ESS – Notes – Fall 2011
Name:
Hour:
Chapter 6: Rocks
The three major Rock types are:
Igneous Rock
Sedimentary Rock
Metamorphic Rock
Derived from a Latin term
meaning “From Fire”
Rocks, mineral crystals, and
organic matter broken into
fragments known as sediment
Metamorphic means
“Changed Form”
Igneous rock forms when
magma, or molten rock, cools
and hardens.
Magma is called lava when on
the Earth’s surface.
The Rock Cycle
Sediment is deposited and
compressed, then cemented
together, and hardened, to
form Sedimentary Rocks
Rock formed from existing
rock that is placed under
tremendous pressure and
extreme heat, and chemical
processes.
Answer the following questions using the diagram from the previous page.

How does metamorphic rock turn into sedimentary rock?
The metamorphic rock is weathered then goes through erosion forming sediment. The
sediment it then compacted and cemented forming sedimentary rock.

How does sedimentary rock turn into igneous rock?
Sedimentary rock undergoes massive heat and pressure forming metamorphic rock then melts
to form magma. When the magma cools it forms igneous rock.

How does igneous rock turn into metamorphic rock?
Igneous rock undergoes heat and pressure and the igneous rock is turned into metamorphic
rock.

How does sedimentary rock turn into a different sedimentary rock?
Sedimentary rock undergoes weathering and erosion forming sediment. The sediment is then
compacted and cemented forming a new sedimentary rock.
Properties of Rocks
ALL rocks have a distinct physical and chemical property that is determined by how the rock is
formed.
Igneous Rock
Most igneous rock can be identified as crystalline, or made of crystals. The chemical
composition of minerals in the rock and the rock’s texture determine the identity of the igneous
rock.


Magma: forms when rocks are put under extreme temperatures and pressures forming
magma.
Partial melting: When different minerals melt in igneous rocks leaving others unmelted.
Textures of Igneous Rocks:
Intrusive
Extrusive
Rock formed from SLOW cooling beneath
Earth’s surface.
Rock formed from FAST cooling on the Earth’s
surface.
COARSE GRAINED – The slow cooling allows
‘groups’ of minerals to clump together.
FINE GRAINED – The fast cooling does not
allow clumping of minerals.
Ex. Granite
Ex. Rhyolite
Composition of Igneous Rocks:
Felsic Rock
Mafic Rock
Light colored rock that forms because magma
contains a large proportion of silica.
Dark colored rock because of the iron based
minerals. Contain a small portion of silica.
Ex. Granite, rhyolite, and pumice.
Ex. Basalt and gabbro
Intrusive Igneous Rock Structures:
Igneous rock masses that form underground are called intrusions because they force their way
into, and in between, other rocks.
This happens when magma intrudes , or enters, into other rock masses and then cools deep
inside the Earth’s crust.
**** Will always be younger than the rock around them****
Batholiths:
Largest of all intrusions.
Spread over at least 100km2
Batholiths = “deep rock”
Stock:
Like Batholiths but are less than 100km2 and at the surface of the crust.
Laccoliths:
Magma flows between rock layers and forms a dome.
Laccolith = “lake of rock”
Sills:
Magma flows between rock layers and hardens. Like a window sill forms horizontally.
Dikes:
Magma forced through rock layers vertically.