The Bronze Age site of Kalamianos is located on a small limestone ridge on the Saronic coast, and there are no surface sources of fresh water. The region is dominated by down-to-the-south normal faults, including a major down-dropped block upon which the Kalamianos ridge and adjacent karst valley are located. Local mountains comprise Mesozoic limestone with well-developed brittle fractures and several dip-slip faults, including a major fault between the site and mountains. Brittle fractures were characterized and measured along a 1.4 km transect across the major fault and on a shorter transect near the archaeological site. Orientation data reveal several joint sets, and there are at least two generations of fracture development. One conjugate set of joints occurs parallel and perpendicular to beds. A second conjugate set of joints appears to be related to extension, possibly during lateral shear. All of these are characteristically short, tight to moderately open, lack fill, and show minor solution-enlargement. Older joints in the area occur as intersecting north-south and east-west sets. These joints are long and pervasive, often show considerable solution widening, have calcite coating, and contain lithified collapse breccia.

Near the Bronze Age site, relatively recent fracturing has reopened the older east-west joints. The thick calcite coating on joint surfaces is resistant to weathering and often stands several centimeters to decimeters in relief. When these joints were mapped in detail they proved to be pervasive across the archaeological site, though they are largely hidden by architectural rubble. We propose that these joints are the primary conduits for groundwater flow, which moves seaward under a large hydraulic head, to the site. Water sampled from one fracture was analyzed and passes U.S. drinking water standards. Detailed investigation of joints on-site reveals that locally they have been artificially opened, and we interpret these as Bronze Age wells. The location of these fractures shows a strong correlation with the location of architecture, revealing that the city developed along the joints, where fresh groundwater was readily available.