atolls
type: Concept
definition: The term atoll is derived from the Maldivian word atholu and refers to a coral reef that forms a ring around a central lagoon. Above this coral rim are typically numerous small islets that are composed of coral sand, gravel, and aggregate. [Source: Encyclopedia of Geography; Atoll]
broader: geomorphology

geomorphology
type: Concept
narrower: atolls

concepts
type: Collection
type: ConceptGroup
member: atolls