A multiproxy analyses of sediment from a 4.3 m core extracted from 25 m water depth on the shelf of the northern Gulf of Aqaba suggest shifts in depositional environments over the past 4000 yrs. Foraminifera assemblages, grain-size distribution, sediment characterization, and radiocarbon age dating indicate several eco-stratigraphic zones including two periods of aridity from ~3900 to 2900 yr BP and ~1130 yr BP to present, a transitional period from ~2900 to 2500 yr BP, and an abrupt shift to wetter conditions between ~2500 to 1130 yr BP. Furthermore, this study records two foraminifera-barren horizons at 170 and 190 cm that correlate to grain size anomalies at that depth. A tsunami wave generated sometime during 2200-1800 yr BP is one possible explanation for this occurrence. Seismic stratigraphy indicates a reflector at approximately 3 m below the seafloor that delineates the boundary between a relict, coral fringing reef horizon, U8, and the overlying U9 strata. Sedimentation rates that adjust for sediment compaction suggest the sequence lies near the foraminifera-barren horizons at ~200 cm in the core. These data signify a dramatic environmental event possibly corresponding to reef termination on the Northern Gulf of Aqaba shelf.

Stratified cultural remains from the Roman to Late Islamic periods in the coastal zone of Aqaba, Jordan at the northern end of the Gulf of Aqaba and analyses of thirteen sediment cores provide evidence for changes in the depositional environment during the Holocene. Local tectonic subsidence likely formed a coastal embayment ca. 8000 yr B.P. that was subsequently filled by human-induced siltation by ca. 4000 yr B.P. base on radiocarbon and microfossil analyses. Overlying sedimentation is dominated by fluvial and aeolian processes until the first century B.C. when Early Roman-Nabataean mudbrick structures were built in this area. Strong lead and copper concentrations in the sediment appear to stratigraphically constrain the Chalcolithic and Roman layers. Furthermore, an examination of archaeological sites near Aqaba suggests that people migrated to avoid the flood waters of Wadi Yutim and Wadi 'Arabah rather than moving their settlements based solely on changing sea-level.

The reconstruction of ancient marine environments is an important task of the Earth Sciences, of great interest to geology, pure and applied, to oceanography and climatology, as well as to such fields as ecology and evolution. In principle, such reconstructions are based on the actualistic approach of "the present is the key to the past." Since the deciphering of past environmental changes, either nat ural or man-made, has considerable bearing on planning, the past may provide a key to the future. Paleoenvironmental interpretations in the marine realm are based to a great extent on assemblages of fossils recovered from ancient sediments in outcrops and from land-based or submarine drillings. Observable lateral sequences of assemblages in contemporaneous strata, the known or assumed functional or adaptive significance of preserved skeletal struc tures, as well as their evolution through time and space, provide by themselves indications of ancient environmental settings. In some cases even present-day eco logical considerations may be derived from analysis of fossils.

The variation in paleoclimate during the last deglaciation and Holocene were evaluated based on physical and biological variation in the bottom water oxygen level on the Baja margin in Soledad Basin. Sediment from core OXMZ MV99-PC14 raised from a depth of 540m off the Magdalena Margin of Baja California, Mexico was analyzed for the presence of benthic foraminifera, which are presumed to respond to marine productivity and change in bottom water oxygen. This location is an ideal location to study paleoclimate oscillation and ocean and atmospheric interactions due to its shallow sill depth (290m), high sediment rate (~110cm/kr), sensitivity to El Niño Southern Oscillation (ENSO) and ENSO-like variations. Computed Benthic Foraminiferal Oxygen Index (BFOI) and productivity (DSR-Factor3) variations down core showed enhanced productivity and low oxygen during the Mid Holocene. ENSO-like signals were recorded during the Mid Holocene (4-10 cal BP) when the climate witnessed a cold La Niña-like state. A changing pattern of ocean circulation, depth of thermocline and fluctuations in productivity occurred throughout Holocene in Soledad Basin. This was mainly due to the changing budget of oxygen, created primarily by variations in productivity which had an inverse relationship with oxygen levels. Similar variability was found in low and high latitude paleoclimate records from Chukchi shelf, Cariaco Basin, Santa Barbara basin, Point Conception, and Baja California.

Construction of the lower tidal lagoon at the Ayla Oasis Development in Aqaba, Jordan provided a unique opportunity to study the 3-D architecture of coastal plain sediment of the northern Gulf of Aqaba. Previous studies of sediment cores had identified a mid-Holocene transgression and a late Holocene regression. In this study, one cross-section of buried structures adjacent to the archaeological site of Tel el-Kheleifeh (8th-4th C. BCE) and two stratigraphic columns of 7 m-high outcrops that extended to a depth of 3.2 m below sea level were described and sampled for grain-size, SEM, and radiocarbon age analyses. The base of the section contains subtidal and beach sand and cobble gravel containing abundant shells and coral fragments. Three vertically stacked beachrock layers that developed in the intertidal zone indicate a rising sea level. The uppermost beachrock is found at an elevation of 1.3 m above present sea level and is constrained to be younger than 3.5 ka based on radiocarbon dating of shells. Raised reef, wave-cut notches, and other sea level indicators across the Gulf of Aqaba and northern Red Sea attest to a mid-Holocene highstand. A down-cutting event that eroded the beach sediment and is marked by an irregular unconformity and channels cut to depths below modern sea level. The channels are filled with a blue-gray gravel and sand with abundant rip-up clasts, terrestrial organic material, cross-bedding and convolute bedding which denote high flow velocities and rapid sedimentation. Radiocarbon dating of sediment above the channel constraint its age to before 3.1 ka. As rapid sea level change is not supported by regional evidence, the erosion and deposition of blue-gray channels are interpreted to represent inundation and drawdown of the sea by a tsunami. Similar erosion and deposition in low-lying areas has been documented in tsunamis in Sumatra, Chili, and the Kuril Islands.