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21.
A time-space model for the distribution of shoreline archaeological sites in the lake superior basin
Brian A. M. Phillips 《Geoarchaeology》1993,8(2):87-107
Archaeological site interpretation can be enhanced by consideration of related geological and geomorphological processes. Lake Superior has a history of glaciation, isostatic recovery, and water-level change. Two examples are given of shoreline sites at which interpretation is enhanced by an understanding of local geologic factors. The archaeologic history of the Lake Superior basin is reviewed, and three cultural traditions are recognized; (1) Paleoindian, (2) Archaic, and (3) Woodland. Three significant factors of geologic history are then discussed: (1) ice margin oscillation, (2) differential isostatic uplift, and (3) lake-level fluctuations. The factors reducing or improving shoreline archaeological site preservation are examined, and a summary model of shoreline site distribution for the Lake Superior basin is offered. It is concluded that the north shore provides the best potential for a complete archaeological record. © 1993 John Wiley & Sons, Inc. 相似文献
22.
The wedge‐shaped Moornambool Metamorphic Complex is bounded by the Coongee Fault to the east and the Moyston Fault to the west. This complex was juxtaposed between stable Delamerian crust to the west and the eastward migrating deformation that occurred in the western Lachlan Fold Belt during the Ordovician and Silurian. The complex comprises Cambrian turbidites and mafic volcanics and is subdivided into a lower greenschist eastern zone and a higher grade amphibolite facies western zone, with sub‐greenschist rocks occurring on either side of the complex. The boundary between the two zones is defined by steeply dipping L‐S tectonites of the Mt Ararat ductile high‐strain zone. Deformation reflects marked structural thickening that produced garnet‐bearing amphibolites followed by exhumation via ductile shearing and brittle faulting. Pressure‐temperature estimates on garnet‐bearing amphibolites in the western zone suggest metamorphic pressures of ~0.7–0.8 GPa and temperatures of ~540–590°C. Metamorphic grade variations suggest that between 15 and 20 km of vertical offset occurs across the east‐dipping Moyston Fault. Bounding fault structures show evidence for early ductile deformation followed by later brittle deformation/reactivation. Ductile deformation within the complex is initially marked by early bedding‐parallel cleavages. Later deformation produced tight to isoclinal D2 folds and steeply dipping ductile high‐strain zones. The S2 foliation is the dominant fabric in the complex and is shallowly west‐dipping to flat‐lying in the western zone and steeply west‐dipping in the eastern zone. Peak metamorphism is pre‐ to syn‐D2. Later ductile deformation reoriented the S2 foliation, produced S3 crenulation cleavages across both zones and localised S4 fabrics. The transition to brittle deformation is defined by the development of east‐ and west‐dipping reverse faults that produce a neutral vergence and not the predominant east‐vergent transport observed throughout the rest of the western Lachlan Fold Belt. Later north‐dipping thrusts overprint these fault structures. The majority of fault transport along ductile and brittle structures occurred prior to the intrusion of the Early Devonian Ararat Granodiorite. Late west‐ and east‐dipping faults represent the final stages of major brittle deformation: these are post plutonism. 相似文献
23.
Despite significant technological advances in emerging economies, the further development of clean energy technologies in developing countries remains crucial to reducing the greenhouse gas emissions associated with economic development. In this paper we address two significant gaps in the growing body of literature that has assessed the role of the Clean Development Mechanism in promoting the transfer of clean technologies to developing countries. First, we present a qualitative analysis of the governance of the Clean Development Mechanism in India. This provides a basis for understanding the extent to which and the ways in which governance may impact upon the likelihood that projects promote technology transfer. Second, we provide a novel quantification of the level and nature of technology transfer that has occurred in Indian Clean Development Mechanism projects, based on insights from literature on technological capability building. We find that the Clean Development Mechanism in India has produced a negligible number of projects that promote technology transfer if technology transfer is understood as a process of learning about technology. Together these qualitative and quantitative analyses show how politics and governance have contributed to the current form of the Clean Development Mechanism market in India, in which processes of building indigenous technological capabilities have been neglected. 相似文献
24.
