Pollen abundances, and temperature and precipitation reconstruction for the Eocene to Oligocene transition in northern high latitudes

A profound global climate shift took place at the Eocene-Oligocene transition (~33.5 million years ago) when Cretaceous/early Palaeogene greenhouse conditions gave way to icehouse conditions (Zachos et al., 2001, doi:10.1126/science.1059412; Coxall et al., 2005, doi:10.1038/nature03135; Lear et al., 2008, doi:10.1130/G24584A.1). During this interval, changes in the Earth's orbit and a long-term drop in atmospheric carbon dioxide concentrations (Pagani et al., 2005, doi:10.1126/science.1110063; Pearson and Palmer, 2000, doi:10.1038/35021000; DeConto and Pollard, 2003, doi:10.1038/nature01290) resulted in both the growth of Antarctic ice sheets to approximately their modern size (Coxall et al., 2005, doi:10.1038/nature03135; Lear et al., 2008, doi:10.1130/G24584A.1) and the appearance of Northern Hemisphere glacial ice (Eldrett et al., 2007, doi:10.1038/nature05591; Moran et al., 2006, doi:10.1038/nature04800). However, palaeoclimatic studies of this interval are contradictory: although some analyses indicate no major climatic changes (Kohn et al., 2004, doi:10.1130/G20442.1; Grimes et al., 2005, doi:10.1130/G21019.1), others imply cooler temperatures (Zanazzi et al., 2007, doi:10.1038/nature05551), increased seasonality (Ivany et al., 2000, doi:10.1038/35038044; Terry, 2001, doi:10.1016/S0031-0182(00)00248-0) and/or aridity (Ivany et al., 2000, doi:10.1038/35038044; Terry, 2001, doi:10.1016/S0031-0182(00)00248-0; Sheldon et al., 2002, doi:10.1086/342865; Dupont-Nivet et al., 2007, doi:10.1038/nature05516). Climatic conditions in high northern latitudes over this interval are particularly poorly known. Here we present northern high-latitude terrestrial climate estimates for the Eocene to Oligocene interval, based on bioclimatic analysis of terrestrially derived spore and pollen assemblages preserved in marine sediments from the Norwegian-Greenland Sea. Our data indicate a cooling of ~5 °C in cold-month (winter) mean temperatures to 0-2 °C, and a concomitant increased seasonality before the Oi-1 glaciation event. These data indicate that a cooling component is indeed incorporated in the d18O isotope shift across the Eocene-Oligocene transition. However, the relatively warm summer temperatures at that time mean that continental ice on East Greenland was probably restricted to alpine outlet glaciers.

Stable oxygen isotope ratios of benthic and planktonic foraminifera from early Miocene sediments of DSDP Site 90-593 on the Challenger Plateau, Pacific Ocean (Table 1)

Oxygen isotope data are compared with relative abundances of selected planktic foraminifera through a ca. 15 m interval at DSDP Site 593 (Tasman Sea, southwest Pacific, 40°S) in which there are prominent changes in population sizes, as well as several evolutionary events. We focus on the relation between faunal and climatic histories. The base of early Miocene oxygen isotope Zone Mi1b (uppermost planktic foraminiferal Zone N.6) is identified from closesampled (c. 14 kyr) isotope records of Globigerina woodi and Cibicides kullenbergi. Chronostratigraphic interpolations, using the first occurrences of Globorotalia praescitula, G. mimea and Praeorbulina curva give an age estimate of ca. 18.4 Ma (cf. 18.1 -18.3 Ma for the base of the zone at DSDP Site 608 (type level, north Atlantic, 43°N) ). Another significant benthic delta18O enrichment event, informally designated as the base of zone "Mi1c", is identified 10 m higher in the sequence at ca. 17.8 Ma. Populations of Globoquadriau dehiscens and Globigerinoides trilobus (inferred to be near the southern margin of their distributions) either reduced considerably or withdrew, particularly in the vicinity of zone "Mi1c". A bioseries linking Globorotalia incognita with G. zealandica developed following the benthic delta18O enrichment spike at the base of Zone Mi1b; the latter species became extinct (at least regionally) just above the base of zone "Mi1c". In contrast, the apparently opportunistic Globorotlia praescitula increased dramatically in abundance at this time; there were also transformations in its architecture, leading to the evolutionary appearance of G. miozea. While planktic foraminifera abundances often do not closely covary with the detailed isotope records and tend to be more stable through time, the near coincidence of evolutionary and biogeographic events with isotopic events suggests at least indirect adaptive responses to climatic changes. Early Miocene middle-latitude planktic foraminiferal evolution, biogeography, and biostratigraphy, may be intimately connected with climatic history.

