Plate movement,
Erosion, and all
Earth Processes
give us…
Rocks!
Rocks!
• Made up of a mineral or a mixture of
minerals
• May also contain sediments and fossil
remains of plants and animals
• They are the result of natural forces at
work on our planet
• The study of rocks is called petrology
Rock made up of one type of
mineral
Quartzite – made up of the mineral quartz
The most common mineral on earth is quartz.
ROCKS are the records to our
planet’s past!
• They indicate where
rivers have flowed
• Where huge inland seas
were located
• What organisms lived in
those seas
• Where glaciers covered
land
Basic Rock Types
• All rocks fall into one of 3 basic groups:
1. Igneous
2. Sedimentary
3. Metamorphic
Igneous Rocks
Igneous means “fire”
Form from the cooling
of liquid rock
(magma) that came up
from deep within the
earth. It is the melting
and solidification of
metamorphic rocks!
Igneous rock is the most
common material of the
earth’s crust!
Igneous Rocks:
• Often hidden by sedimentary rock
• Can be intrusive or extrusive igneous rock
• If recrystallization and solidification
occurred below the earth’s surface (such
as the formation of granite), than the rock is
intrusive
• If the rock formed on the earth’s surface
from cooling of volcanic lava (such as
obsidian and basalt), than the rock is
extrusive
Igneous Rocks:
• If rock formed from a slow cooling, the rock will
contain coarse-textured minerals (Example =
granite)
• If rock formed from a fast cooling, the rock will
contain fine-textured minerals (Example =
basalt)
• If rock contains a high amount of silica, it will be
light in color and weight, and be known as
acidic
• If rock contains high amounts of iron and
magnesium, it will be dark-colored and heavy,
and be known as basic
Basalt
Most common extrusive and basic igneous rock
Granite
Most abundant of all igneous rocks
Sedimentary Rocks
• Form from the burial and cementing of
layers of sediment broken off of other rock
types and deposited in water. Weathering
and erosion can be caused by wind, waves,
gravity, or water. Rivers carry sediment
for long distances.
Sediment:
•
•
•
•
Sand
Gravel
Mud
Clay
Name of
Particle
Size Range
Loose
Sediment
Consolidated Rock
Boulder
>256 mm
Gravel
Cobble
64 – 256 mm
Gravel
Pebble
2 - 64 mm
Gravel
Sand
1/16 –2 mm
Sand
Sandstone
Silt
1/256 - 1/16
mm
Silt
Siltstone
Clay
<1/256 mm
Clay
Claystone, mudstone, and shale
Conglomerate or Breccia
(depends on rounding)
Compaction from the
weight of
accumulating sediment
results in layers that
become hardened and
turn to sedimentary
rocks!
Shale
Clastic
(clay)
Conglomerate
Clastic
(rounded pebbles)
Metamorphic Rocks
• Form from
pressure and
extreme
temperatures
changing the
chemistry of
igneous and
sedimentary
rocks that got
buried into the
earth over time.
Metamorphosis
• Complete change of character,
appearance, or condition.
• Involves heat, pressure, and chemical
action
• Process can occur more than once
• Results in the recrystallization of original
rock (sedimentary or igneous) and a
different mineral composition
Limestone metamorphosed to marble!
Shale metamorphosed to slate!
Rock Cycle
is a sequence of processes or events
involving the formation, alteration,
destruction, and reformation of rocks
The Importance of Rocks and Minerals
Name
Type of Rock
Use
Basalt
Igneous
Used in road building
materials
Calcite
Mineral
Used in cements and mortars and the production of
lime
Igneous
Used for buildings, monuments, and tombstones
Metamorphic
Used in building, floors, tile in bathrooms
Igneous
Used in making arrowheads and knives
Igneous
Used in scouring, scrubbing, and polishing materials
Quartz
Mineral
Used in making glass, electrical components, and
optical lenses
Sanstone
Sedimentary
Used in the building
industry for houses
Slate
Metamorphic
Used for roofs, chalkboards, and patio walks
Granite
Marble
Obsidian
Pumice
Landforms
• Part or area of the Earth’s surface that has a
distinctive shape or topography
Weathering
is a series of natural processes, both physical
and chemical, that act to change exposed rock
into mineral and rock particles and chemical
compounds in solution.