THE HYDROGEOLOGY OF THE MIOCENE – PLIOCENE ROCKS OF THE PIEDMONT OF THE CORDILLERA CENTRAL, NORTHWESTERN DOMINICAN REPUBLIC

A humanitarian effort, including a hydrogeologic reconnaissance expedition to the piedmont of the northwestern Dominican Republic, was conducted in July 2002 between the latitude of 71º25’W to 71º30’W and longitude 19º24’N to19º36’N within the Martin Garcia quadrangle. The towns of Los Amaceyes and Cabeza de Toro were visited to determine how to effectively better serve the potable water demand in this extremely arid region. These two communities are located at about 100 meters above mean sea level in the northwest portion of the Martín García quadrangle in northwestern Dominican Republic. At present the people in these two communities obtain their water from nearby rivers or ponds. This water, however, is contaminated with bacteria. Previous attempts to drill and install water wells in the vicinity of these two communities have either failed to produce water or have produced water that was too hard to be acceptable due to a poor interpretation of the geology of the region. The geological reconnaissance resulted in mapping the geology of a thin sequence of Miocene-Pliocene clastics known regionally as the Gurabo Formation. Regional tilt of the Gurabo limestones and unconsolidated sandstones provides evidence for future placement and installation of water wells down dip of the suspected regional flow of groundwater, which starts in the piedmont and flows to the south in the field study area. No neotectonic evidence was found to have contributed to the approximate 9ºNE tilt of the clastic rocks of this area. It was determined that the Cretaceous Amina Schist unconformably underlies the thin sequence of clastic rocks in the field area and is not a major aquifer bearing formation in the area.