Geology topics
Source-linked reports with geographic coverage including Okinawa.
This series of military geology reports on Okinawa is part of the Corps of Engineers Post Hostilities Mapping Program. The purpose of this survey is twofold. The first is to collect scientific information through field study; the second is to publish it in a form that is usable by the United States Armed Forces and Civil Administrators.
Wall-like ridges of limestone that stand well above the surrounding terrain are an interesting phenomenon on the island of Okinawa. These ridges rim a variety of topographic features, but all are believed to represent the same formative processes. Rimming ridges or walls occur along the banks of streams crossing areas of limestone, along the upthrown sides of faults, around a sink hole, and along terrace edges. The limestone walls of Okinawa are believed to have formed by the cementation, or casehardening, of steep exposures of poorly consolidated limestone, followed by differential erosion which brings the cemented zones into relief. Cementation occurs wherever poorly consolidated limestone is exposed to alternate wetting and drying. It is best developed, however, on steeply sloping exposures where no soil accumulates to hinder drying. Differential erosion results in part from slower solution of cemented limestone, due to its greater density, and in part from accelerated solution in the surrounding soil-covered areas. Rampart walls along the seaward edges of terraces have been described from many Pacific islands and are present on many others. They are believed to be comparable to the walls of Okinawa and all are believed to have been formed under similar conditions.