The four types of volcanoes

Summary

This script explores the diverse world of volcanoes, distinguishing between Shield, Cinder Cone, and Stratovolcanoes, and introducing the lesser-known deep-sea volcanoes. It highlights the unique characteristics of these underwater formations, such as pillow lava, and invites viewers to ponder their classification, emphasizing the vastness of volcanic knowledge yet to be uncovered.

Takeaways

• 🌋 A volcano is a fissure in Earth's crust where magma moves towards the surface.
• 🛡️ Volcanoes are classified into three main types: Shield, Cinder Cone, and Stratovolcanoes.
• 🏔️ Shield volcanoes are broad, domed structures formed by layers of lava flows, like Mauna Loa in Hawaii.
• ⛰️ Cinder Cones are smaller and steeper, made of scoria from ejected lava bits that solidify in midair.
• 🗻 Stratovolcanoes are large, steep composite volcanoes with alternating layers of scoria and lava, like Mount Fuji in Japan.
• 🌊 Most volcanoes actually erupt underwater, creating a different kind of lava known as pillow lava.
• 🌍 There is a global ocean ridge system spanning over 70,000 kilometers, which is a nearly continuous range of underwater volcanic mountains.
• 🌐 The mid-Atlantic ridge is a famous example of a spreading ocean ridge, essentially one long underwater volcano.
• 🔥 Volcanic eruptions underwater are not explosive and create pillow lava, which is tube-shaped and indicative of submarine volcanic activity.
• 🧠 There is a lot more to learn about volcanoes, especially those hidden deep in the ocean.

Q & A

What is a volcano?

A volcano is a fissure in the Earth's crust that develops as magma moves forcefully towards the surface, often forming a structure as magma accumulates around the opening.

What are the three main types of volcanoes mentioned in the script?

The three main types of volcanoes mentioned are Shield volcanoes, Cinder Cones, and Stratovolcanoes.

Can you describe Shield volcanoes and give an example?

Shield volcanoes are large, broad, domed structures formed by layers of lava that flow quietly out of the vent and accumulate over time. An example is Mauna Loa in Hawaii.

What materials are Cinder Cones made of and how are they formed?

Cinder Cones are made of scoria, which are small bits of lava ejected by volcanic gases that harden in midair. They are steep because scoria is not thrown far from the vent.

Why are Stratovolcanoes considered the most beautiful type of volcano?

Stratovolcanoes are considered the most beautiful because they are large, steep, and composite volcanoes formed from alternating layers of scoria and lava, reaching great heights.

What is a deep-sea volcano and how does it differ from the three types mentioned?

Deep-sea volcanoes are those that erupt under the sea and cannot be easily classified as Shield, Cinder Cones, or Stratovolcanoes. They are part of the world's ocean ridge system and are different in formation and eruption style.

What is the mid-Atlantic ridge and how is it related to deep-sea volcanoes?

The mid-Atlantic ridge is a spreading ocean ridge and is considered one long underwater volcanic mountain range. It is related to deep-sea volcanoes as it is a site of volcanic activity that forms part of the Earth's tectonic plates.

What type of lava is typically formed during underwater volcanic eruptions?

Pillow lava is typically formed during underwater volcanic eruptions. It is distinctly tube-shaped and is indicative of a submarine volcanic eruption.

How does the volcanic process at mid-ocean ridges differ from traditional volcano types?

Volcanic processes at mid-ocean ridges differ as they are not explosive and generally create pillow lava, which is different from the lava formed in traditional volcano types.

What should we call submarine volcanoes according to the script?

The script suggests that we need to consider what to call submarine volcanoes since they do not fit into the traditional categories of Shield, Cinder Cone, or Stratovolcanoes.

What is the significance of the ocean ridge system in the context of volcanoes?

The ocean ridge system, spanning more than 70,000 kilometers, is significant as it represents a nearly continuous range of underwater volcanic mountains that are part of the Earth's tectonic activity.

Outlines

00:00

🌋 Volcanoes: Formation and Types

The paragraph introduces the concept of volcanoes as fissures in the Earth's crust through which magma forcefully moves towards the surface. It explains that volcanoes are formed by the accumulation of magma around these openings. The text categorizes volcanoes into three main types: Shield volcanoes, which are large and broad with gently sloping sides formed by layers of lava flows; Cinder Cones, which are smaller and steeper, made of scoria, a type of volcanic rock formed by solidified lava fragments ejected by volcanic gases; and Stratovolcanoes, which are large, steep, and composite volcanoes formed by alternating layers of scoria and lava. The paragraph also mentions that most volcanoes are found under the sea, and they do not fit into the three traditional types. These submarine volcanoes produce a different kind of lava known as pillow lava, which is indicative of underwater volcanic eruptions.

Keywords

💡Volcano

A volcano is a fissure or vent in the Earth's crust through which magma, ash, and gases are expelled. It is central to the video's theme as it sets the stage for discussing different types of volcanic structures and eruptions. The script mentions that volcanoes are formed as magma accumulates around these openings.

💡Magma

Magma is molten rock material found beneath the Earth's surface. It plays a crucial role in the formation of volcanoes, as it is the substance that moves towards the surface and creates volcanic structures. The script describes how volcanoes are formed as magma accumulates around fissure openings.

💡Shield Volcano

Shield volcanoes are characterized by their broad, low-profile shape, formed by the eruption of low-viscosity lava that flows a great distance before solidifying. Mauna Loa in Hawaii is given as an example in the script, illustrating how shield volcanoes are large and broad due to the quiet flow of lava.