Brian L. Phillips R. James Kirkpatrick Guy L. Hovis 《Physics and Chemistry of Minerals》1988,16(3):262-275
Solid-state 27Al, 29Si and 23Na MAS NMR spectra have been obtained for an Al,Si ordered low albite to low microcline ion exchange series for which unit-cell parameters and 29Si NMR data have previously been reported. 27Al δi vary continuously with composition from 63.4 (±0.5) ppm for albite to 58.9 (±0.5) ppm for microcline, and parallel the 29Si chemical shifts assigned to the T2m-site. The 27Al and 29Si chemical shifts for this series correlate well with composition-dependent lattice parameters, most notably cell volume and the angle [201]1b. The linewidths of the 29Si and 27Al resonances indicate a significant amount of structural disorder in the intermediate compositions due to Na, K substitution. The 1 σ width of the distribution of average Si-O-T angles for each T-site is estimated to be about 1° for the Or33 sample. The average 23Na δi varies monotonically from -8.5 (±1) ppm for albite to -24.3 (±1)ppm for Or83. Similarly, the average 23Na nuclear quadrupole coupling constant decreases from 2.60 to 1.15 (±0.05) MHz and the asymmetry parameter of the electric field gradient increases from 0.25 to 0.6 with increasing K-content from albite to Or83. The observed variations in the quadrupole coupling parameters are consistent with simple electrostatic calculations. Higher resolution 23Na spectra of the intermediate compositions obtained at 11.7 T indicate the presence of an inhomogeneous linebroadening which is related to the distribution of Na-environments. A model based on a random distribution of local compositions does not simulate the spectra, suggesting that the distribution of Na is skewed toward Na-rich clusters. Observation of the 23Na NMR lineshape of Or49 after short periods of heat treatment indicate that 23Na NMR is very sensitive to the changes in the Na, K distribution accompanying the early stages of exsolution. Reversible changes occur after heating at 530° C for 3 h, whereas heating at 600° C produces no changes, possibly bracketing the position of the coherent spinodal for Al, Si ordered alkali feldspars at this composition. 相似文献
25.
HF radar stations (utilizing the spaced-antenna partial-reflection technique) located at Adelaide (35°S, 138°E) and Mawson Station (67°S, 63°E) have observed horizontal mesospheric winds continuously since mid-1984. Observations in the period 1984–87 are compared with the Northern Hemisphere [latitude conjugate] stations of Kyoto (35°N, 136°E) and Poker Flat (65°N, 147°W), and with satellite-derived circulation models. Particular reference is made to the equinoctial changeovers in zonal flow and to the temporal and altitude variations in the planetary wave activity at Mawson and Adelaide. 相似文献
26.
Conclusions: the Future Relevance of Medical Geography in the Third World This article has deliberately ranged widely and suggested various research themes to which medical geographers interested in health and development might turn their attention. The International Geographical Union Commission on Health and Development established in 1988 suggested a research agenda which includes many of them (see IGU Commission on Health and Development, Circular Letter No. 1 published in GeoJournal 17, 4, 659–660 (1988)). The achievement of even part of such an agenda will call for close international collaboration in research amongst medical geographers and allied disciplines.Increasingly, medical geographers are gaining applied experience in health and health care in the developing world. They are obtaining breadth and depth of knowledge and are now, for example, cogniscant of financial matters such as those involved in the cost explosion in health care worlwide which has particularly sinister implications for the health of Third World countries (Josephg and Phillips 1984). They, too, are now increasingly comfortable in dealing with epidemiological and demographic data. Geographers now no longer focus solely on phenomena such as distance decay or environments for disease. They are aware that human resources, intelligence, aspirations, attitudes and finance are all potent variables influencing successful health care and health in populations.In the future, therefore, the wide-ranging ambit of medical geography will increasingly become relevant to health and health care research in the Third World. Contributions of value will emerge both from those geographers adopting more socio-political stances and those adopting a more empiricist approach. However, it is the holistic nature of geography, with its wide academic links, and the courage of geographers to research in new topics and gain sound understanding of them which will increasingly be recognized. The days of extempore contributions to political, policy and practical debates on health and development are now largely past. Well researched, solid and sound medical geography contributions will, it is hoped, forge ahead. 相似文献
27.
