Earth materials, internel structure of the earth, composition of the earth
1. EARTH MATERIALS
1. Internal Structure of the Earth
2. The Processes that Change the Shape of the
3. Composition of the Earth
4. Basic Rocks Types
5. Common Rock Forming Minerals
2. The earth is composed of three basic spheres: the core, the mantle, and
The crust is the layer that is of most importance in geology. Geologists
distinguish between oceanic crust and continental crust. Oceanic crust
lies under the oceans and is thin about 6-10 km and is made up
primarily of heavy rock that is formed when molten rock (magma)
cools. Continental crust is thick about 20-70 km and is composed of
rock that is relatively light as compared to oceanic crust.
The crust is continuously changing and moving because of two major
forces of nature—
PlateTectonics/Orogeny and weathering/erosion.
Orogeny, or mountain building, is a process in which the layers
of the crust are folded and pushed upward by such processes as plate
tectonics and volcanism.
Weathering and erosion are the opposing forces in which the
sediments are broken down and transported.
Internal Structure of the Earth
3. The Divisions of
Size of the Earth
Radius = 6370 km
Diameter = 12,740
5. The whole earth is made of rocks & minerals.
Inside the earth there is a liquid core of molten rock and on the outside there is a hard
crust of solid rocks. If you compare the earth to an egg, the shell on an egg is like the
crust on the earth.
The crust is made up of rocks and minerals.
Much of the crust is covered by water, sand, soil and ice.
If you dig deep enough, you will always hit rocks. Below the loose layer of soil, sand &
crumbled rocks found on Earth is bedrock, which is a solid rock.
•The Crust makes up less than 1% of the Earth’s mass (0.4%)
It is made of oxygen, silicon, aluminum, iron, calcium, sodium, potassium and
These 8 elements make up 99% of the Earth’s crust.
•The continents are about 35 km thick and the ocean floors are about 7 km thick.
•The Mantle is the solid casing of the Earth and is about 2900 km thick.
It makes up about 70% of the Earth’s mass (68.1%).
It is made up of silicon, oxygen, aluminum and iron.
•The Core is mainly made of iron and nickel and makes up about 30% of the Earth’s
The Outer Core is 2200 km thick and is liquid and the Inner core is 1270 km thick and is
Composition of the Earth
6. Component Symbol Volume
Oxygen O 46.6%
Silicon Si 27.8%
Aluminum Al 8.1%
Iron Fe 5.0%
Calcium Ca 3.6%
Sodium Na 2.8%
Potassium K 2.6%
Magnesium Mg 2.0%
Elemental abundances in the crust (% wt ).
7. Elemental abundances in the crust (% wt ).
0 SI Al Fe Ca Na K Mg Oth
46.6 27.7 8.1 5.0 3.6 2.8 2.6 2.0 1.6
10. • Rocks are all around us. They make up the backbones of hills and
mountains and the foundations of plains and valleys. Beneath the
soil you walk on and the deep layers of soft mud that cover the
ocean basins is a basement of hard rock.
• Rocks can be defined as the unit of the earth’s crust or as an
aggregate of minerals.
• Rocks are made up mostly of crystals of different kinds of minerals,
or broken pieces of crystals, or broken pieces of rocks. Some rocks
are made of the shells of once-living animals, or of compressed
pieces of plants.
• Rocks are divided into three basic types, igneous, sedimentary and
metamorphic, depending upon how they were formed. Plate
tectonics provides an explanation for how rocks are recycled from
igneous to sedimentary to metamorphic and back to igneous again.
ROCKS & MINERALS
11. Weathering is the process of physical disintegration and chemical
changes in the composition of earth materials (Rocks and Minerals).
There are two types of weathering:
Physical— occurs when solid rock is fragmented by physical
processes that do not change the rock’s chemical composition. These
processes include wind (aeolian forces), water (freezing, flowing, wave
action, etc), heat, and even glacial movement.
Frost wedging is one example of physical weathering.
Chemical— occurs when minerals in a rock are chemically
altered or dissolved. The weathering of potassium feldspar to form
kaolinite, a clay, is an example of chemical weathering.
Weathering and erosion are closely interrelated geological
processes. As a rock weathers, it becomes susceptible to erosion.
