What Are Pillow Lavas and How Are They Formed?

What Are Pillow Lavas and How Are They Formed?

Most people are fascinated by the unique formations known as pillow lavas that can be found on the ocean floor. These geological structures are created when underwater volcanic eruptions occur, causing lava to rapidly cool and solidify in the cold waters. The rapid cooling process results in the formation of rounded shapes resembling pillows, hence the name. This phenomenon is not only visually striking but also plays a crucial role in plate tectonics and the formation of oceanic crust. By understanding how pillow lavas are formed, scientists gain insight into the complex processes that shape our planet’s geology.

Key Takeaways:

  • Pillow lavas are formed when lava erupts underwater.
  • The rapid cooling of lava in water causes it to solidify quickly, forming characteristic pillow-shaped structures.
  • Pillow lavas are commonly found along mid-ocean ridges and submarine volcanoes.

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The Formation of Pillow Lavas

Volcanic Activity Underwater

Underwater volcanic activity plays a crucial role in the formation of pillow lavas. When lava erupts underwater, the rapid cooling process causes it to solidify quickly, creating characteristic pillow-shaped structures. These formations are commonly found around mid-ocean ridges and submarine volcanoes. For more in-depth information on pillow lavas, refer to the Glossary – Pillow lava.

Cooling Process and Lava Solidification

Formation of pillow lavas occurs through the cooling process and lava solidification underwater. Another fascinating aspect is the interaction of hot lava with the cold ocean water, which causes it to cool rapidly and solidify into pillow-like structures. This rapid cooling process prevents the formation of large crystals and results in the characteristic rounded shapes of pillow lavas. This unique cooling process also helps to preserve the volcanic glass and mineral composition within the pillows.

Characteristics of Pillow Lavas

Morphological Features

Now, when it comes to the morphological features of pillow lavas, they have a distinctive pillow-like shape with rounded bulges and interconnected lobes. These formations are a result of the rapid cooling of lava when it comes into contact with water, usually in underwater volcanic eruptions.

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Textural Properties

On the other hand, the textural properties of pillow lavas are unique and reveal clues about their formation. They often exhibit a finely crystalline or glassy outer layer, with a more crystalline interior. This textural contrast is a result of the rapid cooling process underwater, which promotes the formation of glassy outer layers.

With further examination, scientists can also observe radial jointing within the pillow lavas, which are fractures that radiate from the center of the pillows outward. This distinctive feature is a result of the lava expanding as it cools and solidifies, creating these characteristic fractures.

Pillow lavas serve as remarkable geological formations that not only provide insights into past volcanic activities but also play a crucial role in understanding the processes that shape our planet’s surface. Their distinctive characteristics and formations make them a valuable area of study for geologists and volcanologists alike.

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Distribution and Occurrence

Common Locations and Environments

Many pillow lavas are found in underwater environments, particularly along mid-ocean ridges where volcanic activity is prevalent. These environments are characterized by high-pressure and low-temperature conditions, which are ideal for the formation of pillow lavas. Pillow lavas can also be observed in subglacial and subaerial settings, albeit less frequently compared to underwater environments.

Geological Implications and Contributions

Environments where pillow lavas are found provide crucial insights into the Earth’s geological processes. The unique shapes and textures of pillow lavas indicate the rapid cooling of lava upon contact with water, helping scientists understand the dynamics of underwater volcanic eruptions. Additionally, the presence of pillow lavas can indicate the past existence of ancient oceans or volcanic activity in certain regions.

More about Geological Implications and Contributions

Furthermore, the study of pillow lavas can aid in understanding the history of plate tectonics and the movement of tectonic plates. By analyzing the distribution of pillow lavas across different regions, geologists can piece together the puzzle of Earth’s geological evolution over millions of years.

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In terms of occurrence, pillow lavas are predominantly found along mid-ocean ridges, where they contribute to the formation of new oceanic crust. While pillow lavas are not typically associated with explosive eruptions, their presence can indicate ongoing volcanic activity and the potential for future undersea volcanic events.

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To wrap up

From above, pillow lavas are unique formations that result from the rapid cooling of lava erupting underwater. Their characteristic pillow-like shapes are created when the outer surface of the lava cools and solidifies quickly upon contact with the cold water, while the molten lava inside continues to flow and fill up the pillow structure. This process repeats, forming a stack of rounded structures resembling pillows. The formation of pillow lavas provides valuable insights into past volcanic activity and helps scientists better understand the geological processes at work beneath the Earth’s surface.


Q: What are pillow lavas?

A: Pillow lavas are a type of lava flow that forms underwater when basaltic lava erupts into a body of water, such as an ocean or lake. The lava cools rapidly in the water, causing it to form characteristic pillow-shaped structures.

Q: How are pillow lavas formed?

A: Pillow lavas are formed through a process called quenching, where the hot lava is rapidly cooled by the surrounding water. As the outer layer of the lava solidifies, it fractures, creating the pillow-like shapes that give pillow lavas their name.

Q: Where are pillow lavas commonly found?

A: Pillow lavas are commonly found along mid-ocean ridges, where tectonic plates spread apart and magma erupts onto the ocean floor. They can also be found in submarine volcanic arcs and other underwater volcanic settings where lava erupts into water.