november 29, 2018process by the earth that causes rocks to rise to the surface weathering water,...
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Chapter 3 Rocks: Mineral Mixtures
Section 3.1: The Rock Cycle
Objectives1. What is a rock?2. What are the three major types of rock?3. What is the rock cycle?4. How do igneous, sedimentary, and metamorphic rocks
differ?5. What processes transform rocks from one type to another?
PreLab1. Look carefully at your rock samples.2. Observe and record at least 3 ways the rocks are similar.3. Observe and record at least 3 ways the rocks are different.4. Classify the rocks into three groups based on your observations.5. Give reasons for these groupings.
After you have your groupings, 1. How does your classification scheme compare (same/different) with at least two other groups.2. Each of these rocks used today, belongs to one of the three major groups of rocks. Hypothesize what makes one group of rocks different from the others.
Many of us work hard to recycle the items we use in our daily lives to reduce the impact we have on the environment. In a way, the Earth also recycles through the rock cycle. Can you imagine what a rock might look like through each stage of the rock cycle?
How do rocks differ from minerals?minerals combine to form rocks
What are rocks?Minerals make rocks, but not all rocks are made of minerals!a naturally occurring, solid mixture of one or more mineralssome rocks are only made of 1 mineral Limestonesome rocks are made of no minerals Coal
What are rocks used for?tools, buildings, roads
Rocks are made through a ROCK CYCLE. The rock types includedin the rock cycle are igneous, sedimentary, and metamorphic.
Rock Cyclea series of processes in which rocks continuously change from
one type of rock to another
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Processes That Shape the Earth
Igneous RockHeat
soften rockMelting
rock melts into molten material (melted rock)Magma
melted rock underground
Coolingmagma begins to cool and mineral crystals begin to join
togetherSolidification/Crystallization
cooled magma hardens and becomes a solid
Sedimentary RocksUplift
process by the Earth that causes rocks to rise to the surface
Weatheringwater, wind, ice and heat break down rocks into sediments
chemical weatheringthe minerals in rocks are dissolved into the rainwater or
changed from one type of mineral into another
warm, moist environments have more chemical weathering because water is needed for the chemical changes and
warmth facilitates the reactions.
physical weatheringrocks are mechanically broken apart into smaller pieces
if water freezes into cracks in a rock it will expand as it freezes, opening the crack even more.
Sedimentssmall pieces of broken down rock, mineral fragments,
mineral grains
Erosiontransportation of sediments from one location to another
Depositionmaterial is placed down after erosion occurs
Lithificationprocess of sediment becoming a rock
sediment that has formed, been transported, and deposited, is not a sedimentary rock unless it is allbound together
Cementationsediments become cemented together
Compactionsediments becoming squeezed together
Metamorphic RockHeat/Pressure/Chemical Reaction (rxn)
soften and squeeze the rock
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Section 3.2 Igneous Rocks
Key ObjectivesHow are intrusive and extrusive igneous rocks alike and different?How does the rate of cooling affect an igneous rocks texture?How are igneous rocks classified according to composition?
Do you think rocks that cooled and solidified from lava on Earth’s surface would look different from those that cooled and solidified from magma inside the Earth?Why?
Igneous Rocksigneous = firerocks form when magma or lava cools and solidifiesformation of different igneous rocks depends on how long it takes
for the magma or lava to cool and the composition of the magma or lava
Intrusive Igneous Rockrock formed from the cooling and solidification of magmabeneath the Earth's surfacemostly coarsegrained texture
Extrusive Igneous Rocklava that cools and solidifies on or near the Earth's surface
Rocks are further classified by composition and texture.
Texturebased on the sizes, shapes, and positions of the rock’s grains
finegrainedneed magnifying glass or microscope to see mineral grainsrapid cooling
coarsegrainedlarge crystals to formslow cooling
glassylava cools so fast that the grains do not have time to get
together
porphyritic minerals do not crystallize at the same rate
Compositionchemical makeup of a rockdescribes the mineral or other materials
in the rock
Graniticlight coloredquartz/feldsparsFelsic
lightcolored igneous rocks
BasalticdarkcoloredMafic
darkcolored igneous rocks
Andesitic cross between basaltic and granitic compositions
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3.3 Sedimentary RocksKey Concepts
What are the major processes involved in the formation of sedimentary rocks?
What are the three types of sedimentary rocks?What features are unique to some sedimentary rocks?
How are layers in a sedimentary rock similar to the rings in a tree?
How are they different?
In Canada and the North United States, the growing season begins in the spring. At first, the cambium produces numerous large cells with thin walls that form the springwood (earlywood). If you look at a cross section of a tree, this is the lightcolored ring.Then, towards the end of the summer, growth slows down. The cells manufactured at this time of year are small, with thick walls. They form the summerwood (latewood) which appears as a darker ring on the tree cross section.One year of growth is therefore represented by a ring consisting of a light part and a dark part. The darker wood is not formed in winter, as some people believe, because the cambium is completely inactive in the winter.The following year, a new twopart ring is added. The older rings are closest to the center of the tree. The tree grows in diameter because it manufactures new cells around its circumference, not because the old cells get larger.The old annual rings form the heartwood of inactive cells: this is the dead part of the tree Xylem. The live portion Phloem includes only the most recent rings. Depending on the tree's age and species, this portion is 1.5 to 7.5 cm wide. The dead wood is the largest part of the tree. Often, it takes on a darker colour.
Sedimentary Rocks75 % of Earth’s surface = sedimentary rocksform from sediments become pressed together
or cemented together = lithificationsediments = loose material
ex: rock fragments or mineral grains weathering process that breaks rocks into pieceserosion moves sediments to a new locationdeposition laid down or dropped out of the liquidstrata layers in the sedimentary rocksstratification process in which sedimentary rocks are
arranged in layers
Two ways sedimentary rocks form Lithification* Compaction
layer on layer pressure sediments stick together
* CementationWater soaks through sedimentsquartz and calcite dissolves and acts as a cement sediments stick together
Classification of Sedimentary Rocks1. Clastic
* made of broken fragments
breccia = sharp angles conglomerate = rounded angles
2. Chemical * minerals dissolve in solution (HCL)
ex: rock salt * limestone fossils, usually deposited on the ocean
floor
3. Organic or Biochemical Sedimentary * rocks form from remains of living items
ex: fossil rich limestone chalk is made from tiny marine creatures
Look at table 2 Page 79 Classification of Major Sedimentary Rocks
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3.4 Metamorphic RocksKey Concepts
Where does most metamorphism take place?How is contact metamorphism different from regional
metamorphism?What are three agents of metamorphism, and what kinds of
changes does each cause?What are foliated metamorphic rocks, and how do they form?How are metamorphic rocks classified?
Metamorphic Rocks* meta = change* morphos = shape* deformation = change in the shape of a rock caused by
a force place on it* formed from heat, pressure, and chemical rxns * mineral grains can flatten
How they can form? page 107Contact Metamorphism
when rocks are heated by magma near by
Regional Metamorphismwhen pressure and temperature builds up and causes
changes in rocks
Two Textures of Metamorphic Rocks1. Foliated
* mineral grains flatten and line up in parallel bandsexample: gneiss from granite (igneous)
2. Nonfoliated * mineral grains change but do not form bands
example: marble from limestone (sedim)
Limestone Marble
Explain why marble rarely contains fossils even though limestone does.