2. Rocks
• A rock is an aggregate to
one or more minerals
which may or may not
contain glass, organic
matter, and mineraloids.
• Any solid mass of mineral
or mineral-like matter
occurring naturally as part
of our planet.
3. • Studying rocks would be
an essential part to
understanding the one of
the earth’s systems, the
geosphere.
• And because these rocks
are components that
revolve around the
system, understanding the
processes that transform
them from one form to
another will help us
understand more about
the planet as a whole.
6. Sedimentary rock is formed
from the weathered
of preexisting rocks that
been transported,
compacted, and cemented.
Sedimentary cliff strata, Zion Canyon, Utah
7. Metamorphic rock is formed
by the alteration of pre-
existing rock deep within
Earth (but still in the solid
state) by heat, pressure,
and/or chemically active
fluids.
8. The Rock Cycle
Shows the interrelationships
among the three rock types
(igneous, sedimentary, and
metamorphic)
9. • Magma is molten material that
forms deep beneath the Earth’s
surface.
• Lava is magma that reaches the
surface.
10. • Weathering is a process in
which rocks are broken
down by water, air, and
living things
• Sediment is weathered
pieces of Earth elements.
11. Energy
That
Drives
the Rock
Cycle
Processes driven by heat from the
Earth’s interior are responsible for
forming both igneous rock and
metamorphic rock.
Weathering and the movement of
weathered materials are external
processes powered by energy from
the sun.
External processes produce
sedimentary rocks.
12. Igneous Rocks: Rocks
formed by fire
• Magma is defined as
molten rock with associated
solid materials and gaseous
phases.
• Lava is simply a term to
describe magma that has
breached the surface.
13. The Source of Heat
The best way to generate magma is to heat a portion of
the solid earth.
1. Remnant heat from the formation of the earth is no
longer that high and readily available
2. Heat from radioactive decay of certain elements
• The earth is actually cooling from the sun (that’s
why we have solid crust)
• Going in ( and we still have molten materials inside
along with the trapped heat)
• We get a glimpse of such energy when we witness
volcanic eruptions which spews out molten material
we call lava (in areas we call hotspots)
14. Other Ways to Melt Rocks
• Decompression is the removal or decrease of a certain
pressure applied on a body.
• Given a rock that is undergoing pressure at certain
temperature, a decrease in pressure will allow a change in
phase once the ambient temperature is enough to do so at
the new prevalent pressure.
• Read the example on page 31.
15. Mid-oceanic Ridges
• The regions of the earth where new
oceanic material is extruded on the
surface.
• This extrusion of oceanic material causes
the expansion of oceanic crust which in
effect, extends the oceanic basin.
• Oceanic basins are regions on the surface
of the earth located below sea level.
16. 3 Major
Regions of the
Ocean Floor
1. Mid-oceanic Region
• Extensive stretch of
volcanic centers
forming new oceanic
crust.
17. 3 Major
Regions of the
Ocean Floor
2. Deep Ocean Margins
• Between continental
margins and oceanic
ridges, deep ocean
margins are found.
• Ocean margins are
defined by relatively
flat topography called
abyssal plains.
18. 3 Major
Regions of the
Ocean Floor
3. Continental Margins
Adjacent to continental land mases,
continental margins do not simply
start where shore lines the boundary.
Instead, continental margins grade
into continental shelf, slope, and rise.
a) Continental shelf is the gently
sloping platform from the
shore extending seaward
b) Continental slopes line the
boundary between continents
and deep ocean basins.
c) Continental rise marks areas
where trenches are absent
marking the end of continental
regime.
19.
20. Magma, Minerals, and
Igneous Rocks
• The fundamental material required to
produce igneous rock rocks would be
magma.
• Minerals are the primary components
of all rocks on earth.
• Majority of the minerals we see in
rocks can actually be grouped
together to form what we call
Common Rock-forming Minerals.
• The minerals that you will observe in
your igneous rocks will then be a
reflection of the composition of the
magma it came from.
22. • Rocks that formed on the
surface are called volcanic
rocks (from lava) while rocks
that cooled beneath the
surface are called plutonic
rocks.
• The distinction between
volcanic and plutonic rocks is
evident in textures.
26. Ultramafic: Peridotites and
Komatiites
• Igneous rocks composed of
mainly olivine and pyroxene
are called peridotites
(phaneritic) or komatiites
(aphanitic).
• Characterizes by the
abundance of ferromagnesian
minerals and are usually dark
green to black in color.
27. Mafic: Gabbro
& Basalt
• Majority of igneous rocks produced by
mid-oceanic ridges are within the
compositional group of gabbro and
basalts.
• Lower iron and magnesium content
compared with ultramafic
28. Intermediate: Diorite and
Andesite
• Minerals in transition
from mafic to felsic
• Its no longer
ultramafic nor mafic
but not yet achieving
felsic compositions
30. The Study of Igneous
Rocks
• The study of Igneous rocks is an
imperative window that permits
understanding of the processes
occurring deep within the earth
• Igneous rocks pioneer the other
two rocks types
• Ultimately, any rock will trace
back its lineage to an igneous
one.
