10 Hygiea: ISO Infrared Observations

Observations of emissivity features of 10 Hygiea have been made for the first time in the relatively unexplored thermal-infrared wavelength region with the ISO (Infrared Space Observatory) satellite. Spectrophotomer (PHT-S) and short wavelength spectrometer (SWS) spectra of 10 Hygiea, obtained at 5.8-11.6 and 7-45 μm, respectively, are presented. In order to remove the thermal emission continuum, an advanced thermo-physical model has been applied to the observational data. To better interpret the spectral features above the thermal emission continuum, we compared the ISO observations with laboratory spectra available in the literature. Several laboratory experiments on minerals and meteorites have been performed to complete the analysis and to study the spectral behavior at various grain sizes. A possible spectral similarity with CO carbonaceous chondrites at small grain size is demonstrated.     

Petrology of sapphirine granulite and associated sodic gneisses from the Indian Head Range, Newfoundland

Migmatitic granulites from the Indian Head Range (IHR) are dominated by granoblastic, Opx-bearing (quartz) dioritic gneiss with subordinate garnet+orthopyroxene+biotite+albite (±quartz±microcline±cordierite±sillimanite) gneiss and comparatively biotite-rich, sapphirine+cordierite+orthopyroxene+albite (±microcline±sillimanite±corundum) gneiss. The latter contains at least two generations of sapphirine and cordierite, one apparently predating migmatization, the other associated with or following this event. Mineral thermobarometers yield temperatures up to 800 °C at 8 kbar. The IHR granulites have very high δ¹⁸O values (+10.8 to +14.5) which most likely indicate a sedimentary precursor. Their REE and HFSE contents resemble the trace element signature of post-Archean Australian shale (PAAS). Lithological analogues from other Grenvillian inliers in western Newfoundland have similar oxygen isotopic and immobile-element signatures. They too are interpreted as metasedimentary rocks. The IHR rocks, however, have unusually sodic compositions (e.g., Na₂O/CaO and Na₂O/K₂O=2.1–22.5 and 0.93–13.8, respectively) and contain albite or sodic oligoclase despite their high metamorphic grade. The geochemical data indicate that these rocks were albitized prior to high-grade metamorphism. No counterpart of this event is recorded in granulites from the other inliers, indicating that the IHR may be highly allochthonous with respect to these other Grenvillian terranes.     

Geographical Research about African Americans: A Survey of Journals, 1911–1995

This paper surveys research about African Americans in six geography journals between 1911 and 1995. 176 journal articles about African Americans were identified. A chronological analysis of a subset of these articles shows that it was not until the 1960s that African Americans were studied to any appreciable degree by geographers. Since that time, geographers have continued this research, but unevenly; annual output varies widely. Popular topics have included considerations of spatial distributions, social problems, political participation, the development of black residence areas, and historical and cultural studies of African Americans. Recent research in this area has problematized the concept of “race” and investigated the mutual constitution of racial identity and place.     

The correlation of summer precipitation in the southwestern U.S.A. with isotopic records of solar activity during the medieval warm period

Decreased solar activity correlates with positive cosmogenic isotope anomalies, and with cool, wet climate in temperate regions of the world. The relationship of isotope anomalies to climate may be the opposite for areas influenced by monsoonal precipitation, i.e., negative anomalies may be wet and warm. Petersen (1988) has found evidence for increased summer precipitation in the American Southwest that can be shown to be coincident with negative¹⁴C anomalies during the Medieval Warm Period. The present study compares palynological indicators of lake level for the Southwest with Petersen's data and with the¹⁴C isotope chronology. Percentages of aquatic pollen and algae from three sites within the Arizona Monsoon record greater lake depth or fresher water from A.D. 700–1350, between the Roman IV and Wolf positive isotope anomalies, thereby supporting Petersens's findings. Maximum summer moisture coincides with maximum population density of prehistoric people of the Southwest. However, water depth at a more northern site was low at this time, suggesting a climateisotope relationship similar to that of other temperate regions. Further analysis of latitudinal patterns is hampered by inadequate¹⁴C dating.     

The changing spatial distribution of socio-economic groups employed in manufacturing in Great Britain, 1971–1981

In this paper an attempt is made to study the spatial division of labour in Britain, through an investigation of the changing structure of employment in the manufacturing sector between 1971 and 1981. The separate impacts of loss in the volume of manufacturing employment, change in the balance between production and non-production activities in the occupational structure and the spatial shift of the population employed in manufacturing upon spatial variations in manufacturing employment change are tentatively identified. Data on the socio-economic composition of the population employed in manufacturing from the Small Area Statistics of the Censuses of Population for 1971 and 1981 are used to measure the impact of these processes at the local labour market area (LLMA) scale and to draw conclusions for the future employment prospects of different parts of Britain.     

Anthracitization of coals in the South Wales coalfield

Investigations by the Institute of Geological Sciences on potential geothermal water sites in the coalfield of South Wales have been reported. They are of considerable interest and revive the controversy about the nature of the heat-source responsible for the anthracitization of some coals in this classic area. In the absence of exposed post-Carboniferous igneous rocks in the coalfield, general opinion has favoured heat generation by friction along faults or “disturbances”. We re-examine the evidence in the light of more recent geophysical and geochemical investigations which suggest the possibility of igneous intrusions at a depth of about 3.5 km or shallower. The likely age of such intrusions is also considered. High seismic velocity basement rocks rise to only 2.5 km beneath the surface of the Carboniferous in the northwestern anthracitized zone of the coalfield and we suggest that anthracitization in South Wales is not the result of depth of burial nor of frictional heat but of proximity to a magmatic heat source associated with crystalline rocks of the basement.     

Comparing tiltmeters for crustal deformation measurement--a preliminary report

A collection of high-precision tiltmeters is being operated at Pinon Flat Observatory, southern California, both to compare instruments and to measure tectonic deformation. We report on 1.2 years of data from four of these: two Michelson-Gale long fluid tiltmeters, one long center-pressure tiltmeter, and a shallow borehole tiltmeter. The three long-base instruments are all located on the same baseline, with a precise leveling line running between their end-monuments. At nontidal frequencies, only the two Michelson-Gale instruments show some coherence (gamma 2 = .3 for periods of 2 to 4 days), while the center-pressure instrument is correlated with air temperature at periods from a few days to a few weeks. The most stable tilt record shows a secular rate of 0.28 mu rad/a, which may be real. Over much longer times, leveling to specially stabilized bench-marks should confirm this. Comparing instruments has identified more and less successful measurement techniques; it appears that low-noise data will most probably be produced only by relatively complex and expensive instruments, though even for these, the operating costs over any reasonable lifetime will exceed the capital cost. Even the best existing sensors must be improved to measure continuous tectonic motions.