Insights of long‐term geomorphological evolution of coastal landscapes in hot‐spot oceanic islands

• Published in: Earth surface processes and landforms 2019-02, Vol.44 (2), p.565-580
• Main Authors: Ferrer‐Valero, Nicolas, Hernández‐Calvento, Luis, Hernández‐Cordero, Antonio I.
• Format: Article
• Language: English
• Subjects: Abundance; Archipelagoes; Canary Islands; Cartographic databases; Coastal environments; Coastal evolution; Coastal geomorphology; coastal landforms; Coastal structures; Composition; Evolution; geodiversity; Geographic information systems; Geographical information systems; Geological time; Geology; Geomorphology; Hot spots (geology); Information systems; Islands; Landforms; Landscape; landscape evolution; Oceanic islands; Remote sensing; Satellite navigation systems; Sedimentary environments; Survival; Taxonomy
• ISSN: 0197-9337; 1096-9837
• DOI: 10.1002/esp.4518

The Canary Islands form a volcanic archipelago in which a west–east (W–E) chain of progressively older and less active islands can be observed. In the Canary Islands, unlike most hot‐spot archipelagos, certain geodynamic peculiarities have promoted longer periods of island survival, exceeding 20 Myr. This factor makes these islands a suitable context for this work, which aims to analyze extensively the coastal geomorphic structure on islands with different development states. For this, three islands in different volcanic phases were selected: La Palma (1.8 Myr), Gran Canaria (14.5 Myr) and Fuerteventura (22.6 Myr). An ad hoc landform‐based hierarchical taxonomy was designed to analyze the coastal geomorphic structure of the three islands. Based on a multi‐sourced analysis in geographic information system (GIS) and field recognition, a comprehensive cartographic database was collected using the coastline data‐storing (CDS) method as a feature abundance proxy. Three different aspects of the geomorphological structure were compared and related between the islands: (i) composition, (ii) abundance and (iii) diversity. Through their comparison, we attempt to explore geomorphological aspects of coastal evolution over geological spatiotemporal scales. Composition was explored analyzing the distribution of the feature's longshore frequencies (p). Abundance, by metrics of local abundance (N∩) and whole density (NU). Diversity, through four indices: normalized richness (S) and Margalef index (M) to estimate richness; Simpson index (D) and Shannon index (H’) to estimate evenness. We identified a systematic transformation in the dominant landform composition and a systematic trend in increasing geomorphological abundance and diversity from younger to older islands. The results show a long‐term structural pattern defined by the increase in coastal geomorphic complexity (abundance and diversity) over geological time, as the coasts evolve from predominantly rocky‐erosive to increasingly clastic‐depositional environments. This long‐term geomorphological pattern may be a general aspect of hot‐spot island archipelagos, which can bring a new perspective to the knowledge of their coastal evolution. © 2018 John Wiley & Sons, Ltd. The long‐term evolution of coastal geomorphic structure is examined by analyzing and comparing the geomorphological composition, abundance and diversity of the coasts of three hot‐spot islands in different stages of development. A pattern of change in