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EARTH SCIENCE - (CH.6)
ROCKS
10.1 Rocks and the Rock Cycle
✧Magma,
✦In time, the rock formed from the original magma is altered many times.
✧Three Major Types of Rock
✧1)
✦Studies of volcanic activity provide information.
✲
✧2)
✦Rock, minerals, and organic matter that have been broken into fragments are
known as ________________________.
✲Sediment is carried away and deposited by
✲Sedimentary rock form when sediment deposits
✧3)
✦Certain forces and processes, including
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✲The existing rock can thus be changed into metamorphic rock.
✧Any of the three major types of rock ____________________________________
✧Various geological forces and processes cause rock to change from one major type to
another and back again.
✦This series of changes is called the
✧
✧
When magma cools and hardens, it forms igneous rock.
There are two groups of igneous rocks.
✧They are classified according to where the molten rock cools and hardens:
✦1)
✲
✲
✧2)
✦
✧Intrusive and extrusive igneous rocks differ mainly in the
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✦The size of the crystalline grains in igneous rock is called its ________________.
✲The texture of igneous rocks is largely determined by the cooling rate of the
magma or lava that formed the rock.
✧Texture of Igneous Rocks
✦Intrusive igneous rocks:
✧
Intrusive igneous rocks
✲Example:
✱_______________________________________ is primarily granite
✧ Extrusive igneous rocks:
✦
✲The rapid loss of heat to air or sea water does not allow time for large crystalline
grains to form, and it produces _______________________________.
✲
✱Example:
✲ ___________________________________________ is composed of basalt.
✧Some intrusive igneous rocks form from magma that cools slowly at first and then
more rapidly as it nears the surface.
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✲This type of cooling produces ____________________________________________
✱Example:
✧Extremely rapid cooling produces a kind of igneous rock in which crystals were
_____________________________________.
✦Example:
✧During extremely rapid cooling, gases escaping from the molten material may
become trapped in the rock and form ____________________________.
✦Example:
The mineral composition of an igneous rock is determined by the
______________________________________________ from which the
rock develops.
✧1)
✦Form from magmas called __________________, which are high in ____________.
✦Have the light coloring of their main mineral components,
__________________________________________________________________
✦May also contain
✲Members of this family:
✧2)
✦Form from magmas called ________________________, which are low in
___________________________but rich in __________________.
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✦The main mineral components are
✦Also include dark-colored _________________________________________ such
as
✧These three components, along with ____________, give basaltic rocks a dark color.
✧The dark gray or black extrusive rock known as _________________ is a finegrained member of this family.
✧Coarse-grained intrusive _________________________ is also in this family.
✧3)
✦Made up of the minerals
✦Include little or no ______________________.
✦Coarse-grained __________________ and the fine-grained ________________are
members of the diorite family.
✧The underground rock masses made up of intrusive igneous rocks are called
____________________________________.
✧The surface rock masses made up of extrusive igneous rocks are called
_____________________________________.
✧___________________________________________: The _______________ of all
intrusions.
✦ Batholiths are very large masses of igneous rock that cover ___________________.
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✲Batholiths form the cores of many _________________________________
✱Example:
✲The largest batholith in North America forms the core of the
_________________________________________________________.
✧
A stock is an intrusion similar to a batholith that covers __________________
✧
When magma flows between rock layers and spreads upward, it sometimes pushes
the overlying rock layers into an _______________________.
✧The floor of the intrusion is parallel to the rock layer beneath it.
✦This type of intrusion is called a _________________________________
✦Laccoliths are frequently found in groups.
✱Example:
✧When a sheet of magma flows between the layers of rock and hardens, a __________
is formed.
✦ A sill _______________________________ to the rock layers surrounding it,
even if the layers are tilted.
✲Example:
✧Magma sometimes forces its way through rock layers by following existing
vertical fractures or by creating new ones.
✦A _______________________ is formed when the magma solidifies.
✲Dikes differ from sills in that they __________________________rock layers.
✲Dikes are common in areas of _______________________________________.
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✧When ___________________ erupts onto the earth's surface, it often forms a
_______________________________.
✦A volcano is
✦Eventually the softer parts of the cone are carried away by
___________________________________, and only the hard, solidified rock in
the vent remains.
✧The solidified central vent is called a _____________________________________.
✦Example:
✲Many extrusions are simply flat masses of rock called __________________.
✧Some extrusions take the form known as a _______________________________.
✦A lava plateau develops from lava that flows out of long cracks in the earth's
surface. The lava then spreads over a vast area, filling in valleys and covering
hills.
