About Rock and Volcano

1. ROCKS AND VOLCANOS
BY GROUP 3
1. DIFAHAR NILSA
2. NURHAYATI

2. OUTLINE
ROCKS
01
VOLCANOS
02
EARTHQUAKE
03

3. O1. ROCKS
A. THE DEFINITION OF ROCKS
B. THE TYPES OF ROCKS
C. THE ROCKS CYCLE

4. A. THE DEFINITION OF ROCKS
There are many definitions of rocks,
according to (Ehlers and Blatt, 1997). He defines
rocks as stuff which the earth is made off. A more
acceptable scientific definition of rocks is that; a
rock is a natural occurring solid cohesive
aggregate of one or more mineral or mineral
materials. Rocks are broadly classified into three
groups based on their process of formation.
Rocks on the Earth may be
composed of hundreds of possible
minerals but only 20 to 30 minerals are
common in the majority of rocks.
Minerals are made up of combinations of
nearly a hundred different elements, yet
only eight elements make up over 98% of
the Earth's crust.

5. 1. Igneous rocks 2. Sedimentary rocks 3. Metamorphic Rocks
Igneous rocks are formed
from solidification and
cooling of magma.
Sedimentary rocks are formed by the
accumulation and cementing of loose
sediment (eg., sandstone), the deposition
of chemical compounds held in solution in
water (eg., limestone), or by the
accumulation of animal or plant debris
(eg., coal).
Metamorphic rocks are formed under the
surface of the earth from the metamorphosis
(change) that occurs due to intense heat and
pressure (squeezing). The rocks that result
from these processes often have ribbon like
layers and may have shiny crystals, formed by
minerals growing slowly over time, on their
surface.
B. THE TYPES OF ROCKS
Generally rocks can be divided into three major types based on the process of their formation.
These are :

6. 1
Igneous rocks
Igneous rocks are divided into two main
c a t e g o r i e s :
Plutonic (intrusive) rock and volcanic (extrusive).
Igneous comes from word “ignis”
meaning fire, it is therefore not surprising that
igneous rocks are associated with volcanic
activity and their distribution is controlled by
plate tectonics.
Sometimes the magma cools inside the
earth, and other times it erupts onto the surface
from volcanoes (in this case, it is called lava).
When lava cools very quickly, either small or no
crystals form and the rock looks shiny and
glasslike. Sometimes gas bubbles are trapped in
the rock during the cooling process, leaving tiny
holes and spaces in the rock. Examples of this
rock type include basalt and obsidian.
Plutonic or intrusive
rocks result when
magma cools and
crystallizes slowly within
the Earth's crust. A
common example of this
type is granite.
Volcanic or extrusive
rocks result from magma
reaching the surface
either as lava or
fragmental ejecta,
forming rocks such as
pumice or basalt.

7. 2. Sedimentary rocks
THE
EXAMPLE OF
SEDIMENTAR
Y ROCKS
Sedimentary rocks may have a
coarse-grained, gravel-like
appearance or be extremely
fine grained, and may be hard
or soft. The principal varieties
are sandstone, limestone and
shale. Many sedimentary rocks
contain fossils and some, such
as coral reefs, are composed
entirely of such organic
remains.
Sedimentation is the
collective name for processes
that cause mineral and/or
organic particles (detritus) to
settle and accumulate or
minerals to precipitate from a
solution. Sediments can be
detrital, chemical or organic
sediments.

8. 3. Metamorphic Rocks
Metamorphic rocks are formed under the surface of the earth
from the metamorphosis (change) that occurs due to intense
heat and pressure (squeezing). The rocks that result from
these processes often have ribbon like layers and may have
shiny crystals, formed by minerals growing slowly over time,
on their surface.
Metamorphic rocks are basically rocks that have experience
change due to high pressure and temperature below zone of
diagenesis.
THE EXAMPLE OF
METHAMORPHIC ROCKS

9. C. ROCKS CYCLE
The Rock Cycle- any rock can become any type of
rock depending upon certain conditions. Igneous
rocks form when molten rock (magma and lava)
cools and harden. They break down by weathering
and the breakdown products are transported by
erosion.
The breakdown products are deposited to form
sedimentary rocks. Sedimentary rocks are buried,
subjected , pressure. Heat and pressure( without
melting) change rocks, forming metamorphic rocks.
Metamorphic rocks may eventually be heated
enough to melt, forming a new generation of
igneous rocks.
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10. Volcanoes

11. Volcanoes
Volcanoes in general can be defined as a system of hot fluid
channels (rocks in the form of liquid or lava) that extends from a
depth of about 10 km below the surface of the earth to the
surface of the earth, including sediments resulting from the
accumulation of material released when it erupts.

12. The Formation of Volcano
1. Expansion of the continental crust, the plates move away from each other so as to give
magma a chance to move to the surface and then form an arc of mid-ocean volcanoes.
2. Collision between crusts, where oceanic crust sinks beneath the continental crust. As a
result of friction between the crust occurs rock melting and melt rock is moving to the
surface through the fracture and then form a volcanic arc on the edge of the continent.
3. Continental crusts move apart from each other horizontally, giving rise to fractures or
fractures. The fracture or fracture becomes the path to the surface of molten rock or
magma to form a central volcanic arc or continental flooding along the fracture.
4. Depletion of oceanic crust due to plate movements provides an opportunity for magma to
break into the ocean floor, this breakthrough of magma is a flood of lava that forms a row
of shield volcanoes

13. Magma Extrusion Process
1. Linear Eruption
2. Central Eruption
3. Area extrusion
Area extrusion, occurs when the location of magma is close to
the surface of the earth, so that the magma melts out in several
places in a certain area.
Linear eruption or hemisphere eruption, is magma comes out
through cracks and crevices on the earth. Most of the magma
that comes out is liquid lava and contains very little loose
material. The nature of lava is usually basalt, forming a plateau
or basalt plateau.
Central Eruption, magma comes out through diatrema or crater.
Diatrema is a hole in the form of a pipe on a volcano that
connects the kitchen of magma with the crater or base of a
volcanic crater.

