Download Notes: Rocks

Notes – Rocks ( Chp 6)
Rock- What is it?
Classified by how they form, texture & composition
a naturally formed solid made of a
a mixture of minerals or solid organic matter
3 families of rocks:
igneous,
Igneous RocksMost common in Earth’s crust
means "fire born". Forms from molten
material (magma, lava) within the earth that
cools, hardens & crystallizes
sedimentary, metamorphic
2 types: (based on texture)
b. Intrusive
formed inside the earth (magma). It usually has
large crystals ---cools slowly creating a coarse
texture (grainy)
ex. granite & gabbro
b. Extrusive
forms on the earths surface (lava). It usually
has small crystals - cools quickly creating a finegrained texture ex. basalt
c. Others
glass
vesicular
porphyritic
Sedimentary RocksMost common on Earth’s surface
Characteristics:
3 types:
a. Clastic
( most common)
-some cool so quickly, no crystals are formed
creating a glassy look
ex. obsidian
-cool quickly & have gas holes
ex. pumice
-cool at 2 speeds & have large & small crystals
Formed from weathering of rocks into
sediments that “cement” & harden together
creating visible layering of sediments
( bedding), cracks , ripple marks & fossils.
sediments that have been compacted &
cemented together.
ex. conglomerate, sandstone, shale
b. Chemical
water containing dissolved minerals evaporates
leaving mineral deposits behind.
ex. rock salt , gypsum, calcite
c. Organic
hardening & compression of dead plant &
animal remains (fossils , shells)
ex. limestone, coal, coquina
Metamorphic Rocks-
Formed from Igneous & Sedimentary rocks that
have been changed by heat, pressure or
chemicals deep under the ground.
( metamorphism)
Characteristics:
has coarse crystalline structure in parallel or
distorted colored bands that bend & fold .
Very dense.
2 types: ( texture)
a. Foliated
b. Nonfoliated
Rocks that change...
limestone (sed)
granite (ign)
shale (sed)
basalt (ign)
sandstone (sed)
slate (meta)
minerals are arranged in wavy alternating
bands due to recrystallization or flattening.
Has a sheet-like or flaky look
ex. gneiss , schist, slate
no bands or sheets----blocky looking. Looks to
contain 1 mineral type.
ex. marble, quartzite
...into metamorphic rock
marble
gneiss
slate
schist
quartzite
schist
ROCK CYCLE p. 126
Notes – Rocks ( Chp 6)
Rock- What is it?
Classified by how they form, texture & composition
3 families of rocks:
Igneous RocksMost common in Earth’s crust
2 types: (based on texture)
a. Intrusive
means "
". Forms from molten material
(magma, lava) within the earth that cools,
hardens & crystallizes
formed
has
the earth (magma). It usually
ex. granite & gabbro
b. Extrusive
forms
. It usually
ex. basalt
c. Others
Sedimentary RocksMost common on Earth’s surface
Characteristics:
3 types: (based on formation & composition)
a. Clastic
( most common)
-some cool so quickly,
creating a glassy look
ex.
-cool quickly &
ex.
-cool at 2 speeds & have large & small crystals
Formed from
into
sediments that “cement” & harden together
creating
( bedding), cracks , ripple marks &
ex. conglomerate, sandstone, shale
b. Chemical
water containing
leaving mineral deposits behind.
ex.
c. Organic
hardening & compression of
ex.
Metamorphic Rocks-
Formed from Igneous & Sedimentary rocks that
Characteristics:
has coarse crystalline structure in parallel or
distorted colored
2 types: ( based on texture)
a. Foliated
minerals are arranged in wavy alternating
bands due to
ex.
b. Nonfoliated
no bands or sheets----blocky looking.
ex.
Rocks that change...
limestone (sed)
granite (ign)
shale (sed)
basalt (ign)
sandstone (sed)
slate (meta)
Where did it start?
...into metamorphic rock
The Earth consisted entirely as magma, so it is
believed the first rocks to form were Igneous
Rocks.