✲When the lava hardens, it forms a plateau.
10.3 Sedimentary Rock
✧Sedimentary rock is made up of accumulations of various types of sediments.
✧____________________________________________________ are the processes
that form sedimentary rock.
✧____________________________________:
The weight of overlying sediments
causes pressure, pushing the fragments together and squeezing out air and water
from the fragments.
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✧___________________________________: Water carries dissolved minerals through
the sediments. These minerals are left between the fragments of sediment and
provide a cement to hold the fragments together.
✧
Geologists classify sedimentary rocks according
✧1) ______________________________________________: Is made up of rock
fragments carried away from their source by water, wind, or ice and left as
deposits elsewhere. Over time, the separate fragments may become compacted
and cemented into solid rock.
✦______________________________________________ is the rock that is formed
from these deposits.
✲Clastic sedimentary rocks are _________________________________________
✧A.
_________________________________: Rock composed of rounded gravelsized fragments, or pebbles.
✦1. If the fragments are angular and have sharp
comers, it is called a
___________________________.
✲In conglomerates and breccias, the individual pieces of sediment can be easily
seen.
✧B. ___________________________________: Is made up of sand-sized
grains that
have been cemented together.
✦_____________________________ is the major component of sandstone.
✲Many sandstones have pores between the sand grains through which liquids,
such as groundwater and crude oil, can move.
✧C. _____________________________: Consists of clay-sized particles cemented
and compacted under pressure.
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✦The flaky clay particles are usually pressed into flat layers that will split apart.
✧2) _____________________________________________: Forms from minerals
that have been dissolved in water.
✦Some form from dissolved minerals that precipitate, or settle, out of the water as a
result of a change in temperature.
✲Example:
✧Another type of sedimentary rock results when
✦The dissolved minerals left behind form rocks called _______________________.
✲Examples:
✧3) _______________________________________________: Forms from the
remains of organisms.
✦Means "______________________________________________________”"
✲Examples:
✧Formation of organic limestones begins when the mineral _____________________
is removed from sea water by marine organisms, such as coral, clams, oysters,
and plankton. (How is calcite used in theses animals??)
✧
______________________: limestone made up of the shells of tiny, one-celled
marine organisms
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✦Example:
✧1)
✦_____________________________, or stratification, of sedimentary rock occurs
when there is a change in the kind of sediment being deposited.
✲Most water-deposited strata are laid down ___________________________,
some sediments deposited by wind, such as sand dunes, are characterized by
_____________________________________.
✧2)
✦ Ripple marks are formed by __________________________________________.
✲When the sand becomes _________________________________, the ripple
marks may be preserved.
✧______________________________________ result when muddy deposits dry and
shrink.
✦The shrinking causes the dried mud to crack.
✦
✧3)
✦Fossils are the
✲They are usually preserved in __________________________________.
✲
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✲Even the harder parts dissolve, leaving only ____________________________
in the rock.
✧4)
✦ Sedimentary rocks sometimes contain
✲These nodules are known as _______________________________.
✱Concretions form
✧Groundwater can deposit dissolved quartz or calcite inside cavities in sedimentary
rock.
✦ The ___________________________________________crystallizes in the
cavity of the rock .
✲The crystal cavities are called ________________________________
10.4 Metamorphic Rock
✧
✧Most metamorphic rock forms _________________ beneath the surface of the earth.
✧All metamorphic rock is formed from existing
✧__________________________________________________ can cause certain
minerals to change into other chemicals.
✧Minerals may also change in _____________________________________________
that give the rock a __________________________ appearance.
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✧Two types of metamorphism occur in the crust of the earth:
✦1)
✦2)
✧When hot magma pushes through existing rock, the heat from the magma can change
the structure and mineral composition of the surrounding rock.
✦This is called _______________________________________________________
because only rocks near or actually touching the hot magma are metamorphosed
by its heat.
✧
Metamorphism sometimes occurs over an area of thousands of square kilometers
during periods of tectonic activity.
✦This is called
✧Metamorphic rocks are classified according to their structure.
✦They have either a ___________________________structure or an
____________________________________structure.
✲Rocks with a foliated structure
✲Rocks.
✧Foliated rocks can form in one of two ways:
✦1)
✦2)
✱Examples:
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✦A greater amount of heat and pressure change ____________________ into the
coarser-grained metamorphic rock known as ________________________
✲This greatly metamorphosed rock with bands of light and dark minerals is
________________________________________.
✧Nonfoliated metamorphic rocks do not have bands of crystals.
✦Example:
✲_______________________________________ is a metamorphic rock formed
from the compression of _______________________________.
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