Download 9.2 Igneous and Sedimentary Rocks

Igneous and Sedimentary
Rocks
SWBAT explain how extrusive and
intrusive igneous rocks are different;
describe how different types of
sedimentary rocks are formed
What are the three types of rocks?
• Igneous
• Sedimentary
• Metamorphic
Igneous Rocks
• Igneous rocks
– form when melted rock material from inside
Earth cools.
• Extrusive
– igneous rocks that cool on Earth’s surface.
• Intrusive
– igneous rocks that cool under Earth’s surface.
Chemical Composition
• What determines the color of a rock?
– Color in rocks is determined by the chemical
materials in it.
• If a rock has a high percentage of silica
and little iron, magnesium, or calcium,
what color will it be and what is it called?
– It will be light in color
– It is called granitic
– They are generally intrusive rocks
Chemical Composition
• If a rock has a low percentage of silica and
contains more iron, magnesium, or
calcium, what color will it be and what do
we call it?
– It is darker in color
– It is called basaltic
– They are generally extrusive
Rocks from Lava
• Extrusive rocks
– have small crystals because of the quick
cooling time. They are formed from lava.
• Fissure
– A large crack in earth’s surface that magma
can come up through
Rocks from Magma
• Intrusive rocks
– have large crystals because of the extended
cooling time. They are formed from magma.
Sedimentary Rocks
• Sediments
– pieces of broken rock, shells, mineral grains,
and other materials.
• Sedimentary rocks
– when sediments collect in layers to form
rocks.
3 types of sedimentary rocks
• Detrital rocks
– made of grains of minerals or other rocks that
have moved and been deposited in layers by
water, wind, gravity, or ice.
– They are cemented together by minerals
dissolved in water.
– The weight of the layers above squeezes or
compacts them into rock.
3 types of sedimentary rocks
• Chemical rocks
– form when seawater, loaded with dissolved
materials, evaporates and layers of minerals
are left behind.
• Organic rocks
– form when living matter dies, piles up, and
then is compressed into rock