An experimental study of the Fe-Mn exchange between garnet and ilmenite

The exchange equilibrium

THE OTTAWA CONGRESS

The International Society for Photogrammetry held the XIIth International Congress at Ottawa during July and August 1972. The authors comprised a panel which engaged in discussion upon the Congress at a meeting of the Photogrammetric Society on 17th October, 1972.     

Time variation of martian regional contrasts

Observations of contrast changes in blue light on Mars in 1969 and 1971 are presented. Seasonal effects evidently can be evaluated from these data, although nonseasonal effects are also present. A diurnal variation is noted for certain features during both apparitions. This variation cannot be fully accounted for without considering meteorological effects. An example of a contrast reversal in ultraviolet light is presented. The suggestion is made that during the Martian season covered herein, variability of the bright areas controlled the apparent contrasts observed.     

SPACE RESECTION WITHOUT INTERIOR ORIENTATION

In this paper projective methods are used to resect the vertex of a picture when the interior orientation elements are unknown. In the course of the work the projective theory of photography is taken beyond its most elementary stages.     

UBV photometry of the Galilean satellites

UBV observations of the Galilean satellites made at Lowell Observatory and Cerro Tololo Inter-American Observatory during 1973 and 1974 are reported. The dependence of brightness on solar phase angle for various faces of each satellite is determined. Significant differences in this dependence are found between different faces of the same satellite, between satellites, and between the present results and those of previous investigators. Rotational light and color-index curves are presented for the satellites and compared with earlier work. An apparent secular brightening of all four satellites between 1973 and 1974 is discussed.     

Sweeping through a second order resonance

The adiabatic invariant theory and its extension to the case of separatrix crossing have been instrumental in setting up simple models describing the effects of the passage through a first order resonance forced by small non conservative forces. These models have been helpful in understanding the processes of capture into resonance and of formation of gaps at resonances. Second order resonances (3/1 or 5/3 ...) have not been so thoroughly investigated and present some special features. We shall show how to disencumber first the problem from its secular term and how to modelize the mixed resonance term involving the sum of the resonant angles. A modelization of the two single satellite resonant terms has already been proposed by Lemaître and Borderies and Goldreich. We shall then assemble those three simple models to show the effect of a passage through the resonance under the assumption that the natural precession rates are large enough for the three individual resonances to be sufficiently separated.     

Significance of Landscape Age,Uplift, and Weathering Rates to Ecosystem Development

The combined roles of chemical and physical weathering have profound effects on the development of terrestrial ecosystems. Landscapes which are tectonically active are rapidly denudated and continually produce nutrient solutes from fresh bedrock. The chemical weathering yields are related to climate, but also to geologic factors such as uplift rates. Long-term nutrient production and the phase of ecological development are closely related to geological setting. Until recently, this relationship has not been seriously considered by ecologists. Our analysis of existing information suggests, however, not only that the nature and type of geologic processes provide significant insights into landscape, but also to ecological development. In this paper, we describe the impact of geologic uplift on the long term generation of soluble nutrients from bedrock by evaluating long-term data from a number of forested sites and comparing it to newly collected data from Taiwan, an area undergoing rapid tectonic uplift.     

Heat as a ground water tracer

Heat carried by ground water serves as a tracer to identify surface water infiltration, flow through fractures, and flow patterns in ground water basins. Temperature measurements can be analyzed for recharge and discharge rates, the effects of surface warming, interchange with surface water, hydraulic conductivity of streambed sediments, and basin-scale permeability. Temperature data are also used in formal solutions of the inverse problem to estimate ground water flow and hydraulic conductivity. The fundamentals of using heat as a ground water tracer were published in the 1960s, but recent work has significantly expanded the application to a variety of hydrogeological settings. In recent work, temperature is used to delineate flows in the hyporheic zone, estimate submarine ground water discharge and depth to the salt-water interface, and in parameter estimation with coupled ground water and heat-flow models. While short reviews of selected work on heat as a ground water tracer can be found in a number of research papers, there is no critical synthesis of the larger body of work found in the hydrogeological literature. The purpose of this review paper is to fill that void and to show that ground water temperature data and associated analytical tools are currently underused and have not yet realized their full potential.