magma

Meanings

1. 1noununcountabletechnical

   Hot liquid or partly liquid rock that exists under the Earth's surface.

   Grammar: Uncountable: say 'magma', not 'a magma' or 'magmas' when talking about the substance.

   Patterns

   • magma rises
   • magma chamber
   • molten magma

   The volcano's magma chamber is slowly filling with molten rock.

   Scientists study how magma moves beneath the ocean floor.

   When magma reaches the surface, it is called lava.

2. 2noununcountabletechnical

   A mixture of molten or semi-molten material that can cool and harden into igneous rock.

   Grammar: Still uncountable; used in geology to talk about the material before it solidifies.

   Patterns

   • cooling magma
   • solidified magma
   • magma solidifies

   As the magma cooled, it formed crystals of granite.

   The rock was once magma that hardened deep underground.

   Heat from the magma altered the surrounding stone.

Common combinations

magma chamber

The magma chamber lies several kilometers below the volcano.

molten magma

Molten magma flowed into the cracks in the rock.

magma rises

Magma rises because it is less dense than the surrounding rock.

magma eruption

The magma eruption sent ash high into the sky.

Synonyms and how they differ

lava

Use 'lava' only after the molten rock reaches the surface; underground it is always magma.

molten rock

A general descriptive phrase; 'magma' is the precise geological term for the underground material.

Word family

magmatic adjective

Relating to magma, as in 'magmatic activity'.

Commonly confused: magma or lava?

Practice

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