Rocks on Earth can be classified into three categories based on the way they were formed. Igneous rocks are formed through volcanic action. Sedimentary recks are formed by deposition. Metamorphic rocks are formed when existing rocks undergo a change due to extreme heat and pressure. Rocks that have a volcanic origin are classifed as igneous and form when magma or lwa cook and hardens. As the magma or lava cook; crystals begin to form. The size of the crystals depends upon how fast the magma or lawa cools. If magma cools quickly, small crystals form and can be observed on the rock surface, such as in basalt, for example. Lava can cool so quickly that crystals do nothave time to form at all, such as with obsidian. If mogma cools slowly. larger crystals form and can easily be seen on the surface of rock specimens. A common example of igneous rock that exhibits large erystal formation is granite. When Earth's materials are deposited in layers and pressed together over time, sedimentary rocks form. The formation of sedimentary rock begins with the deposition of sediments. As layers are added, the oldest or lower layers that were deposited first experience increased pressure. The sediments and the spaces between then are crushed together in a process cal ied conpaction. During the cementation process, the sediments are bound together when a solution fills in around the particles like glue. If the rediments deposited are sand particles, such as in a beach environment, sandstone forms. If the sediments are fine sit or clay-sited particles, commonly cal ed'mud;' such as those found in basins worldwide, shaie forms, thestone typically forms from shells and other sediments deposited in ocean environments. A quiet and undistubed ewironnent will sometimes lead to fossit formation vithin the Layers of sedimentary deposition. Metamorphic rock forms when one type of rock changes into another due to exposure to heat and pressure ofter cansed by morement of material deep beneath Carthis surface. This change to rock appearance and cemposition takes an entrenelylong tine. Metamorphle rocks are often characterized by wavy layers of mineral orytals or by the presence of unusual mincrals. Any rock can become a metamorphic rock. For example, the sedimentary rock ahule forms from layers of deposited sitt. When exposed to high pressure due to scologic processes. the metamorphic rock slate forms. The sedimentary rock sandstone changes to cuataite when exposed to extreme heat and pressure beneath Eath's surface. Another example of a metamorphic rock is mable. which forms when limestone is exposed to extreme temperatures or prescure. Igneous basalt changes to schikt in the metanorphic process. The interesting. thing about the motamorplic nrocess is that any rock-igneous, metamorphic, or seclinentary-will change and form now metamorphic rock given enough time, heat, andor pressure. The rock cycle llustrates how rocks move on and under Earth's crust and change from one typ.

1. Rocks on Earth can be classified into three categories based on the way they were formed.
Igneous rocks are formed through volcanic action. Sedimentary recks are formed by deposition.
Metamorphic rocks are formed when existing rocks undergo a change due to extreme heat and
pressure. Rocks that have a volcanic origin are classifed as igneous and form when magma or lwa
cook and hardens. As the magma or lava cook; crystals begin to form. The size of the crystals
depends upon how fast the magma or lawa cools. If magma cools quickly, small crystals form and
can be observed on the rock surface, such as in basalt, for example. Lava can cool so quickly that
crystals do nothave time to form at all, such as with obsidian. If mogma cools slowly. larger
crystals form and can easily be seen on the surface of rock specimens. A common example of
igneous rock that exhibits large erystal formation is granite. When Earth's materials are deposited
in layers and pressed together over time, sedimentary rocks form. The formation of sedimentary
rock begins with the deposition of sediments. As layers are added, the oldest or lower layers that
were deposited first experience increased pressure. The sediments and the spaces between then
are crushed together in a process cal ied conpaction. During the cementation process, the
sediments are bound together when a solution fills in around the particles like glue. If the
rediments deposited are sand particles, such as in a beach environment, sandstone forms. If the
sediments are fine sit or clay-sited particles, commonly cal ed'mud;' such as those found in basins
worldwide, shaie forms, thestone typically forms from shells and other sediments deposited in
ocean environments. A quiet and undistubed ewironnent will sometimes lead to fossit formation
vithin the Layers of sedimentary deposition. Metamorphic rock forms when one type of rock
changes into another due to exposure to heat and pressure ofter cansed by morement of material
deep beneath Carthis surface. This change to rock appearance and cemposition takes an
entrenelylong tine. Metamorphle rocks are often characterized by wavy layers of mineral orytals or
by the presence of unusual mincrals. Any rock can become a metamorphic rock. For example, the
sedimentary rock ahule forms from layers of deposited sitt. When exposed to high pressure due to
scologic processes. the metamorphic rock slate forms. The sedimentary rock sandstone changes
to cuataite when exposed to extreme heat and pressure beneath Eath's surface. Another example
of a metamorphic rock is mable. which forms when limestone is exposed to extreme temperatures
or prescure. Igneous basalt changes to schikt in the metanorphic process. The interesting. thing
about the motamorplic nrocess is that any rock-igneous, metamorphic, or seclinentary-will change
and form now metamorphic rock given enough time, heat, andor pressure. The rock cycle
llustrates how rocks move on and under Earth's crust and change from one type of rock into
another. As rocks move through the rock cycle. their mineral compositions and pheskal structures
chanes to reflect the processes under which they are formed. The rock eycle thons how any rock
can undergo change to form any other type of rock. For example, an ienecus reck formed by a
volcanic lava llow can crumble to become sand, the sand can be deposited on a beach and
eventually be compacted end cemerted to become the sedimentory rock, sunditone. The
sandstone can be buried deeo into Earth's crust where extreme pressure and heat from the
overhing layers change the sanditone into a metamorphil rock. Any rock cin be carried so deep
that the temperature becomes so great that the rock meiks, becomes magma, and is then ready to
move toward the surface to form new igneous rocks. Unike life cycles, rocks do not have to move
through each stage. An igneour rock can be durged into a metanomahic rock, a metamorphic rock

2. can crumble to become a sedimentary rock, and sedinentary rocks cas be re melted to become
magma The pathway a rock thes on the rock cycke depends upan the movements of the rock that
place the rock in the position to either crumble, be put under great pressure, or meltWhat is the
rock cycle?