A MULTIPHASE MODEL FOR THE FORMATION OF ENIGMATIC COASTAL GEOMORPHIC FEATURES OF NW CURAÇAO; A CASE STUDY OF BOKAS FROM SHETE BOKA NATIONAL PARK

Shete Boka National Park, Curaçao is named after the presence of a series of at least seven narrow inlets cut into the limestone terraces of the rugged North coast. These bokas or “mouths” are connected to ephemeral streams (arroyos) that have eroded into the siliciclastic bedrock inland of the coastal limestone terraces. The arroyos rarely contain running water except on occasion during the rainy season – which lasts from October to December. The origin of these geomorphic features has not been well substantiated in the literature. The presence of the bokas is enigmatic because: 1) there are multiple sets along the North coast, 2) they demonstrate similar morphologies and structural trends, 3) there are multiple processes contributing to the development of the coastline, and 4) presently stream runoff and erosion rates through the arroyos is insufficient to form the bokas by vertical entrenchment in the limestone terraces. Similar features have been described in the Mediterranean region as bogaz, grikes, dolines, poljes, or strugas, and in the Caribbean and North America as zanjones or karst corridors. Such features are attributed to karst phenomena that enlarge fractures by solution processes. The colloquial nomenclature is dependent on size and dimension of the feature. Nevertheless, the formational histories are likely tied to regional changes in base level and tectonic uplift/subsidence processes. In the case of Curaçao, the occurrence of numerous bokas in various stages of development allows for the creation of a model to explain the development of such features. Consequently, the presence of larger pocket beaches and interior bird-foot bays located within close proximity to the narrower bokas suggests the possibility that the features might actually be related. This study establishes a new multiphase model to explain the origin of these subaerial features that is based upon structural lineaments, groundwater flow patterns, cave development, sea-level transgression and regression, and subsequent wave widening and collapse.