WednesdayFebruary 6, 2013(Discussion and
WS – Metamorphic Rocks)
The Launch PadWednesday, 2/6/13
Name the following sedimentary rocks.Conglomerate
Breccia
SandstoneShale
Coquina Coal
AnnouncementsNational Girls & Women in Sports
Day!
AnnouncementsI will be available after
school today until 4:45.
Assignment Currently Open
Summative or
Formative?Date Issued Date Due Date Into
GradeSpeed Final Day
Quiz 16 S1 1/18 1/18 1/24 FRIDAY
Quiz 17 S2 2/1 2/1 2/1 2/15
WS – Sedimentary
RocksF9 2/4 2/5 FRIDAY
Lab – Sedimentary
RocksF10 2/5 2/6 FRIDAY
Recent Events in ScienceEarth Safe from Asteroid's Close Flyby Next Week
Read All About It!www.space.com/19624-asteroid-2012-da14-flyby-earth-safe.html
An asteroid will give Earth a historically close shave next week, but there's no
chance that the space rock will slam into our planet on this pass, experts say.
The 150-foot-wide (45 meters) asteroid 2012 DA14 will zoom within 17,200 miles (27,700
kilometers) of our planet on Feb. 15, coming nearer than the ring of satellites in
geosynchronous orbit. While the flyby will be the closest ever known in advance for
such a large asteroid, there's no reason to retreat to the doomsday bunker.
"NASA's Near-Earth Object Program Office can accurately predict the asteroid's path with the observations obtained, and it is
therefore known that there is no chance that the asteroid might be on a collision course with Earth," officials at the space agency's
Jet Propulsion Laboratory in Pasadena, Calif., wrote in a statement Friday (Feb. 1).
Metamorphic Rocks Metamorphic rocks are those that have
changed their form due to external environmental issues.
Metamorphic rocks are produced from preexisting igneous, sedimentary, or even
other metamorphic rocks. Metamorphism takes place where preexisting
rock is subjected to temperatures and pressures unlike those in which it formed.
There are different degrees of metamorphism which can be seen in the rock’s texture and in
its mineralogy.An example of low-grade metamorphism is
shale becoming slate. In high-grade metamorphism, obliteration of
the rock’s original features occurs.
Metamorphic Rocks There are two basic types of rock metamorphism:
thermal or contact metamorphism
regional metamorphism
Metamorphic Rocks Contact metamorphism is a type of metamorphism in which the
mineralogy and texture of a body of rock are changed by exposure
to the pressure and extreme temperature associated with a
body of intruding magma.
Contact metamorphism often results in the formation of
valuable minerals, such as garnet and emery, through the
interaction of the hot magma with adjacent rock.
Metamorphic Rocks During mountain-building, great quantities of rock are subjected to directed pressures
and high temperatures associated with large-scale deformation called regional
metamorphism.Regional metamorphism is a type of
metamorphism in which the mineralogy and texture of rocks are changed over a wide
area by deep burial and heating associated with the large-scale forces of plate tectonics.In regional metamorphism, rocks that form closer to the margin of the tectonic plates, where the heat and pressure are greatest, often differ in their minerals and texture
from those that form farther away.
What Drives Metamorphism?The driving agents of metamorphism include:
•heat
•pressure (stress) from burial (confining pressure) or from differential stress during mountain building
•chemically active fluids (mainly water and other volatiles)
Pressure as a Metamorphic Agent
Metamorphic TexturesThe degree of metamorphism is reflected in the rock’s texture and
mineral composition.When rocks are subjected to low-grade metamorphism, they become
more compact and more dense (like slate.)With high-grade metamorphism, stress causes certain minerals to re-crystallize. Consequently, many metamorphic rocks consist of visible
crystals, much like coarse-grained igneous rocks.
Metamorphic TexturesThe crystals of some
minerals will recrystallize with a
preferred orientation, essentially
perpendicular to the direction of the
compression force.
The resulting mineral alignment usually gives
the rock a layered or banded appearance
termed foliated texture. Example:
gneiss
Metamorphic TexturesSome metamorphic rocks
have a nonfoliated texture.
Metamorphic rocks composed of only one
mineral that forms equidimensional crystals are, as a rule, not visibly
foliated (examples: quartzite and marble.)
Common Metamorphic Rocks
Classification of Metamorphic Rocks
WorksheetMetamorphic Rocks