examples include conglomerate and limestone.
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Sedimentary Rocks
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Metamorphic Rocks• The oldest known rock lies in Canada (NWT). The
Acasta gneiss, a metamorphic rock, is 3.96 billion years old. • Metamorphic rocks are formed under the surface of
the earth from the change that occurs due to intense heat and pressure.
• The rocks that result from these processes often have ribbon-like layers.
• They may have shiny crystals on their surface, formed by minerals growing slowly over time.
• Examples of this rock type include gneiss and marble.
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Metamorphic RocksSome examples of changes from one rock type into a metamorphic rock type due to high temperatures and pressures include…
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Metamorphic Rocks
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• Scientifically speaking it would be impossible to dig a tunnel through to the other side of the world.
• If you attempted to dig a hole to the other side of the Earth, you would be digging through:
» More than 12 000 kilometres of solid rock and molten magma» Rock reaching temperatures up to 6000 ºC » Extreme pressures up to 300 million times
greater than the pressures we experience on the surface of the Earth!
Digging Through Earth
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Digging Through Earth
• If you did manage to dig a hole through to the other side of the Earth, how long do you think it would take you if you were digging at a rate of 0.3 meters per minute (1 foot per minute)?
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Digging Through Earth
• Scientists have calculated the time it would take for you to dig a tunnel through to the other side of the Earth (at a rate of 1 foot per minute) at 87 years.
• If you did somehow manage to dig a hole to the other side of the Earth, would you fall through?
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Digging Through Earth
• Theoretically the answer is NO! • This is because gravity changes as you fall to
the Earth’s centre and friction would slow you down.
• However, if you ignored gravity and friction altogether, how long do you think it would take you to fall through the tunnel if you jumped in on one end of the Earth?
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Digging Through Earth
• Scientists think it would take about 42 minutes to fall through the Earth’s tunnel to reach the other side.
• If you started digging in Nova Scotia, where do you think you would end up coming out on the other side?
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If you started digging a tunnel in Nova Scotia through the centre of the Earth, you would come out to the south of Australia.
http://www.livephysics.com/ptools/dig-hole-through-earth.php
The Earth is not a perfect sphere. It is slightly flattened at the poles, and bulges a little at the equator due to the Earth’s spin.