Download stAIR Project

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stAIR Project
By: Sarah Barnes
 Introduction
All rocks change slowly from one type to another,
again and again. The changes form a cycle, called
"the rock cycle."
The way rocks change depends on various
processes that are always taking place on and
under the earth's surface. Now let's take a closer
look at each of these processes.
Heat
Deep below the earth's surface, temperatures are hot enough to
melt most rocks. However, before the melting point is reached, a
rock can undergo many changes while in a solid state — changing
from one type to another without melting.
 Pressure
An additional factor that can transform rocks is the pressure caused
by tons of other rocks pressing down on it from above.
Heat and pressure usually work together to alter the rocks under the
earth's surface. This kind of change is called metamorphism which
results in a metamorphic rock.
 Click here to see the heat and pressure video:
http://screencast.com/t/PCA0IxoNjtB
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Melting
The high temperatures required to melt a rock are generally found only deep within
the earth. It takes temperatures between 600 and 1,300 degrees Celsius (1,100
and 2,400 degrees Fahrenheit) to melt a rock, turning it into a substance called
magma (molten rock).
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Cooling
Liquid magma also turns into a solid — a rock — when it is cooled. Any rock that
forms from the cooling of magma is an igneous rock. Magma that cools quickly
forms one kind of igneous rock, and magma that cools slowly forms another kind.
Extrusive Igneous
When magma rises from deep within the earth and explodes out of a volcano, it is
called lava, and it cools quickly on the surface. Rock formed in this way is called
extrusive igneous rock. It is extruded, or pushed, out of the earth's interior and cools
outside of or very near the earth's surface.
Intrusive Igneous
Magma that gets pushed up toward the earth’s surface cools at a much slower rate
than lava. The kind of rock formed in this way is called intrusive igneous rock. It
intrudes, or pushes, into the earth's interior and cools beneath the surface.
 Click here to see the melting and cooling video:
http://screencast.com/t/HE4w6byZdpU
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Weathering
Weathering, such as rain or wind, cause rocks to get eroded or
broken down into smaller pieces. These small pieces of rock
form the sediment that creates sedimentary rock.
 Compacting
As these little pieces of sediment get compacted together, they
eventually for a sedimentary rock.
 Click here to see the weathering and compacting video:
http://screencast.com/t/caGU3MMT
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http://www.learner.org/interactives/rockcycle/types.html
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Rocks are not all the same!
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The three main types, or classes, of rock are sedimentary, metamorphic, and igneous and the
differences among them have to do with how they are formed.
Sedimentary
 Formed from particles of sand, shells, pebbles, and other fragments of material.
 These particles or sediments accumulate and harden into rock.
 You can often see sand, pebbles, fossils or stones in the rock.
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Examples of this rock type include conglomerate and limestone.
Metamorphic
 Formed under the surface of the earth
 Go through metamorphosis (change) that occurs due to intense heat and pressure (squeezing).
 Usually have ribbon like layers and may have shiny crystals.
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Examples of this rock type include gneiss and marble.
Igneous
 Formed when magma or lava cools and hardens.
 When lava cools very quickly, no crystals form and the rock looks shiny and glasslike.
 Sometimes gas bubbles are trapped in the rock during the cooling process,
leaving tiny holes and spaces in the rock.
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Examples of this rock type include basalt and obsidian.
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Here's a chart of some of the key characteristics that
can help you identify the rocks within these three
main classes.
Sand or pebbles
Individual stones,
pebbles, or sand
grains visible in the
rock.
Fossils
Imprints of leaves,
shells, insects, or
other items in the
rock.
Sedimentary
Gas bubbles
"Holes," like Swiss
cheese, in the rock.
Glassy surface
A shiny and smooth
surface, like colored
glass.
Ribbonlike layers
Straight or wavy
stripes of different
colors in the rock.
Crystals
Small, flat surfaces
that are shiny or
sparkly, like tiny
mirrors
.
Igneous
http://www.learner.org/interactives/rockcycle/types.html
Metamorphic
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To take the quiz hit the start button. If you don’t feel ready to take the quiz
and need to look over the information more, press the back arrow.
 Which
type of rock is
this?
metamorphic
sedimentary
igneous
WRONG!
Click this button to try
again:
Correct!
You can tell that this rock is igneous because of its
shiny, glasslike surface.
 Which
type of rock is
this?
metamorphic
sedimentary
igneous
WRONG!
Click this button to try
again:
Correct!
You can tell that this rock is sedimentary because
it has large chunks of other rocks in it.
 Which
type of rock is
this?
metamorphic
sedimentary
igneous
WRONG!
Click this button to try
again:
Correct!
You can tell that this rock is metamorphic
because of the rippled layers.
 Which
type of rock is
this?
metamorphic
sedimentary
igneous
WRONG!
Click this button to try
again:
Correct!
You can tell that this rock is sedimentary
because you can see fossils embedded in the
rock.
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Hopefully you have learned a lot about the rock cycle!
Information and videos from:
http://www.learner.org/interactives/rockcycle/types.html