BharatNotes Atoll
noun (countable)Usage in a UPSC answer
The Lakshadweep archipelago, made up of 12 atolls, three reefs and five submerged banks, is low-lying and exposed to sea-level rise.
Synonyms
Antonyms
Word Family
atoll (noun), atollic (adjective, rare)
Root
Maldivian/Dhivehi atolu = administrative district of coral islands; no Latin root
Etymology
Borrowed into English via Portuguese atol from Maldivian Dhivehi atolu, meaning both a ring-shaped reef and a local administrative unit.
Memory Hook
An atoll forms a natural 'O' shape, like the letter in the middle of 'atoll', enclosing a calm lagoon. Imagine a doughnut (a-TOLL = a ring you pay toll at the gate of a lagoon).
How This Word Works in UPSC Writing
A ring-shaped coral reef enclosing a lagoon. Charles Darwin's subsidence theory explains the form through a three-stage sequence: a fringing reef forms around a volcanic island, becomes a barrier reef as the island subsides while coral growth keeps pace, and is left as an atoll when the island finally disappears beneath the surface. Lakshadweep provides the Indian example.
Don’t Confuse It With
An atoll is a ring reef enclosing a lagoon with no central island remaining. A fringing reef lies directly against the shore. A barrier reef is separated from the shore by a lagoon while the island is still present. A coral cay is a small sand island formed on a reef platform.
Hindi Meaning
प्रवाल वलय (pravāl valay) or एटोल, the loanword.
Common Questions
- What is an atoll?
- A ring-shaped coral reef enclosing a central lagoon, with no volcanic island remaining above the surface.
- How did Darwin explain atoll formation?
- Through subsidence: a fringing reef around a volcanic island becomes a barrier reef as the island sinks and coral grows upward, and becomes an atoll once the island is fully submerged.
Seen in UPSC Question Papers
- Prelims 2018 — Ecology
Real UPSC previous-year questions whose text uses “Atoll” — proof this word earns its place on your list.
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