Hampton, Monty A., Torresan, Michael E., and Barber, Jr., John H., 1997, Sea-floor geology of a part of Mamala Bay, Hawaii: Pacific Science, v. 51, n. 1, p. 54-75. Reproduced by permission of the University of Hawaii Press.
Mamala Bay lies off the south shore of the island of Oahu, Hawaii, between Diamond Head and Barber's Point (Figure 1). Notable nearby landmarks are Pearl Harbor and the city of Honolulu. We were contracted by the U.S. Army Corps of Engineers (USACE) and the U.S. Environmental Protection Agency (EPA) to map the sea floor and shallow sub-sea floor in part of the bay, as well as to collect and analyze sediment samples, in support of their programs to regulate and monitor the discharge of dredged material at offshore disposal sites. The study area covers about 200 km2 between 21°12' and 21°17' north latitude and 157°49' and 158°03' west longitude (Figure 1). Mamala Bay has been used as a repository for sediment dredged mainly from Pearl and Honolulu Harbors for more than a century, particularly at the three sites shown in Figure 1. The old Pearl Harbor and Honolulu Harbor sites have not been used since the South Oahu site was designated in 1980. Since that time, a total of approximately 4.5 million m3 of material has been dredged from Honolulu and Pearl Harbors, and other areas.
In this paper we present the geologic results of our mapping and sampling program, focusing primarily on the bathymetry, sea-floor morphology, and sea-floor materials. Inferences are made about sediment transport. The geo-environmental aspects of the dredged-material deposits are the subject of a paper to be presented elsewhere (see also, Torresan et al., 1994).