Meaning & use
sima
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Meaning
noununcountable
The heavy, dark rock rich in silicon and magnesium that makes up the ocean floors and lies under the continents.
Grammar: Uncountable: the sima lies beneath the sial; no plural is normally used.
Patterns
- the sima beneath something
- sima and sial
The ocean floor is made mostly of sima, which is denser than the rock of the continents.
Early geologists believed that continents of sial drifted over a layer of sima.
Basalt is a typical rock of the sima.
Common combinations
- layer of sima
- Beneath the thin sediments lies a layer of sima.
- sima and sial
- The textbook compared sima and sial in the Earth's crust.
- oceanic sima
- Oceanic sima is thinner than the continental crust above it.
- dense sima
- The dense sima sinks lower than the lighter continents.
Synonyms and how they differ
- oceanic crust
- Oceanic crust is the modern, preferred term for the same layer, while sima is an older name rarely used in current research.
Opposites
Word family
Commonly confused: sima or sial?
sima vs sial
Sial is the lighter rock rich in silicon and aluminum that forms the continents, while sima is the denser rock below and under the oceans.
Practice
Geologists once described the ocean floor as being made of dense ___, in contrast to the lighter sial of the continents.
Choose one answer.
Sima is the dense magnesium-rich rock that was contrasted with sial. Silt, slate, and shale are sedimentary or metamorphic rocks and are not named as crustal layers.
Make it your own
Write a sentence using “sima”, then check it and compare it with the examples above.