💡Cinder Cone

Cinder cones are small volcanoes formed by the accumulation of scoria, which are small fragments of lava ejected by explosive eruptions. The script explains that these fragments do not travel far and thus create steep-sided cones, contrasting with the broad shield volcanoes.

💡Stratovolcano

Stratovolcanoes, also known as composite volcanoes, are tall, steep structures formed from alternating layers of lava, ash, and other volcanic materials. Fujiyama in Japan is highlighted as an example, showing how these volcanoes are both beautiful and formidable due to their height and strength.

💡Scoria

Scoria is a type of volcanic rock formed by the solidification of lava fragments ejected into the air during an eruption. It is mentioned in the context of cinder cones, emphasizing how these small bits of lava create the steep structure of these volcanoes.

💡Deep-sea Volcanoes

Deep-sea volcanoes are those that erupt under the ocean's surface. The script discusses how these volcanoes are different from the traditional types as they do not fit into the categories of shield, cinder cone, or stratovolcano and are part of the world's ocean ridge system.

💡Ocean Ridge System

The ocean ridge system refers to a continuous range of underwater volcanic mountains found at divergent margins. The mid-Atlantic ridge is noted as a prime example, illustrating the vast scale of these underwater volcanic formations.

💡Pillow Lava

Pillow lava is a type of lava formed during submarine volcanic eruptions, characterized by its distinctive tube-like shape. The script explains that these formations occur because underwater eruptions are not explosive, leading to the creation of this unique lava type.

💡Divergent Margins

Divergent margins are areas where the Earth's tectonic plates are moving apart from each other, creating spaces where new crust is formed, often through volcanic activity. The script mentions these margins in the context of the ocean ridge system, emphasizing their role in the formation of deep-sea volcanoes.

💡Mid-ocean Ridge

A mid-ocean ridge is a large underwater mountain system formed by plate tectonics, where new oceanic crust is created. The script describes the mid-Atlantic ridge as an example, noting its significance as a type of underwater volcano that does not fit traditional classifications.

Highlights

A volcano is defined as a fissure in the Earth's crust where magma moves forcefully towards the surface.

Volcanoes are classified into Shields, Cinder Cones, and Stratovolcanoes.

Shield volcanoes are large, broad, domed structures formed by layers of lava.

Mauna Loa in Hawaii is an example of a Shield volcano.

Cinder Cones are smaller volcanoes made of scoria, a volcanic rock.

Scoria is formed by bits of lava ejected by volcanic gases that harden in midair.

Stratovolcanoes are large, steep composite volcanoes formed from alternating layers of scoria and lava.

Fujiyama in Japan is a famous example of a Stratovolcano.

Most volcanoes erupt deep under the sea and are not easily classified into the three types.

Deep-sea volcanoes are part of the world's ocean ridge system spanning over 70,000 kilometers.

The mid-Atlantic ridge is a famous example of a spreading ocean ridge.

Submarine volcanic eruptions generally create a different kind of lava known as pillow lava.

Pillow lavas are distinctly tube-shaped and indicative of a submarine volcanic eruption.

Volcanic processes at mid-ocean ridges differ from traditional types of volcanoes.

Submarine volcanoes are an area of study with much to learn, especially those hidden deep in the ocean.

Transcripts

What do you think about when you think about volcanoes? Do you think about

explosive eruptions or slow lava flows? There is a lot more to know about

volcanoes and volcanic eruptions. First, let's talk about what a volcano is. A

volcano is defined as a fissure that develops in the Earth's crust as magma

moves forcefully towards the Earth's surface. Volcanoes are constructed as

magma accumulates around the fissure opening. Volcanoes are normally

classified into Shields, Cinder Cones and Stratovolcanoes. Shield volcanoes are

large, broad, domed structures formed by layers of lava that quietly flow out of

the vent and accumulate over time. Mauna Loa in Hawaii is a good example. A second

type is smaller and called a Cinder Cone. These are made of a volcanic rock called

scoria which are small bits of lava ejected by volcanic gases that hardened

in midair. Because scoria is never thrown very far

from the vent, cinder cones are steep. The most beautiful volcanoes are large, steep

stratovolcanoes. These are composite volcanoes that are formed out of

alternating layers of scoria, like pyroclastic material and lava. These

constructions are steep and strong and reach great heights.

Fujiyama in Japan is a famous example. These are the three types of volcanoes

that you may be familiar with, but did you know that most volcanoes erupt

deep under the sea? These deep-sea volcanoes can't easily be classified as

Shield, Cinder Cones, or Stratovolcanoes. So what are they? This is a map of the

world's ocean ridge system that spans more than 70,000 kilometers in total.

These spreading ridges are located at divergent margins and are defined as a

nearly continuous range of underwater volcanic mountains. The mid-atlantic

ridge is arguably the most famous example of a spreading ocean ridge. These

ridges are essentially one long volcano that is neither Shield, Composite, or

Cinder Cone. Because volcanic eruptions underwater are not explosive they

generally create a different kind of lava known as pillow lava. Pillow lavas

are distinctly tube shaped and are indicative of a submarine volcanic

eruption. The volcanic processes found at mid-ocean ridges

and the way that these volcanoes form are different than any of the three

traditional types of volcanoes. What do you think we should call these submarine

volcanoes? As you can see there is so much to learn about them especially

those hidden deep in the ocean.