Erosion is the removal of weathered debris.
These and additional forces and processes have resulted in the creation
of subsurface geological formations in which petroleum reservoirs are
WEATHERING & EROSION
Igneous rocks are formed by cooling and solidification of magma
Sedimentary rocks are formed by consolidation and cementation of
the sediment deposited under water
Metamorphic rocks are formed when the pre existing rocks have
been changed in texture, structure and composition by increase in
temperature and pressure
Igneous Sedimentary Metamorphic
14. The earth’s crust is composed of three basic rock types: igneous, sedimentary and
Igneous rocks are formed from the crystallization of molten rock (magma or lava)
from within the earth’s mantle. Common igneous rocks include granite, syenite,
basalt, and gabbro.
Metamorphic rocks are formed from pre-existing rocks by mineralogical, chemical
and/or structural changes in response to marked changes in temperature, pressure,
shearing stress, and chemical environment. These changes generally take place deep
within the earth’s crust. Examples of common metamorphic rocks include slate,
marble and schist.
Sedimentary rocks are formed as sediments, either from eroded fragments of
older rocks or chemical precipitates lithify by both compaction, as the grains are
squeezed together into a denser mass than the original, and by cementation, as
minerals precipitate around the grains after deposition and bind the particles
together. Sediments are compacted and cemented after burial under additional
layers of sediment. Thus sandstone forms by the lithification of sand particles and
limestone by the lithification of shells and other particles of calcium carbonate. These
types of rocks are typically deposited in horizontal layers, or strata, at the bottom of
rivers, oceans, and deltas.
Limestone, sandstone, and clay are typical sedimentary rocks.
15. Igneous rocks (from the Greek word for fire) form from the crystallization and solidification
of hot, molten rock (magma) materials. The melt originates deep within the Earth near
active plate boundaries or hot spots, then rises toward the surface. Igneous rocks are
divided into two groups, intrusive or extrusive, depending upon where the molten rock
solidifies on or near the surface or deep seated into the subsurface .
Extrusive igneous rock
Extrusive , or volcanic, igneous rock is produced
when magma exits and cools outside of, or very
near the Earth’s surface. These are the rocks that
form at erupting volcanoes and oozing fissures.
The magma, called lava when molten rock
erupts on the surface, cools and solidifies almost
instantly when it is exposed to the relatively cool
temperature of the atmosphere.
Quick cooling means that mineral crystals don't
have much time to grow, so these rocks have a
very fine-grained or even glassy texture. Hot gas
bubbles are often trapped in the quenched lava,
forming a bubbly, vesicular texture. Pumice,
obsidian, and basalt are all extrusive igneous
16. Intrusive igneous rock
Intrusive, or plutonic igneous rock
forms when magma is trapped deep
inside the Earth. Great globs of
molten rock rise toward the surface.
Some of the magma may feed
volcanoes on the Earth’s surface, but
most remains trapped below, where
it cools very slowly over many
thousands or millions of years until it
solidifies. Slow cooling means the
individual mineral grains have a very
long time to grow, so they grow to a
relatively large size. Intrusive rocks
have a coarse grained texture. The
image at right shows granite, an
intrusive igneous rock.
Intrusive igneous rock
17. Metamorphic rocks are formed from pre-existing rocks by
mineralogical, chemical and/or structural changes in response to
marked changes in temperature, pressure, shearing stress, and
chemical environment. These changes generally take place deep
within the earth’s crust. Examples of common metamorphic
rocks include slate, marble and schist.
18. Sedimentary rocks are formed from pre-
existing rocks or pieces of once-living
organisms. They form from deposits that
accumulate on the Earth’s surface.
Sedimentary rocks often have distinctive
layering or bedding. Many of the
picturesque views of the desert
southwest show arches made of layered
Clastic sedimentary rock
Clastic sedimentary rocks are the group of
rocks most people think of when they
think of sedimentary rocks. Clastic
sedimentary rocks are made up of pieces
(clasts) of pre-existing rocks. Pieces of
rock are loosened by weathering, then
transported to some basin or depression
where sediment is trapped. If the
sediment is buried deeply, it becomes
compacted and cemented, forming
Clastic sedimentary rock-
19. Biologic sedimentary rock
Biologic sedimentary rocks form
when large numbers of living things
die, pile up, and are compressed and
cemented to form rock.
