Rational descriptive classification of duricrusts

The term duricrust appears to be extending itself to include calcareous, gypseous, and saline crusts, in addition to crusts composed dominantly of silica and/or of sesquioxides of iron and aluminium, with or without significant contents of dioxides of manganese or titanium. This latter group can be distinguished as duricrusts proper. Its nomenclature is highly confused, and its classification, in writings in the English language, defective. The relevant problems can be resolved, at least in considerable part, by the introduction, adaptation, and extension of modern terms current in tropical pedology, to give a descriptive classification free of genetic implications. When content of SiO₂, Al₂O₃, and Fe₂O₃ is used as a primary basis for the classification of duricrusts proper, plots on a ternary diagram justify the recognition of seven named types in the fersiallitic range

The Sydney duricrusts: their terminology and nomenclature

Two main duricrust types - laterites and ferricretes - and their underlying materials are mapped and described for the northern parts of the Sydney district, New South Wales. Laterites are by far the more widespread, being found both in the Wainamatta-Shales and in the Hawkesbury-Sandstone areas, particularly on the broad hilltops and interfiuves of the major divide between the three drainage systems - the north-flowing Hawkesbury-Broken Bay, the south-flowing Parramatta-Port Jackson and the east-flowing Pacific Ocean systems. The ferricretes occur mainly in the drier parts of the northwest, especially in the conglomeratic river gravels of the Maroota area. The two materials have similar profile characteristics but they are different in hand specimen, in textural and structural characteristics, and also in mineralogical composition. The duricrusts and their profiles have been widely destroyed and differentially truncated, so that their various zones and subzones are presently exposed at different places. These materials, especially in respect of laterites, are classified from field and laboratory evidence, according to their recognised, or assigned, position in the typical deep weathering profile. Names are assigned, depending on the area where the best examples were found

Martian surface properties

The objectives were: to characterize surficial geologic units through integration of Infrared Thermal Mapper (IRTM)-derived regolith properties with other existing remote sensing data; to determine the physical and spectral properties of volcanic units in the mid-latitudes of Mars through the synthesis of the highest resolution IRTM, radar, and imaging data available; and to identify and characterize aeolian terrains on Mars using physical surface characteristics determined from remote sensing data

Characterization of surficial units on Mars using Viking orbiter multispectral image and thermal data

Albedo and thermal property correlations of the topography of Mars were conducted with emphases upon the types and origins of materials exposed in the central equatorial region. This area displays a wide variation in color, albedo and thermal properties, and is relatively free of dust and haze. The physical, mineralogical and elemental characteristics of this area are discussed

Mars sample return: Site selection and sample acquisition study

Various vehicle and mission options were investigated for the continued exploration of Mars; the cost of a minimum sample return mission was estimated; options and concepts were synthesized into program possibilities; and recommendations for the next Mars mission were made to the Planetary Program office. Specific sites and all relevant spacecraft and ground-based data were studied in order to determine: (1) the adequacy of presently available data for identifying landing sities for a sample return mission that would assure the acquisition of material from the most important geologic provinces of Mars; (2) the degree of surface mobility required to assure sample acquisition for these sites; (3) techniques to be used in the selection and drilling of rock a samples; and (4) the degree of mobility required at the two Viking sites to acquire these samples

Atmospheric H2O and the search for Martian brines

Abundant martian brines would have important implication for current theories of volatile migration on Mars, since, although the presence of metastable brines is quite plausible, any brine in the reasonably near-surface should be completely depleted on a timescale short in relation to the age of Mars. It is important to determine whether brines exist in the martian subsurface, for the current paradigm for understanding martian volatile regime requires substantial alteration if they are found to exist. It is determined, however, that the prospect for detection of a subsurface brine via atmospheric water vapor measurements is marginal. Four reasons are given for this conclusion

Phytophthora root and collar rot in rehabilitated bauxite mines and the adjacent Eucalyptus marginata (Jarrah) forest of Western Australia

This study gives an overview of recent and current research activities that are being conducted in Western Australia on the biology, ecology and pathology of Phytophthora cinnamomi in rehabilitated bauxite mines and the adjacent jarrah (Eucalyptus marginata) forest. The work to date indicates that the biology of this pathogen does differ between rehabilitated mines and the adjacent jarrah forest

The Paleo-ocean of Mars

A Paleo-ocean on the northern plains of Mars is proposed. The hypothetical ocean would have formed very early in Mars' history, during the early period of rapid outgassing and cratering. As the ocean froze and receded, bursting of aquifers along the shoreline would create catastrophic flooding. Analysis of soil at the two Viking landing sites, both of which occur on the floor of the hypothetical ocean, is not inconsistent with an oceanic clay rich in water soluble salts