Today, Bir Tarfawi, Kharga and Dakhleh Oases all sit in Egypt's hyperarid Western Desert. A dearth of naturally occurring surface water coupled with <= 0.1 mm/y of precipitation, and evaporation rates > 2 m/y make Bir Tarfawi uninhabitable today, while Dakhleh and Kharga depend on borehole water to support human inhabitation. Yet in scattered locations dotting the Quaternary surfaces and deposits near each oasis, Paleolithic artefacts, fossil ungulate teeth, and snails record times when surface water did exist in wetlands, small ponds, and even large lakes. At Bir Tarfawi in Marine Isotope Stages (MIS) 5, 7, and 13, wetlands or small lakes supported freshwater snails, large herbivores, and hominins. Dakhleh Oasis hosted a large lake in MIS 6 that provided a deep reliable water supply for many millennia subsequently. ESR dates on fossils and tufa dates show thriving lacustrine and terrestrial ecosystems at Dakhleh during MIS 5, 7, 9,11, and 17, and in shorter episodes in MIS 1, 2, 3, 6, and 12. At Kharga Oasis, springs discharged along the Libyan Escarpment edge, but the water was ponded in small basins dammed within tufa deposits. These dated deposits and fossils attest that water existed there in MIS 2-11, and one spot dating to 2.3 Ma. This proxy evidence suggest that, thanks to higher rainfall and/or groundwater tables, sufficient water persisted for much of the Pleistocene, supporting food resources, like large herbivores and molluscs, to thrive and enabling hominin habitation. and activity in the Western Desert. (C) 2017 Elsevier Ltd. All rights reserved.

The sand and gravel mixtures found in the northern part of New York Harbor (i.e. Upper Bay) have long been attributed to the transport of coarse-grained sediments into the harbor from the Atlantic. A recent sedimentological study of New York Harbor suggested that the origin of this facies may have been from the East and Harlem rivers. Today, there are no tributaries supplying sediment to the East River Harlem River system. A review of oceanographic and historical data and a detailed bottom sediment mapping program has established the historical drainage changes in New York City and the effect on sediments supplied to the East River Harlem River system. Before the 18th Century, the East River and the Harlem River were major suppliers of coarse sediments to New York Harbor. However, development and filling in of almost all of New York's tributaries have cut off this sediment supply. The decrease in surface drainage has increased the danger of New York City flooding from Nor'easters and hurricanes. Finally, this research has shown that there are three, not two, sources of sediment for New York Harbor.

In the northeastern Sahara, electron spin resonance (ESR) dating of when animals lived documents their habitability in Dakhleh Oasis, Egypt. A Middle Pleistocene paleolake(s) covered >1700 km(2). At eastern Locality Dak348, 10 m thick, remnant lacustrine marls yielded Pleistocene fauna, rare artefacts, and plant casts. No obvious unconformity exists within these deposits. From upper horizons, a hartebeest tooth ESR dated at 195 +/- 11 ka, correlates with Marine Isotope Stage (MIS) 7, while molluscs from a stratigraphically higher horizon averaged 89 +/- 10 ka, correlating with MIS 5a/b. At western Locality Dak006, upslope deflation has left a temporally mixed surficial lag. Numerous lagged tooth fragments, independently dated by ESR, correlate with MIS 5 through 17. Fragments from a slope sand unit correlate with MIS stages 3 through 6. One bovid tooth associated with Younger Middle Stone Age artefacts in the base of the sand dated at 84 +/- 7 ka (MIS 5a/b). Molluscs from Romano-Byzantine backdirt at a breached artesian vent dated to 8-15 +/- 1 ka, suggesting that ponds formed during MIS 1 and 2. Even without well defined sedimentary contexts, ESR frequency data indicate that the oasis was habitable for herbivores during at least twelve stages in the Mid-Late Quaternary, and, therefore, likely also for humans. (C) 2015 Elsevier Ltd and INQUA. All rights reserved.

Electron spin resonance (ESR) dating can date many materials, including hydroxyapatite in enamel and some fish scales, aragonite and calcite in corals, molluscs, some travertine and calcrete, and quartz from ash, fluvial deposits, and some flint. Dating studies using these materials have numerous potential applications in many varied Quaternary settings. ESR dating uses signals resulting from trapped charges created by radiation in crystalline solids. Ages are calculated by comparing the accumulated radiation dose in the dating sample with the internal and external radiation dose rates produced by natural radiation in and around the sample and produced by cosmic radiation. When compared to other dating techniques, age agreement has been excellent for teeth, corals, molluscs, and quartz. Recent improvements have included using a more complex modelling technique to calculate the cosmic dose rates and more detailed modelling techniques for dealing with variable external dose rates. Methods in development include using quartz from buried fluvial valleys to date geomorphic surfaces and using the signals in barnacles and benthic foraminifera for dating fossils or their associated sediment. New chronometer applications recently developed include using coral and mollusc dates to build sealevel curves and to monitor volcanic activity and tectonic uplift, using tooth and mollusc dates to assess water availability in deserts, and using isochron data to assess U uptake processes into teeth. When coupled with other geochemical and geomorphological techniques, ESR can provide the chronometric control to build paleoclimatic and other paleoenvironmental records. Many other applications are possible, from heating studies for artefacts to dating sulphates and other minerals on distant planets.

