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metamorphic rocks

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metamorphic rocks ESRT page 7 Key ideas Formed when existing rocks are changed by HEAT & PRESSURE, forming new, larger, denser crystalline structures The new rocks ... – PowerPoint PPT presentation

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Title: metamorphic rocks


1
metamorphic rocks
  • ESRT page 7

2
Key ideas
  • Formed when existing rocks are changed by HEAT
    PRESSURE, forming new, larger, denser crystalline
    structures
  • The new rocks resemble the parent rock

3
  • Parent rock Preexisting rock
  • Recrystallization A process in which rocks
    undergo change without truly melting

4
More Key Ideas
  • IMPORTANT- THE ORIGINAL ROCK CANNOT MELT WHEN IT
    BECOMES METAMORPHIC! (If it melts, its igneous!)
  • Metamorphism

5
Types of metamorphism
  • REGIONAL Large areas of rock are changed by HEAT
    PRESSURE

6
Metamorphic mountains formed from regional
metamorphism
7
  • CONTACT
  • Magma touches layers of rock and the HEAT causes
    the rock layers to change

8
Alaskas Copper Mountain contact metamorphism
9
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10
the bells whistles for metamorphic rock
identification
  • BANDING alternating layers of different colored
    minerals due to sorting by density
  • These bands are usually distorted from the heat
    pressure
  • not to be confused with sedimentary layers!!!!!!

11
Stratification (sed) vs. Banding (metamorphic)
12
Stratification vs. Banding
13
FOLIATION
  • FOLIATION mineral alignment the minerals in
    the rock are layered, which facilitates breakage
    along flat planes- look for scratches in the
    rocks

14
More foliation slate phyllite
Foliation note the scratches in the rock
this is mineral alignment!
Excellent example of banding distortion this
is GNEISS ?
Banding mica schist
15
Difference Between Marble and Quartzite
  • -Both are white in color
  • Marble reacts with HCl acid and quartzite does
    not

16
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17
When I was young, liquid granite I was diagnosed
schizophrenic Neither feldspar, nor mica, nor
quartz But the sum of the three Bonded
igneously That means melted together for life
Well, I was hot and dejected Oh, I was injected
Under layers and layers of dirt But, it was
there that I changed All my crystals rearranged
Into G-N-E-I-S-S, gneiss So, take a look, and
you'll see That I'm not what I used to be I've
been touched metamorphically All the heat and
the pressure Have changed me forever So don't
take me for granite, I'm gneiss
The GNEISS SONG
Well, I wasn't to been seen Until time changed
the scene Exposing my face to the sun But, now
its here that I sit Being worn down bit by bit
Oh, erosion is wearing me down Refrain So, be
aware, have a look Underground or underfoot For
that beautiful pinky-gray face The Canadian
shield Holds a magnamous yield Of the rock that
was changed into gneiss Refrain
18
Okay
  • Lets sum up!

19
There are 3 classifications of ROCKS
  • Igneous formed by the cooling of magma (melted
    rock)
  • Sedimentary formed by compaction cementation
    of rock fragments
  • Metamorphic formed by heat pressure changing
    existing rocks

20
Remember the bells whistles when identifying
rocks!
  • Igneous obvious crystals of different minerals
  • Sedimentary stratification, fragments, fossils
  • Metamorphic foliation, banding
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