WednesdayFebruary 6, 2013(Discussion and

WS – Metamorphic Rocks)

The Launch PadWednesday, 2/6/13

Name the following sedimentary rocks.Conglomerate

Breccia

SandstoneShale

Coquina Coal

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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

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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