ENVIRONMENTAL, ECONOMIC, AND SOCIAL ASPECTS OF MARINE AGGREGATES EXPLOITATION

The progressive depletion of land sources of construction materials poses increasingly acute supply problems to the building industry. Stricter rules than currently exist in relation to environmental concerns and their effective enforcement, while undoubtedly laudable, would exacerbate the situation and preclude opening, in many instances, new land-quarries. The search for alternative sources led naturally to exploitation of marine deposits. Beaches and near-shore areas have long been tapped for relatively small amounts of sand and gravel, but the new, greatly-increased demands for these materials poses a serious threat to many shores. Tourism and mining, unavoidably, have come into conflict. Beach protection, and, with increasing frequency, 'renourishment', is antipodal to granulates' mining. Offshore dredging has in some cases triggered accelerated beach erosion. The general rise of sea-level, and the consequences of exceptional-strength storms, have worsened erosion and greatly disturbed - occasionally irreversibly - the local sedimentary budget and transit. Technological progress, and more and more sophisticated equipment, permit greater efficiency in, and greater depth of, dredging operations. Besides their use for construction materials, the search for minerals in the marine domain also affects sands and gravels: placers and ores are available here, and mining in the coastal zone is no longer a marginal undertaking. Exploitation of 'granulates' ranks today as the second most important marine mining activity after oil extraction. Hence it is a top-priority topic for Quaternary economic geologists and environment specialists alike, while public awareness has henceforth to be reckoned with. Communication and information techniques must consequently be designed and vigorously propagated.