ROCK CYCLE
Glue this side
into your
Science Journal
There are 3 general classes of rocks: Igneous,
Sedimentary, and Metamorphic. Rocks are classified
by how they formed and what they’re made of.
Geologists classify rocks by observing color, texture and
mineral composition. These observations help identify what
type of rock it is.
• Texture: the size, shape, and pattern of the rock’s
grain.
• Color: the apparent color of the rock, on the inside
and the outside.
• Mineral composition: The minerals that make up the
different parts of a rock.
Metamorphic rocks are formed from Igneous and
Sedimentary rocks under extreme:
• Heat
• Pressure
FOSSILS
Fossils…are any remains or imprints of living things of the
past. Fossils are found in sedimentary rocks.
Importance of Fossils
 Fossils provide information about life and conditions
in the past.
 Plant fossils can tell us about the ancient environment.
 Animal fossils can tell us about past environments,
what the animal ate, and how they lived.
 Scientists study them to learn about extinct plants and
animals.
IGNEOUS ROCKS
Igneous Rocks… are formed when lava and magma
crystallize to form solid rock. Igneous means “born of fire”
Sedimentary Transformations
Point A: Water or wind deposits sediments (Deposition)
Point B: The heavy sediments press down on the layers
beneath (Compaction)
Point C: Dissolved minerals flow between the particles
and cement them together (Cementation)
METAMORPHIC ROCKS
Metamorphic Rocks…are formed when an existing rock is
partially melted, squeezed, or both. Metamorphic rocks
were once igneous or sedimentary rocks that have
"morphed" into another kind of rock because of heat and
pressure.
How do sedimentary and igneous rocks change?
If you exam metamorphic rock samples closely, you'll
discover how flattened some of the grains in the rock are.
Magma vs. Lava
• Magma is a hot liquid made of melted minerals.
• When magma pours onto the earth’s surface it is
called lava.
• The longer it takes for the magma or lava to cool, the
more time mineral crystals have to grow. The more
time the crystals have to grow the coarser the texture
of the resulting igneous rock.
• Igneous rock can form underground, where the
magma cools slowly. Or, igneous rock can form
above ground, where the magma cools quickly.
3 Ways a Rock Can Melt
 Temperature – An increase in temperature deep
within the Earth’s crust can cause the minerals in a
rock to melt.
 Pressure – The high pressure deep within the Earth
forces minerals melt from intense heat and pressure.
 Composition – Fluids like water and carbon dioxide
enter a rock that is close to its melting point. When
these fluids combine with the rock, they can lower the
melting point of the rock enough for it to melt and
form magma.
2 Types of Igneous Rocks
• INTRUSIVE IGNEOUS ROCKS – When igneous
rocks are formed by magma that cools BENEATH
Earth’s surface.
• EXTUSIVE IGNEOUS ROCKS – When igneous
rocks are formed by LAVA ON Earth’s surface.
SEDIMENTARY ROCKS
Sedimentary Rocks…are formed when sediments (sand
clay, and silt) are compressed and become solid rock
4 ways Sedimentary Rock can be formed?
• Erosion
• Deposition
• Compaction
• Cementation
Lithification…The process by which sediment becomes
sedimentary rock
• 1st step : Erosion
• 2nd step : Deposition
• 3rd step : Compaction
• 4th step : Cementation
Sedimentary Rocks - Erosion...Destructive forces breaking
up and wearing away all the rocks on Earth’s surface by heat
and cold, rain, waves, and grinding ice. Erosion occurs
when running water or wind loosens and carry away the
fragments of rock.
Sedimentary Rocks – Deposition…The process by which
sediment settles out of the water or wind carrying it.
• Moving water or wind slows and deposits the
sediment.
• Sediment may include shells, bones, leaves, stems,
and other remains of living things.
• Remains of living things in the sediment may slowly
harden and change into fossils trapped in the rock.
Sedimentary Rocks – Compaction…New sediments fit
together loosely, but gradually, thick layers of sediment
build up creating new layers.
• Layers are heavy and press down on the layers
beneath them.
• Compaction is the process that presses sediments
together.
• Weight of the layers compacts the sediments,
squeezing them tightly together.
• The layers often remain visible in the sedimentary
rock.
Sedimentary Rocks – Cementation…The process in which
dissolved minerals crystallize and glue particles of sediment
together.
• While compaction is taking place, the minerals in the
rock slowly dissolve in the water.
• The dissolved minerals seep into the spaces between
particles of sediment.
• It takes millions of years for compaction and
cementation to transform loose sediments into solid
sedimentary rock.