to the search for others like it; the finds that resulted were some of the largest oil fields in the United States. The sedimentary layers over the dome are themselves arched into a shape conforming to the underlying dome, so the structure forms a perfect trap for hydrocarbons which would otherwise migrate to the surface. The field contains 30 separate pools or producing horizons, ranging in depth from 800 to . The oil-bearing strata under the salt dome consist of porous sands with some interspersed clay. The Goose Creek field is the first place where subsidence of the land over the oil field was definitively attributed to the extraction of petroleum. Subsidence over the Goose Creek field is well documented and particularly dramatic; parts of the field which were once above-water are now wholly or partially submerged, and the area of subsidence almost exactly conforms to the boundary of the productive region. The connection between extraction and subsidence was first recognized by geologists Wallace Everette Pratt and D.W. Johnson, who published their findings in a 1926 paper. By this year, after about ten years of active pumping, most of the productive area of the field had subsided three feet, and the submerging of the facilities had already become obvious to field operators. Along with the subsidence, surface faulting has been observed, and motion along these faults – although minimal compared to motion along faults in areas in which the seismic activity is due to tectonic forces – has been sufficient to damage buildings and be felt in the local area. One of the faults in the Goose Creek area, first observed in 1925, shows a vertical displacement of 0.4 meter, along a length of over 700 meters. Subsidence of land due to either oil or groundwater extraction is now widely recognized, and the Gulf Coast is one of many places in the world in which it has become a serious problem. In the present day, oil fields underneath sensitive areas, such as cities, are usually re-pressurized with water or gas to prevent the land above them from collapsing into the vacated space. History, operations, and production Bubbles of methane gas coming up in the shallow water along the shoreline of Galveston Bay alerted early prospectors in 1903 to the possibility of an oil field in the area. The first attempts to develop the field followed shortly, but none of the