Amazonian magnetostratigraphy: Dating the first pulse of the Great American Faunal Interchange

The chronostratigraphy of the youngest Neogene deposits of the Amazon Basin, which comprise the Madre de Dios Formation in eastern Peru, remains unresolved. Although ⁴⁰Ar/³⁹Ar dates on two volcanic ashes from this formation in Peru provide critical baseline data points, stratigraphic correlations among scattered riverine outcrops in adjacent drainage basins remain problematic. To refine the chronostratigraphy of the Madre de Dios Formation, we report here the magnetostratigraphy of an outcrop on the Madre de Dios River in southeastern Peru. A total of 18 polarity zones was obtained in the ～65-m-thick Cerro Colorado section, which we correlate to magnetozones Chrons C4Ar to C2An (9.5–3.0 Ma) based on the prior ⁴⁰Ar/³⁹Ar dates. These results confirm the late Miocene age of a gomphothere recovered from the Ipururo Formation, which underlies the late Miocene Ucayali Unconformity at the base of the Cerro Colorado outcrop. The results also support earlier interpretations of a late Miocene age for other fossils of North American mammals recovered from basal conglomeratic deposits of the Madre de Dios Formation immediately above the Ucayali Unconformity. These mammals include other gomphotheres, peccaries, and tapirs, and their presence in South America in the late Miocene is recognized as part of the first pulse of the Great American Faunal Interchange.     

Keeping the stress off the sheep? Agricultural intensification, neoliberalism, and ‘good’ farming in New Zealand

Under neoliberal schemes like audit systems, consumer demands born of concerns about food safety, the environment and animal welfare are theoretically poised to influence agricultural production systems (Campbell and Le Heron, 2007). Whether such influences might reverse or redirect the trend toward environmentally-damaging rampant productivism of the 20th century hinges in part on the subjective positions of farmers and the ways in which they inform how farmers respond to policy and market signals.In this paper we argue the need for a genuine engagement with both the complexities of farmer subjectivity and the interactions amongst farmer subjectivity and agro-ecologies, and animal bodies in particular. This paper presents a case study of sheep farmers on the South Island that reveals contestation and transitions in traditional markers of “good farming”, particularly animal health. We observe how such transitions arise from reconfigurations of the relationships between agro-ecological, political and social histories. In this paper’s formulation, neither state subsidies nor neoliberalism in agriculture is primary cause or ultimate effect of the transformation of agricultural practice. Rather, changes in the political economy expose contradictions in farmer subjectivities, the resolution of which may block or reinforce trends suggested by the political economy. We suggest that contested ideas about animal health within the social field of pastoral farming in New Zealand makes it possible that New Zealand’s sheep growers may take the high road of best environmental practice via highly audited environmental standards of production demanded by elite consumer markets, or that they may remain in the intensifying trajectory of continuing to drive the sheep’s body to its maximum possible intensity of production. The mixed legacy of neoliberal reform is that it has simultaneously enabled both of these contradictory trajectories in New Zealand pastoralism.     

Keck Observations of Solar System Objects: Perspectives for Extremely Large Telescopes

From differential tracking techniques, required for appulse observations of KBOs with Laser Guide Star Adaptive Optics (LGSAO), to developing methods for collecting spectra at the precise moment of a predicted impact, each Solar System observation conducted on a large telescope presents a unique set of challenges. We present operational details and some key science results from our science program, adaptive optics observations of main belt asteroids and near earth objects; as well as the technical and operational details of several Keck Solar System observations conducted by other teams: the impact of Shoemaker-Levy 9 on Jupiter, volcanoes on Io, the Deep Impact mission to Comet 9P/Tempel 1, and recent observations of Pluto’s moons Nix and Hydra. For each of these observations, we draw from our Keck experience to predict what challenges may lie ahead when similar observations are conducted on next generation telescopes.     