Distribution of deep-sea meiobenthos in surface sediments off North Carolina

Observations on the ecology and distribution of meiofauna occurring on the outer continental shelf and continental slope at depths from 50 to 2500 m in the region where the Blake Plateau cuts across the North Carolina slope are reported. Total numbers of meiofauna ranged from 151/100 cm**3 of sediment at 400 m to 1196/100 cm**3 of sediment at 250 m. Sediments of the upper region (50-500 m) consisted of medium-sized calcareous sands with relatively low organic carbon contents, while the deeper sediments (600-2500 m) consisted of sandy silts and silts with organic carbon contents 6-10 times that of the shallower sediments. Two basic faunas appear to be present in the areas investigated; a shallow-water fauna extending from 50 to 500 m and a deep-water fauna from 800 to 2500 m. The shallow-water fauna consists of nematodes (the dominant taxon) and relatively large numbers of harpactacoid copepods, ostracods, benthic foraminifera, polychaetes, gastrotrichs and several other groups, while below 500 m only nematodes and foraminifera are present in large numbers, the latter being especially abundant between 800 and 2000 m. A major change in the meiofauna occurs on the Blake Plateau between the depths of approximately 400-500 m and 600-750 m where the composition of the sediment changes from sand to silty sand. From 50 m to 400-500 m gastrotrichs, turbellaria, tardigrades, kinorhynchs, halicarids, hydrozoans, gnathostomulids, lamellibranchs and cumaceans are commonly encountered; these groups are absent below 500 m. In addition, there are significant reductions in the numbers of harpactacoids, ostracods, nemerteans and polychaetes below 500 m. Examination of the nematode population also show faunal differences between the shallower sediments (50-500 m) and the deeper sediments (600-2500 m). High indices of affinity exist among the faunas between 50 and 500 m and among the faunas between 800 and 2500 m; the fauna at 600-750 m represents a transition between these two regions, but it is more closely related to the deep-water fauna. Changes in the distribution of both the total meiofuna and also the nematodes are highly correlated with changes in sediments composition and bottom water temperatures. It is suggested that changes in grain size and accompanying changes in sources of nutrition, which are the results of Gulf Stream and other current activity, are the dominant environmental factors influencing the meiofauna of the area.

Modelled spatial and seasonal distribution of Blue Whiting (Micromesistius poutassou) larvae in the North-East Atlantic (1951 to 2005)

Blue whiting (Micromesistius poutassou, http://www.marinespecies.org/aphia.php?p=taxdetails&id=126439) is a small mesopelagic planktivorous gadoid found throughout the North-East Atlantic. This data contains the results of a model-based analysis of larvae captured by the Continuous Plankton Recorder (CPR) during the period 1951-2005. The observations are analysed using Generalised Additive Models (GAMs) of the the spatial, seasonal and interannual variation in the occurrence of larvae. The best fitting model is chosen using the Aikaike Information Criteria (AIC). The probability of occurrence in the continous plankton recorder is then normalised and converted to a probability distribution function in space (UTM projection Zone 28) and season (day of year). The best fitting model splits the distribution into two separate spawning grounds north and south of a dividing line at 53 N. The probability distribution is therefore normalised in these two regions (ie the space-time integral over each of the two regions is 1). The modelled outputs are on a UTM Zone 28 grid: however, for convenience, the latitude ("lat") and longitude ("lon") of each of these grid points are also included as a variable in the NetCDF file. The assignment of each grid point to either the Northern or Southern component (defined here as north/south of 53 N), is also included as a further variable ("component"). Finally, the day of year ("doy") is stored as the number of days elapsed from and included January 1 (ie doy=1 on January 1) - the year is thereafter divided into 180 grid points.

Types of work performed using resurfacing, restoration, rehabilitation, and reconstruction federal highway funds : report to the chairman, Subcommittee on Investigations and Oversight, Committee on Public Works and Transportation, U.S. House of Representatives /

"B-212809"--Prelim. p. [1].

Long-term changes in beach fauna at Duck, North Carolina /

Long-term changes in the beach fauna at Duck, North Carolina, were investigated. Twenty-one stations located on three transects on the oceanside and twenty-four stations located on three transects on the sound side were sampled seasonally from November 1980 to July 1981. The data collected in this study were compared to a previous study conducted in 1976 (Matta, 1977) to investigate the potential effects of the construction of the CERC Field Research Facility pier on the adjacent beaches. No effects on the benthic fauna were found. Changes observed in the benthic macrofauna on the ocean beaches were well within the range attributable to the natural variation of an open coast system. The ocean beach macrofauna was observed to form a single community migrating on an off the beach with the seasons. On the sound beaches, changes were detected in the benthic macrofauna; however, these were attributed to a salinity increase during the 1981 sampling year. (Author).

Effects of channel relocation and proposed bridge construction on floodflows of the Catawba River near Marion, North Carolina /

Mode of access: Internet.

In defense of the independence of the judiciary : speech of Hon. Josiah W. Bailey of North Carolina in the Senate of the United States, July 12 and 13, 1937.

"Not printed at government expense."

Sermons on practical subjects: to which is added, a farewell discourse, delivered at Paisley in April and May 1768.

Mode of access: Internet.

Comparison of numerical and physical hydraulic models, Masonboro Inlet, North Carolina /

"June 1977."

Comparison of numerical and physical hydraulic models, Masonboro Inlet, North Carolina : Appendix 1, fixed-bed hydraulic model results /

"June 1977."

Comparison of numerical and physical hydraulic models, Masonboro Inlet, North Carolina : Appendix 2, numerical simulation of hydrodynamics (WRE) /

"June 1977."