An aquiclude is a saturated geologic unit that is incapable of transmitting significant quantities of water under ordinary hydraulic gradients. In Jamaica, there are three general types of aquiclude: Alluvium aquiclude is composed mainly of clay which is deposited by physical processes in river channels or on flood plains. Basement aquiclude is composed of volcanics and volcaniclastic sediments of Cretaceous ages and the overlying Yellow Limestone Group (calcarenites of Lower Eocene age). Coastal aquiclude is composed of soft marls and is patchily distributed along the coast of Jamaica.
A relatively impermeable underground confining unit, such as a clay. These saturated geologic units are incapable of transmitting significant quantities of water under ordinary hydraulic gradients. Very few formations fit the classical definition of an aquiclude.
A geologic formation that is saturated but is incapable of transmitting sufficient quantities of water to a well. Also, this type of formation is not capable of transmitting enough water to be considered as a significant part of the regional ground water system.