Once a rock is formed, does it
stay the same rock forever?
The Rock Cycle
• Rocks changing from one type to one
of the other 2 types.
• “Ignis” = Latin for “fire”
• Formed from the cooling of either
magma or lava
• The most abundant type of rock
• Formed from sediments
mineral grains, animal
& plant remains) that
are pressed or
• These sediments are moved by wind, water,
ice or gravity.
• Sedimentary rocks cover 70% of the
• Water can easily erode
• Sedimentary rocks are fossil-carrying
How can sedimentary rocks help us
understand the age of fossils?
• As sedimentary rocks
are made, they form
• The layers on top
(and the fossils in
the top layer) are
YOUNGER than the
fossils in lower
• Rocks that have changed due to
intense temperature and pressure
• “Meta” means “change” and “morph”
means “form” in Greek
• Igneous, sedimentary and other
metamorphic rocks can change to
become metamorphic rocks
What occurs in the Earth to
change these rocks?
• Pressure from overlying rock layers
• High heat, but not enough to melt the rock
Review of how the 3 rock types are formed….
1. What are the three types of rocks?
2. What type of rocks hold fossils?
3. What kind of rock has the Grand Canyon formed
in (take your best guess)?
4. What kind of rock is made from lava?
5. What is the most common rock we see on the
6. Will an igneous rock stay an igneous rock