Accumulated carbon-rich plant
material may form coal. Deposits
made mostly of animal shells may
form limestone, coquina, or chert.
Biologic sedimentary rock
Chemical sedimentary rock
Chemical sedimentary rocks are formed by chemical precipitation. The
stalactites and stalagmites you see in caves form this way, so does the
rock salt that table salt comes from. This process begins when water
traveling through rock dissolves some of the minerals, carrying them
away from their source. Eventually these minerals can be redeposited, or
precipitated, when the water evaporates away or when the water
becomes over- saturated with minerals.
21. Sedimentary rocks are the most important and
interesting type of rock to the petroleum industry
because most oil and gas accumulations occur in them;
igneous and metamorphic rocks rarely contain oil and
All petroleum source rocks are sedimentary
Furthermore, most of the world’s oil lies in sedimentary
rock formed from marine sediments deposited on the
edges of continents. For example, there are many large
deposits that lie along the Gulf of Mexico and the Persian
22. The Rock Cycle
Igneous, metamorphic, and sedimentary rocks are related
by the rock cycle, the circular process by which each is
formed from the others.
Rocks are weathered to form sediment, which is then
During deeper and deeper burial, the rocks undergo
metamorphism and/or melting.
Later, they are deformed and uplifted into mountain chains,
only to be weathered again and recycled.
The Rock Cycle
23. The rock
The Rock CycleThe Rock Cycle
and sedimentary rocks
are related by the rock
cycle, the circular
process by which each
is formed from the
Rocks are weathered to
form sediment, which is
During deeper and
deeper burial, the rocks
Later, they are
deformed and uplifted
into mountain chains,
Mineral can be defined as a naturally occurring inorganic solid
substance having a definite atomic structure and a certain range of
chemical composition. This image shows some of the most common
minerals you'll find in rocks.This pile contains plagioclase feldspar,
pyroene and calcite.
20minerals are most
common and is
found in the
composition of most
of the rocks.
25. COMMON ROCK FORMING MINERALS
Plagioclase is a member of the
feldspar mineral family. Plagioclase
feldspars are yet another silicate that
contains considerable sodium or
calcium. Feldspar crystals are stubby
prisms, generally white to gray and a
glassy luster. This variety of
plagioclase, called albite, is rich in
Quartz is one of the most common
minerals in the Earth’s crust. It is
made up of silicon dioxide (SiO2),
otherwise known as silica.
26. COMMON ROCK FORMING MINERALS
Potassium feldspar is another member of the
feldspar mineral family. Like plagioclase
feldspar, potassium feldspars are silicate
minerals that contain a considerable amount
of potassium. Feldspar crystals are stubby
prisms, often pink to white. Some potassium
feldspars, such as the one shown to the left
have a streaky appearance called perthitic
Micas are another group of silicate minerals
composed of varying amounts of potassium,
magnesium, iron as well as aluminum, silicon
and water. All micas form flat, book-like
crystals that peal apart into individual sheets
on cleavage planes. Crystals cleave into
smooth flakes. Biotite is dark, black or brown
mica; muscovite, shown here, is light-colored
or clear mica. Mica is so soft that you can
scratch it with a fingernail.
The amphiboles are a family of silicate
minerals that form prism or needle-like
crystals. Amphibole minerals generally
contain iron, magnesium, calcium and
aluminum in varying amounts along with
silicon, oxygen, and water. Hornblende,
shown in this image, is a common dark green
to black variety of amphibole; it is a
component in many igneous and
COMMON ROCK FORMING MINERALS
Olivine is another silicate mineral containing
iron and magnesium. It is a green, glassy
mineral that forms at high temperature. It is
common in basalt and in ultramafic rocks.
Gem-quality olivine is called peridote. A
rock made up entirely of olivine is called
Calcite is made of calcium
carbonate (CaCO3). Generally
white to clear, it is easily
scratched with knife. Most
seashells are made of calcite or
related minerals. This is the 'lime'
COMMON ROCK FORMING