Kharga Oasis, in Egypt's hyperarid Western Desert, today lacks naturally occurring surface water. Near Kharga, large tufa deposits ranging from a few hectares to more than 10 km(2) in area dot the edge of the Libyan Plateau. These, and lacustrine sediment, record intervals during the Pleistocene when wetlands, ponds, and small freshwater lakes provided water to enable herbivore and human inhabitation. Along with Pleistocene fossils, archaeological finds in the area include artifacts from Earlier Stone Age, Middle Stone Age, Later Stone Age, and younger cultural materials. ESR analysis was used to date freshwater mollusc shells (Melanoides tuberculata and Gyraulus) found in tufas and lake silts at Wadi Midauwara, Matana, and Bulaq. In some units, multiple gastropod populations from different times have been preserved as a mixed deposit, while several others appear to only preserve a single population. The mollusc dates suggest that freshwater existed sporadically at Bulaq and Matana during Marine (Oxygen) Isotope Stages (MIS) 2 and 4. At Midauwara, standing freshwater existed during the MIS 7/6 and 6/5e boundaries, and repeatedly in MIS 5-2. Molluscs and water also existed during the earliest Pleistocene, at similar to 2.4 +/- 0.4 Ma, which could have enabled the first hominin migration out of Africa via the Western Desert.

Receiving <0.1 mm/y of precipitation, Egypt's hyperarid Western Desert, today lacks naturally occurring surface water. Artesian spring deposits, tufa deposited by springs and carbonate-rich silty lacustrine sediment attest that oases in the Western Desert had surface water during the Pleistocene. Paleolithic artefacts, fossil ungulate teeth, and snails occurring within the Pleistocene deposits and dotting the surface record times when higher rainfall and/or groundwater tables during pluvial events allowed surface water to exist in wetlands, small ponds and lakes, enabling hominin habitation. Archaeological finds ranging from Early to Later Stone Age (ESA-LSA) occur in gravel lags, within sedimentary deposits, and on the older geomorphic surfaces. Near Kharga, large tufa deposits ranging from a few hectares to more than 10 km(2) in area, such as Matana and Medauwara, dot the edge of the Libyan Plateau. Molluscs were dated using standard ESR protocols. To test for reworked fossils, multiple samples from a single sample were dated independently. In some units at Medauwara, multiple gastropod populations from different times have been preserved, while others appear to only preserve a single population. To see the effects of the cosmic dose rate on ESR ages, ages were calculated using zero cosmic dose rate, the full modern cosmic dose rate, and time-averaged cosmic and sedimentary dose rates. For gastropods from Matana, no significant difference in ESR ages resulted from different cosmic dose rate assumptions. Therefore, at Matana 2, the shells dated at 27.7 +/- 1.9 assuming time-averaged external dose rates, while at Matana 3, they averaged 65.1 +/- 4.1 ka, suggesting that water was present for hominin use at times during OIS 2 and 4. (C) 2012 Published by Elsevier B.V.

Sealevel curves are best developed on tectonically stable coastlines, like San Salvador, where eolianites preserve transgressive and regressive phases associated with Quaternary high seastands, while reef facies mark the highstands. At 11 locations around San Salvador, terrestrial molluscs (Cerion) from the eolianites, lagoonal bivalves (Codakia), and corals from the highstand deposits were dated by ESR. Volumetrically averaged sedimentary dose rates were calculated from sedimentary geochemistry and time-averaged cosmic dose rates from each sample’s current and past geologic contexts.Rice Bay Formation corals dated at 3.9±0.3 to 7.1±0.4ka (OIS 1). Minimum ages for the Cockburn Town Member’s regressive phase ranged from 49±6 to 75±8ka, correlating with OIS 3–4. Codakia dates showed that an OIS 5a sealevel approached modern levels at 91–78ka. In situ corals from the Cockburn Town Reef averaged from 127±6 to 138±10ka, correlating well with OIS 5e. Ages from the Reef’s rubble zones hint that some coral reefs grew as early as OIS 7, but were likely reworked during OIS 5. San Salvador preserves deposits from three mid to late Quaternary highstands above, and as many as three that closely approach, modern sealevel.