The Carriacou hypothesis : bottomless stacked pots, a study in Amerindian freshwater procurement

Water procurement is difficult for people who live in dry environments. On the small, low islands in the Eastern Caribbean, where drought can be a common occurrence, residents have had to develop numerous techniques to secure and manage their water supply. Some researchers have noted that these droughts occurred in prehistory, and thus must have affected also the indigenous population of the region; but few have chosen to focus much attention on Amerindian freshwater management, and none have adequately explored how they survived on these islands during dry times. My research addresses these issues.

Recently, a number of bottomless clay pottery assemblages have been uncovered in the coastal zones of Carriacou and Barbados, two small, drought-prone islands in the Eastern Caribbean. A folk theory suggests the "potstacks" were used by Amerindians as a freshwater well casing. The purpose of this paper is to examine and test the efficacy of this "Carriacou hypothesis;" in particular, that during dry times Amerindians dug wells in the island coastal zone to tap into the edge of the freshwater lens, using the potstacks as a well casing.

I study this concept by examining what is known about Amerindian freshwater management in the Eastern Caribbean, and by documenting the extensive use of groundwater and well casings by the people of other arid regions. Then, I ground the Carriacou hypothesis in the hydrologic literature and develop the "Potstack System" theory to explain how it was possible to find fresh near-coast groundwater by digging shallow pits and lining them with collections of bottomless pottery. Finally, I take this system to the field to test its correspondence with the groundwater hydrology of Carriacou and Barbados. Here, I document relevant cultural information, test the depth and salinity of near-coast well water, and dig test pits in my own attempt to find freshwater.

My results show that island residents are well aware of the existence of near-coast freshwater, and that they dig shallow holes to collect it. Well measurements also support the Carriacou hypothesis and the Potstack System, indicating that groundwater becomes fresher with increasing distance from the coast, but that it will lie at a greater depth below the surface; thus, by striking a balance between depth and salinity in the coastal zone, one can dig shallow pits and procure slightly brackish -- but drinkable -- water. And although I did not find freshwater in my own test pits, I came to appreciate the problems involved with digging wells and the real need for a casing in these circumstances.

I conclude that the Carriacou hypothesis is not an unreasonable explanation for the utility of the Carriacou and Barbados potstacks, and that it provides a window for comparing the water procurement techniques of today to those that may have been used in the past.