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# stratum

noun (a stratum, strata)

«stratum» in the English dictionary: everyday — its meanings, how the lessons use it, and examples, each with its tree on Mova.

## Everyday

1. (science) A stratum is one layer of rock or soil lying on top of another. [tree →](https://mova.elamur.ai/free/en/corpora/dictionaries/school/S/stratum/#m1)
2. A stratum is a layer of anything, such as the air or the sea. [tree →](https://mova.elamur.ai/free/en/corpora/dictionaries/school/S/stratum/#m2)
3. (formal) A stratum is a level or class of people in a society. [tree →](https://mova.elamur.ai/free/en/corpora/dictionaries/school/S/stratum/#m3)

### In the lessons

In geography and science lessons strata are the layers you see in cliffs and canyons such as the Grand Canyon; lower strata are usually older, so they help scientists date fossils. In social studies it means a group at one level of wealth or power. Phrases: rock strata, social stratum, the upper strata.

### Examples

- Each stratum of rock in the cliff was a different colour. [tree →](https://mova.elamur.ai/free/en/corpora/dictionaries/school/S/stratum/#x1)
- The fossil was found in a stratum of limestone. [tree →](https://mova.elamur.ai/free/en/corpora/dictionaries/school/S/stratum/#x2)
- The Grand Canyon shows hundreds of strata. [tree →](https://mova.elamur.ai/free/en/corpora/dictionaries/school/S/stratum/#x3)
- The lowest stratum of rock is usually the oldest. [tree →](https://mova.elamur.ai/free/en/corpora/dictionaries/school/S/stratum/#x4)
- A thin stratum of ash came from an ancient volcano. [tree →](https://mova.elamur.ai/free/en/corpora/dictionaries/school/S/stratum/#x5)
- (formal) The book is about people from every stratum of society. [tree →](https://mova.elamur.ai/free/en/corpora/dictionaries/school/S/stratum/#x6)
- Clouds can form in a stratum of cold air. [tree →](https://mova.elamur.ai/free/en/corpora/dictionaries/school/S/stratum/#x7)

### Note

Plural strata (Latin), not «stratums». People often use «strata» as if it were singular; in careful writing say «one stratum, many strata». Related: stratosphere, stratus clouds.

## On Mova

- [Trees and pragmatics of «stratum» in the school dictionary](https://mova.elamur.ai/free/en/corpora/dictionaries/school/S/stratum/): every meaning and example parsed by Mova, with its dependency tree and frames.
- [«stratum» in the school dictionary](https://mova.elamur.ai/free/en/dictionaries/school/w/stratum.html) on Mova free.