14. Volcano Based on It’s Shape
• Strato
Composed of eruption rocks with eruptive type that
changes so that it can produce layers in layers of several
types of rock, so that it forms a large (giant) cone,
sometimes in irregular shape, because the eruption has
occurred several hundred times. Mount Merapi is this
type.
• Shield
Composed of lava flow rocks which when deposited are
still liquid, so they do not have time to form a high cone
(steep), the shape will be sloping slope, and the
composition consists of basaltic rocks. Examples of the
shape of this volcano are in the Hawaiian islands.

15. • Cinder Cone
It is an ash volcano and small fragments of volcanic
rock spread around the mountain. Most of the
mountain of this type to form a bowl on top. Rarely
above 500 meters from the surrounding land.
• Caldera
This type of volcano is formed from a very strong
explosion that throws the top end of the mountain to
form a basin. Mount Bromo is this type.

16. Volcanoes Based on the Process of
Occurrence
• Maar Volcano
Shield / shield volcanoes, shaped like shields, occur because of
melt that comes out with low pressure, so that almost no
eruptions and form a very gentle slope with a slope of 1 to 10
degrees.
Maar volcano, shaped like a crater lake. Occurs because of a large
eruption which then forms a large hole in the peak. The materials
released are solid / effiata. For example, Mount Lamongan in East
Java.
Cone / srato volcano, which is the most common type of volcano.
Shaped like a cone with layers of lava and ash in layers. Occurs
because of the eruption and melting of hot and molten rock. The
frequent melt causes layers of mountain slopes to be called strato.
• Starto Volcano
• Shield Volcano

17. Types Of Volcanic Eruption
1. Hawaii Type
This type of volcano is on the Hawaiian Islands, in the middle of the Pacific
Ocean. Basaltic magma is very runny, so it is easy to flow a crater filled with
incandescent lava looks like a lava lake called Halemaumau.

18. 2. Stromboli Type
This type takes the name of the mountain stromboli found in the Mediterranean. orderly
and rhythmic nature Interspersed by strong eruptions or parasitism, namely the climax of a
volcanic eruption. The sprayed lava is basaltic and liquid, but different from the Hawaiian
type. Besides the smaller crater, this type of lavender is thinner and bursts containing a lot
of gas and throw ash and volcanic bombs.

19. 3. Vesuvian/Volcano Type
The lavas contain a lot of silica, closer to clogging the neck of the crater and causing
accumulation of gas pressure on the inside. This causes tremors before the eruption. The
eruption was as powerful as an atomic bomb explosion, throwing ash, lapilli and bombs
vertically far into the air. Because the lava are thick, the bombs don't spin so that when
they fall to the ground they will flatten, like pancakes.

20. 4. PeleanType
This type takes the name of the mountain stromboli found in the Mediterranean. orderly
and rhythmic nature Interspersed by strong eruptions or parasitism, namely the climax of a
volcanic eruption. The sprayed lava is basaltic and liquid, but different from the Hawaiian
type. Besides the smaller crater, this type of lavender is thinner and bursts containing a lot
of gas and throw ash and volcanic bombs.

21. gas pressure is low
gas pressure is
very high
gas pressure is
moderate

22. 5. Stromboli Type
This type of volcano eruption is very large in the form of a huge explosion accompanied by
a burst of ash and gas with a very large volume. Because of the magnitude of the eruption,
until it can cause the body of the mountain to be destroyed, as happened in Mount Bandai,
Mount Krakatau and Mount Katmai.

23. Earthquake
An earthquake is the result of a
sudden release of energy in the
Earth’s crust that creates seismic
wave. The seismic activity of an
area refers to the frequency, type
and size of earthquakes
experienced over a period of time

24. Terms Realted to Earthquake
Focus:
Focus is the point of the fault where
rupture occurs and the location from
which seismic waves are released
Epicenter:
The epicenter is the point on the
Earth’s surface that is directly above
the focus, the point where an
earthquake or underground explosion
originates

25. Fault Line:
A Fault line is the surface trace
of a fault, the line of
intersection between the fault
plane and the Earth’s surface
Fault Scarp:
A fault scarp is the topographic
expression of faulting attributed
to the displacement of the land
surface by movement along
faults

26. Causes of Earthquale
1. Runtuhnya Gua-gua di Dalam Bumi
Jika terjadi keruntuhan di dalam Bumi, hal itu hanya mungkin di daerah
pertambangan bawah tanah, penggalian batu kapur dan sejenisnya. Akan tetapi,
keruntuhan yang terjadi hanya dapat menimbulkan getaran bumi yang sangat kecil
dan bersifat lokal
2. Tabrakan Meteor
Gempa bumi dapat disebabkan oleh adanya meteor atau shooting star. Saat meteor
jatuh dapat menyebabkan terjadinya lubang yang sangat besar menyerupai kawah,
tetapi getaran yang dihasilkan akibat tabrakan meteor sangat kecil

27. 3. Volcanic Cause
Volcanic eruptions produce earthquakes. Earth quake may precede,
accompany and frequently follow volcanic eruptions. They caused
by sudden violent displacements of lava within or beneath the earth
crust
4. Tectonic Cause
Structural disturbance resulting in the relative displacements of the
parts of the lithosphere is the main cause of this type of earthquake.
Most of the disastrous earthquake belong to the category and occur
in areas of the great faults and fractures.

28. Thank You
ANY QUESTION?