Transcript Metamorphic rocks

Metamorphic Rocks
from Greek word meaning
“to change form”
made FROM igneous, sedimentary,
and other metamorphic rocks
called “daughter” rocks because they
are created from existing
“parent” rocks
Formation of Metamorphic Rocks
• Heat (more than 150 ºC)
• Pressure (more than 1500 bars), and
• Chemical change
– Some minerals ONLY form under conditions
of extreme heat and pressure.
– These are called “index” minerals.
• 12 – 16 kilometers (7.5 – 10 miles) below
Earth’s surface
Parent → Daughter
granite
igneous
→
gneiss
metamorphic
Parent → Daughter
limestone
sedimentary
→
marble
metamorphic
Parent → Daughter
phyllite
metamorphic
→
schist
metamorphic
Dynamic Metamorphism
• forms most metamorphic rocks
• occurs during mountain building and plate movement
• occurs in large areas so called regional metamorphism
Contact Metamorphism
• magma forces its way
into a layer of rock
and heats the existing
rock
• called thermal
metamorphism
• hot gases and liquids
cause structural and
chemical changes
• occurs in small areas
so it is called local
metamorphism
Metamorphism
Rocks DO NOT
MELT during
metamorphism.
Only igneous
rocks form from
molten rock.
Why here?
If fossils survive in metamorphic
rock, they tend to be deformed.
ammonite in slate
orthoceras in marble
Foliation
Dynamic Metamorphism
Existing rocks are
subjected to intense heat
and pressure that makes
the new rock more dense
and less porous.
This process produces
rocks in which the mineral
grains are flattened and
arranged in parallel layers
or bands. These rocks are
said to be foliated. The
rocks will split along these
layers into thin sheets.
Contact Metamorphism results
in Non-foliated rocks
The mineral crystals are arranged randomly
and the rocks do not split into layers.
Gemstone Formation
Gemstones
associated with
metamorphic
rock include the
beryls, jade,
lapis lazuli,
turquoise,
spinel, ruby,
sapphire and
zircon.
Marble is a good choice for sculpture and architecture because
it can be cut and polished as desired.
“Marblehouse” in Newport, RI built by
the Vanderbilts.
the Pieta by Michaelangelo
Yule Marble Quarry, Marble, Colorado is located
at 9,500 feet above sea level on a very steep
mountainside.
In 1931, stone from the Yule quarry was
selected for the Tomb of the Unknown
Soldier at Arlington National Cemetery.
In 1999, the quarry provided materials to
the Veteran Administration for headstones
in the national cemetery.
Slate – What
characteristic
does it have
that makes it
useful?
Slate is useful because it breaks
into flat pieces.
Can you use slate for sculptures?
US Supreme Court, Washington, DC
Taj Mahal, India
President Lincoln
The Parthenon in Greece
Marble Caves at General Carrera Lake, Chile, off of the Patagonian Andes.
These swirling marble walls were formed by 6,000 years of crashing waves
eroding the stone.
Marble Canyon
Death Valley, Nevada