ROCK CYCLE
THINK ABOUT IT !
Why do you think
rocks don’t all look
the same ?
Why do you think
rocks are different ?
What do you think is
happening on Earth
that causes different
rocks to form ?
AGREE OR DISAGREE ?
• Once a rock forms as part of a mountain, it
does not change.
• Some rocks, when exposed on Earth’s surface,
undergo weathering and erosion.
WHAT IS A ROCK ?
A rock is a natural, solid mixture of minerals or grains.
HOW ARE ROCKS CLASSIFIED ?
• Geologists use a grain’s size, shape, and chemical
composition to classify rocks
– Texture: the size of minerals or grains in the rock and the
overall feel of the rock.
– Composition: can be used to determine where a rock
formed, such as inside a volcano or in a river.
3 TYPES OF ROCKS
•Igneous
•Sedimentary
•Metamorphic
ACTIVITY
•With a partner, brainstorm ways in which
rocks are involved in your daily life.
•After, create a list of rocks uses
IGNEOUS ROCK
• Magma or lava that has cooled and hardened
– EXtrusive Igneous Rock: EXits the crust of the Earth through a volcano
(lava)
– INtrusive Igneous Rock: Stays INside the Earth and cools slowly (magma
forms crystals)
IGNEOUS ROCK IDENTIFICATION
• Geologists determine whether an igneous rock is extrusive or
intrusive by studying the rock’s texture.
• If the crystals are small, the rock is extrusive.
• If all the crystals are large enough to see and have an interlocking
texture, the rock is intrusive.
SEDIMENTARY ROCK FORMATION
• Sedimentary Rock: rock that forms where sediments
are deposited
– Sediments : rock material that forms where rocks are broken
down into smaller pieces are dissolved by water
STEPS TO MAKE A SEDIMENTARY
ROCK
1. Rock breaks down into pieces
2. The pieces “erode” (travel) to a new
location (home) and become deposited
(dropped off)
3. Over time, water and force, cement and
compact the material to make a new rock
• Cementation- minerals and rock material
dissolve in rock and become stuck together
• Compaction: layers and layers of fluid get
squeezed out and forced together to make new
rock
METAMORPHIC ROCK
CLASSIFICATION
• Metamorphic Rock: rock is buried so
deeply into Earth’s crust that immense
HEAT and PRESSURE change the rock to
a new type of rock
• Metamorphic rocks are classified as:
– foliated: pressure squeezes the minerals
in a rock so they line up (rocks look
layered)
– non-foliated: minerals in the rock are
clumped together (rocks have bumpy
texture)