Por Carlos S. Melo (Universidade dos Açores / Instituto Dom Luiz).

Supratidal talus-platforms are low-relief subaerial accumulations of debris produced by mass wasting along high coastal cliffs, being particularly abundant at reefless volcanic islands. Known as “fajãs” across the Portuguese-speaking Atlantic archipelagos, these coastal morphologies on rare occasions may feature lagoons. Whilst the origin of fajãs is firmly established as being the product of coastal landslides, little is known about the processes that shape fajãs with lagoons. Our observations on the development of “Fajã dos Milagres” (Corvo Island) suggest that fajãs with lagoons may evolve through an evolutionary pattern with five main stages: 1) “islet stage”; 2) “gravel spit stage”; 3) “early lagoon stage”; 4) “mature lagoon stage”; and 5) “fajã (without lagoon) stage”. This study documented the generation and very fast subsequent evolution of a clastic coastal morphology solely driven by the varying action of waves and currents, and without interference from relative sea level and/or external sediment replenishment.

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