All Islands and Archipelagos (filed here)

This group collects members of the Structural and Tectonic Formations subcategory that are islands or island groups rather than mainland structural features: continental fragments, volcanic island chains, and archipelagos whose formation is tectonic in origin but whose geography is an island rather than a landmass feature. The report behind this atlas's group-level work flagged a genuine mixing of island and archipelago entries into this subcategory alongside true tectonic formations; this group keeps that mixing honest and visible rather than hiding it, without moving the underlying entities to a different subcategory, which is a separate content decision outside a group-level pass.