Island types, origins, and dynamics

Abstract ‘Island types, origins, and dynamics’ focuses on how islands emerge and develop as platforms for life. It introduces the classic subdivision into oceanic islands, continental fragments, and continental shelf islands and reviews more recent geological subdivisions of categories of oceanic island. It highlights distinctions between island geodynamics linked to divergent, convergent, and transverse plate boundaries, and those associated with various intraplate settings. These dynamics are also shown to be linked to biogeographical debates about disjunct distributions. A general ontogeny is described for islands of hotspot origin involving steep, high, active volcanos, giving way to more complex and dissected terrain, followed by decline as islands erode and/or subside. The processes of island origin, development, and eventual disappearance are illustrated with specific reference to Macaronesia (including the Canary Islands), Hawaii, and the Caribbean. The characteristics and origins of coralline islands, reefs, atolls, and guyots are also described.