The 6dF Galaxy Survey: final redshift release (DR3) and southern large-scale structures

We report the final redshift release of the 6dF Galaxy Survey (6dFGS), a combined redshift and peculiar velocity survey over the southern sky  (| b | > 10°)  . Its 136 304 spectra have yielded 110 256 new extragalactic redshifts and a new catalogue of 125 071 galaxies making near-complete samples with  ( K , H , J , r _F, b _J) ≤ (12.65, 12.95, 13.75, 15.60, 16.75)  . The median redshift of the survey is 0.053. Survey data, including images, spectra, photometry and redshifts, are available through an online data base. We describe changes to the information in the data base since earlier interim data releases. Future releases will include velocity dispersions, distances and peculiar velocities for the brightest early-type galaxies, comprising about 10 per cent of the sample. Here we provide redshift maps of the southern local Universe with   z ≤ 0.1  , showing nearby large-scale structures in hitherto unseen detail. A number of regions known previously to have a paucity of galaxies are confirmed as significantly underdense regions. The URL of the 6dFGS data base is http://www-wfau.roe.ac.uk/6dFGS .     

A GEOGRAPHICAL ANALYSIS OF IMAGE INTERPRETATION METHODS

Image interpretation methods, procedures for relating image pattern to ground conditions, are essential to our use of remote sensing imagery. These methods can be analyzed in respect to the role of ancillary information in the image interpretation process. In general, those procedures that are comparatively independent of ancillary information can be applied in varied geographic settings. Because almost all interpretation procedures depend to some extent upon ancillary information, a detailed and integrated knowledge of the cultural and physical landscape is a prerequisite for both manual and automated interpretation procedures.     

Bootstrapped models for intrinsic random functions

Use of intrinsic random function stochastic models as a basis for estimation in geostatistical work requires the identification of the generalized covariance function of the underlying process. The fact that this function has to be estimated from data introduces an additional source of error into predictions based on the model. This paper develops the sample reuse procedure called the bootstrap in the context of intrinsic random functions to obtain realistic estimates of these errors. Simulation results support the conclusion that bootstrap distributions of functionals of the process, as well as their kriging variance, provide a reasonable picture of variability introduced by imperfect estimation of the generalized covariance function.This paper was presented at Emerging Concepts, MGUS-87 Conference, Redwood City, California, 13–15 April 1987.     

Chemical denudation rates in Kärkevagge, Swedish Lapland

This study examines the spatial and temporal variability of chemical denudation rates in Kärkevagge, northern Sweden. The chemical flux rates within the valley are strongly influenced by the local geology. Chemical denudation rates determined for the study period are more than double those previously reported in the literature for this valley. Rates of greater than 46t km⁻² a⁻¹ were measured at the valley mouth over the course of the melt season. This difference is likely due to differences in measurement technique compared to that used by past researchers. This rate is also much higher than for other arctic and alpine watersheds. Chemical denudation in Kärkevagge is comparable to larger temperate rivers. The rapid chemical denudation in Kärkevagge is likely due to sulfide weathering creating acid solutions.     

Radar detection of Vesta

Asteroid 4 Vesta was detected on 1979 November 6 with the Arecibo Observatory's S-band (12.6-cm-wavelength) radar. The echo power spectrum, received in the circular polarization opposite to that transmmited,, yields a radar cross section of (0.2 ± 0.1)πa², for a = 272 km. The data are too noisy to permit derivation of Vesta's rotation period.     

Subsidence rates for the Southeastern Hawaiian Islands determined from submerged terraces

Detailed bathymetric maps of the southeastern Hawaiian Islands reveal terraces west of Lanai and west of Hawaii; these can be correlated with glacial maxima to provide island subsidence rates of 1.9 and 2.4 mm/yr, respectively. These data agree in general with subsidence rates determined by other means. Plots of present depth versus age for these terraces show that subsidence of the island of Hawaii has remained relatively constant since 600 ka; thus the magma production of the Hawaiian hotspot has been nearly steady for this period. These subsidence rates also explain why evidence of sea levels higher than present is not found on the islands southeast of Oahu.     

Comparative advantage and distant water fishing fleets: The Australian east coast tuna longline fishery

A coastal state benefits from importing the services of a distant water fishing nation (DWFN) fleet if the DWFN has a comparative advantage in exploiting the fishery, based on factors such as market access, costs or technology. The paper compares the activities of the Australian and Japanese vessels in the east coast tuna longline fishery and finds the Australian vessels receive higher prices, have higher costs and use a different technology from the Japanese fleet. These differences suggest a pattern of comparative advantage which can lead to Australia benefitting from importing the services of the Japanese fleet.