Brian L. Phillips R. James Kirkpatrick Andrew Putnis 《Physics and Chemistry of Minerals》1989,16(6):591-598
High-resolution 27Al MAS NMR spectra of natural leucite recorded at H
0=11.7T contain three resolvable resonances at 27Al δ
i = 69.2, 64.7, and 61.0±0.5 ppm. These three resonances are assigned to the three inequivalent framework positions of leucite:
T3, T2, and T1, respectively. Fitting the observed spectra yields a Si,Al distribution for leucite in which approximately
one-half of the Al is in T1 and one-quarter in each of T2 and T3. This Si,Al distribution differs substantially from those
obtained by previous workers using 29Si NMR spectroscopy and X-ray diffraction. New 29Si NMR spectra and revision of previously reported 29Si NMR peak assignments, however, make the 27Al and 29Si NMR results consistent. The 27Al δ
i correlate linearly with the mean T-O-T′ bond angles of the average structure, which allows the peak assignments to be made.
However, this correlation lies distinctly toward higher frequency and larger bond angles than correlations for Si,Al ordered
aluminosilicates, suggesting that the mean T(Al)-O-T′(Si) bond angle for each site in leucite is smaller than the mean bond
angle of the average structure, which is averaged over T(Al)-O-T′(Si) and T(Si)-OT′(Si,Al) angles. 相似文献
28.
Experimental effects of water stress on semi-arid Karoo seedlings: implications for field seedling survivorship 总被引:1,自引:0,他引:1
Very little is known about seedling establishment in the semi-arid Karoo of southern Africa. In a greenhouse study, we investigated the responses of seedlings of three shrub species to water stress by withholding water at different stages of seedling development. Mortality of the two Asteraceous species, Pteronia pallens and Osteospermum sinuatum was more rapid where seedlings were provided with water for longer periods before being subjected to water stress. Hardened seedlings, exposed to water stress at an earlier stage, survived the longest. These seedlings were the smallest with respect to root and shoot mass. Seedlings of the leaf succulent Ruschia spinosa were extremely hardy and after 400 days without water, approximately 80% of the seedlings were still alive. The last P. pallens seedling died 160 days after water had been withheld. Osteospermum sinuatum seedlings were the least tolerant to water stress and 100% mortality occurred within 120 days. These results are discussed in terms of microhabitat preferences of the seedlings in field situations. 相似文献
29.
This paper brings anthropological, sociological and geographical perspectives to bear on the problem of farm sustainability and, in particular, the legitimation of sustainable farm practices. It attempts to lay some theoretical foundations for explanation of the adoption of farming practices which may, or may not, promote sustainability. A brief survey of the literature surrounding these issues finds many of the current theoretical perspectives incapable of fully accounting for the complexity of farming practice. Reductionist decision/rational‐action models, in particular, are found wanting for their lack of both cultural consistency and social/spatial specificity. Instead, this paper promotes a generative structuralist approach directed towards an analysis of social and economic practice in lived space; that is, firmly anchored in long‐term ethnographic research. 相似文献
30.
Improved regional and interregional stratigraphic correlations of Pennsylvanian strata permit comparisons of vegetational changes in Euramerican coal swamps. The coal-swamp vegetation is known directly from in situ coal-ball peat deposits from more than 65 coals in the United States and Europe. Interpretations of coal-swamp floras on the basis of coal-ball peat studies are extended to broader regional and stratigraphic patterns by use of coal palynology. Objectives of the quantitative analyses of the vegetation in relation to coal are to determine the botanical constituents at the peat stage and their environmental implications for plant growth and peat accumulation. Morphological and paleoecological analyses provide a basis for deducing freshwater regimes of coal swamps.Changes in composition of Pennsylvanian coal-swamp vegetation are quire similar from one paralic coal region to another and show synchrony that is attributable to climate. Paleobotany and paleogeography of the Euramerican province indicate a moist tropical paleoclimate. Rainfall, runoff and evapotranspiration were the variable climatic controls in the distribution of coal-swamp vegetation, peat accumulation and coal resources. In relative terms of climatic wetness the Pennsylvanian Period is divisible into five intervals, which include two relatively drier intervals that developed during the Lower-Middle and Middle-Upper Pennsylvanian transitions. The climate during Early Pennsylvanian time was moderately wet and the median in moisture availability. Early Middle Pennsylvanian was drier, probably seasonally dry-wet; late Middle Pennsylvanian was the wettest in the Midcontinent; early Late Pennsylvanian was the driest; and late Late Pennsylvanian was probably the wettest in the Dunkard Basin. The five climatic intervals represent a general means of dividing coal resources within each region into groups with similar botanical constituents and environments of peat accumulation. Regional differences in basinal geology and climate were significant variables, but the synchronous control of paleoclimate was of primary importance. 相似文献