The document outlines the objectives of studying volcanoes, including their formation, features, and types. It discusses geologic forces like diastrophism, erosion, and volcanism, detailing the processes that create different types of volcanoes such as cinder cones, composite, shield, volcanic domes, super volcanoes, submarine, and subglacial volcanoes. Additionally, it describes volcanic phenomena like geysers, fumaroles, and hot springs that indicate volcanic activity.

1. VOLCANOE
S
EXPLORING

2. Learning Objectives
At the end of the lesson, you should be able to:
1. Explain the formation of a volcano and
enumerate the different features of a volcano.
2. Describe the different types of volcanoes; and
3. Differentiate active volcanoes from inactive
volcanoes.

3. The study of the relief features of the
Earth`s crust is known as
Geomorphology.
The three primary geologic forces that
constantly alter the planet`s surface.
Diastrophism
Erosion
Volcanism

4. DIASTROPHISM
• Diastrophism is the vertical and horizontal
movement of the crust that results in
mountains. It is also distinguished by the large
movement of a portion of the Earth`s crust.

5. EROSION
• Erosion is the process where rocks are broken
down by natural forces such as wind or water.
There are two main types of erosion: chemical
and physical. Chemical erosion occurs when a
rock’s chemical composition changes, such as
when iron rusts or when limestone dissolves
due to carbonation. In physical erosion, the rock
breaks down but its chemical composition
remains the same.

7. WEATHERING
Weathering is the process by which rocks and other materials that
are exposed to the earth`s surface and come into contact with the
atmosphere decompose.
Weathering describes the breaking down or dissolving
of rocks and minerals on the surface of the Earth. Water,
ice, acids, salts, plants, animals, and changes in temperature are all
agents of weathering. Once a rock has been broken down, a process
called erosion transports the bits of rock and mineral away.

9. VULCANISM
• Volcanism is also known as vulcanicity. Refers
to variety of processes associated with the
surface discharge of magma or hot water and
steams, such as volcanoes, geysers, fumaroles
and hot springs.
• Vulcanicity covers all those processes in which
molten rock material or magma rise into the
crust or is poured out on its surface, there to
solidify as a crystalline or semi crystalline rock.

11. VOLCANOES
A volcano is an opening in a planet or moon's crust through which
molten rock and gases trapped under the surface erupt, often forming
a hill or mountain.
A volcano is an opening in the earth's crust through which lava,
volcanic ash, and gases escape. Volcanic eruptions are partly driven by
pressure from dissolved gas, much as escaping gases force the cork
out of a bottle of champagne.

12. GEYSER
A geyser is a rare kind of hot spring that is under pressure and
erupts, sending jets of water and steam into the air. Geysers are made
from a tube-like hole in the Earth's surface that runs deep into the
crust.

14. FUMAROLE
Fumarole is a geothermic vent that emits volcanic gases such as
carbon dioxide, nitrogen gas, carbon monoxide and hydrogen sulfide.
Fumaroles are vents or openings at the surface where volcanic gases
and vapors are emitted. Fumaroles are common features on active
volcanoes, and are an important sign that a volcano is active in that
fumaroles indicate the presence of heat from volcanic sources.

16. HOT SPRING
Hot spring also called a thermal spring is a source of geothermally
heated water rising to the surface of the Earth`s crust. It emerges
when precipitations or groundwater is heated by magma beneath the
Earth`s surface.

17. Formation of a Volcano
On land, volcanoes form when one tectonic plate moves under
another. Usually a thin, heavy oceanic plate subducts, or moves under,
a thicker continental plate. When this happens, the ocean plate sinks
into the mantle.
In the ocean, volcanoes erupt along cracks that are opened in the
ocean floor by the spreading of two plates called a mid-ocean ridge.
Volcanoes form here in two settings where either oceanic plate
descends below another oceanic plate or an oceanic plate descends
below a continental plate

19. TYPES OF VOLCANOES
Cinder Cones volcanoes are the smallest type of volcano. They are
rarely more than 1,000 feet tall. Cinder cone volcanoes often form on
the surface of larger volcanoes, creating a very active surface. They
usually do not erupt for very long.
Example: Smith Volcano, also known as Mount Babuyan, is a cinder
cone on Babuyan Island, the northernmost of the Babuyan group of
islands on Luzon Strait, north of the main island of Luzon in the
Philippines.

21. TYPES OF VOLCANOES
Composite Volcanoes also known as a stratovolcano are built up by
successive eruptions of domes, lava flows and pyroclastic flows, but
also can experience large blasts that destroy large areas of their
summits.
Example: Mayon volcano in Albay A volcano is a mound, hill or
mountain constructed by solid fragments, lava flows, and or dome-
like extrusions deposited around a vent from which the material is
extruded.

23. TYPES OF VOLCANOES
Shield Volcanoes are the largest volcanoes on Earth, they do not
form soaring mountains with conical peaks like composite volcanoes.
Instead, they are broad volcanoes with gentle slopes and are shaped
somewhat like a warrior’s shield lying flat on the Earth. Shield
volcanoes have a convex shape as they are flatter near the summit.
Example: Mt. Kanlaon is located in negros occidental a shield volcano
in the Philippines. A shield volcano means that the entire natural
structure resembles a shield when viewed from above the ground.
This type of volcano produces thin lava and can form mountains.

25. TYPES OF VOLCANOES
Volcanic Domes also called a lava dome. is a rounded, steep-sided
mound that is formed by small bulging masses of lava primarily
composed of either decite or rhyolite.
Example: Mt. Pinatubo is a dome complex and stratovolcano made of
dacite and andesite. This complex is surrounded by pyroclastic flow
and lahar deposits from large explosive eruptions. These explosive
eruptions have been clustered into 6-12 eruptive periods.

28. TYPES OF VOLCANOES
Super volcanoes described to produce the largest eruptions on Earth.
It is occur when magma in the mantle rises into the crust but the
magma can’t break through. Pressure builds in a large and growing
magma pool until the crust is unable to contain the pressure. This can
occur at hotspots or at subduction zones.
Example: The Yellowstone supervolcano, located in northwestern
Wyoming in Yellowstone National Park, is one of the largest volcanoes
in the world. It's erupted multiple times over the past 2.1 million
years, including three massive eruptions that smothered the
surrounding landscape in ash.

31. TYPES OF VOLCANOES
• Submarine Volcanoes is created when magma erupts in the
underwater fissures of the Earth. Also known as seamounts
(underwater mountains), submarine volcanoes can be just as
violent and in some cases larger than those on land. Submarine
volcanoes is shallow water can eject basaltic magma and the lava
formed is known as pillow lava.
Example: Didicas Volcano is an active volcanic island in the province
of Cagayan in northern Philippines.

34. TYPES OF VOLCANOES
• Subglacial Volcano also called glaciovolcano, is created by eruptions
beneath the surface of a glacier or sheets which are then melted into
lake by the rising lava that resembles the pillow lava formed by
submarine volcanoes. As the pillow lava is ejected upward, it melts
the overlying ice while the water cools the lava flows down.
• Example: Katla volcano is subglacial, basaltic-to–rhyolitic, and it has
the reputation of being one of the most dangerous volcanoes of
Iceland.