Definition

Noun: * Pillow lava: A type of lava that has solidified into a mass of interconnected, rounded, pillow-shaped lobes. This distinctive structure is formed when lava erupts underwater or flows into a body of water, causing the outer surface to cool and solidify rapidly into a glassy crust while the interior continues to flow, creating the characteristic pillow shapes.

Usage Examples

• Noun:
  • Geologists identified the ancient rock formation as pillow lava, indicating a volcanic eruption on the sea floor millions of years ago.
  • The presence of pillow lava is a key piece of evidence that this area was once submerged under an ocean.

Advanced Usage

• "Pillow lava flows": This phrase describes the geological bodies or deposits formed by successive eruptions of pillow lava.
  • The submarine volcano produced extensive pillow lava flows along the mid-ocean ridge.
• "Pillow lava structures": Refers to the physical shapes and formations themselves.
  • The pillow lava structures were perfectly preserved in the cliff face.

Variants and Related Words

• Pillow basalt (n): A more specific term often used when the pillow lava has a basaltic composition, which is the most common type.
  • The canyon walls are composed of ancient pillow basalt.
• Hyaloclastite (n): A fragmental rock that often forms alongside pillow lava from the explosive interaction of lava and water.
  • The deposit consisted of pillow lava surrounded by brecciated hyaloclastite.

Synonyms

• Subaqueous lava: A broader term for lava that erupts or flows into water, which may or may not form pillow structures.

Related Concepts (Not Phrasal Verbs or Idioms)

• Mid-ocean ridge: A primary location where pillow lava is formed today.
• Submarine volcano: A volcano located under the ocean surface, a common source of pillow lava.
• Pillow joint: The cracks or spaces between individual pillow lobes.

Noun

1. lava that hardened in rounded shapes suggestive of pillows; believed to result from underwater eruptions