Lava flow

Definition

A lava flow is a stream of molten rock that erupts from a volcano and moves across the Earth's surface. The characteristics of lava flows, including their viscosity and temperature, are largely determined by the composition of the magma from which they originate. Understanding these flows is essential for grasping how different types of volcanoes behave during eruptions and the resulting landforms they create.

5 Must Know Facts For Your Next Test

1. Lava flows can vary in speed, with some moving rapidly down slopes while others creep slowly across the landscape.
2. The temperature of lava flows typically ranges between 700°C to 1200°C (about 1300°F to 2200°F), affecting their fluidity and behavior.
3. Different types of lava flows include 'aa' and 'pahoehoe', which have distinct textures and movement patterns due to their varying compositions.
4. Lava flows can create new landforms, such as lava plateaus and volcanic islands, reshaping the landscape over time.
5. The cooling process of lava flows can lead to the formation of unique geological features like columnar jointing or pillow lavas underwater.

Review Questions

• How does the composition of magma influence the characteristics of a lava flow?
  • The composition of magma significantly impacts the characteristics of a lava flow by affecting its viscosity, temperature, and gas content. For example, basaltic magma is low in viscosity, allowing it to flow easily and create broad, smooth lava flows. In contrast, more viscous magma, such as rhyolitic magma, leads to slower-moving lava that tends to pile up near the vent, creating steep-sided lava domes instead of extensive flows.
• Compare and contrast the eruption styles associated with different types of volcanoes in relation to their lava flows.
  • Different types of volcanoes exhibit distinct eruption styles that are influenced by their lava flows. Shield volcanoes, composed primarily of low-viscosity basaltic lava, typically produce gentle eruptions that result in widespread lava flows. In contrast, stratovolcanoes often erupt more explosively due to their thicker magma, leading to pyroclastic flows and ash rather than extensive lava flows. This variation in eruption styles affects not only how a volcano shapes the landscape but also poses different hazards to nearby communities.
• Evaluate the impact of lava flows on volcanic landforms and ecosystems over time.
  • Lava flows have a profound impact on volcanic landforms and ecosystems as they reshape landscapes and alter habitats. Over time, as lava cools and solidifies, it forms new geological features like lava tubes or plateaus. These transformations can create opportunities for new ecosystems to develop; however, they can also destroy existing habitats. The subsequent weathering of cooled lava contributes nutrients to soil formation, allowing vegetation to establish itself over time. Understanding these processes is crucial for appreciating the dynamic interplay between volcanic activity and ecological succession.

Related terms

Magma: Magma is molten rock found beneath the Earth's surface, which can solidify to form igneous rocks or erupt as lava.

Volcanic eruption: A volcanic eruption is the release of gas, ash, and lava from a volcano, which can vary in style based on the magma's composition and pressure.

Pahoehoe: Pahoehoe is a type of lava flow characterized by its smooth, ropy surface, typically associated with low-viscosity basaltic lava.