Painting Yosemite Valley : a Case study of rockcoatings encountered at Half Dome
This paper identifies the types of rockcoatings found on Half Dome, in Yosemite Valley, assesses the hypothesis that the rockcoatings of Yosemite are consistent with the landscape geochemical model of rockcoating formation, and considers
the relevance of equifinality. Eight types of rockcoatings were identified: case-hardened surfaces, heavy metal skins, iron films, lithobiontic coatings, oxalate crusts, manganiferous rock varnish, silica glaze, and anthropogenic pigments. The landscape
geochemical model of rockcoating formation and the concept of equifinality both proved useful in this investigation.
Distribution and chemical composition of microcolonial fungi and rockcoatings from arid Australia
In this study, microcolonial fungi were examined on rockcoatings found at a range of sites in arid Australia. Comparisons were made between the elemental composition of various rockcoatings and the microcolonial fungi found on them
, and the possible role of microcolonial fungi in relation to coating development or destruction was examined.
Formation of silica glaze rockcoatings through water vapor interactions
Arid area ; Basalt ; Desert ; Geochemistry ; Hawaii ; Mars planet ; Moisture ; Rockcoatings ; Rock varnish ; Silica ; Subtropical zone ; Volcano ; Water vapor ; Weathering
silica glaze and may be an important factor in explaining why silica glaze is the dominant rockcoating in humid warm drylands. In addition to adding a new dimension to the formation of terrestrial rockcoatings, these findings may have importance
A two decade-long laboratory experiment tested importance of high water vapor content in silica glaze formation. Twenty years of exposing basalt rock chips to 80% and 90% levels of relative humidity revealed that water vapor alone can generate
in interpreting any coatings of amorphous silica found on Mars.
Fracture surfaces of red mudstones (overbank deposits within the Kuzgun Formation of Late Miocene-Tortonian — age) are coated by thin black colored manganese oxide beneath a thin soil cover in the Mersin area of southern Turkey. These manganese
oxide coatings have been investigated by a range of analytical techniques, including X-ray diffraction (XRD), infrared-spectral (IR), differential thermal analysis–thermal gravimetric (DTA–TG), scanning electron microscopy and energy-dispersive X-ray
(SEM–EDX) analyses. The coatings consist predominantly of Ca-buserite and organic matter. The results suggest a pedogenic origin for the coatings.
Rapid formation of rock varnish and other rockcoatings on slag deposits near Fontana, California
Manganiferous rock varnish, silica glaze and iron skins have formed on 20- to 40-year-old slag piles near Fontana, southern California. Rapid rock-varnish formation is associated with an unidentified cocci bacterium that grows rapidly in culturing
Uncertainties in the radiocarbon dating of organics associated with rock varnish : a plea for caution
C 14 dating ; Dating ; Diagenesis ; Geochemistry ; Methodology ; Organic materials ; Rock ; Weathering
The conclusion of the A. is that the interpretation of radiocarbon ages associated with rock varnish is unclear, and there may be similar problems associated with other rockcoatings. To obtain reliable ages in the future, the effort must be based
on a careful characterization of different types of organic matter associated with rock varnish. In addition, the ages of different types of organics must be measured where there are independent age controls, and in blind tests.
Manganese accumulation in rock varnish on a desert piedmont, Mojave Desert, California, and application to evaluating varnish development
This paper presents an initial attempt to quantify the progressive development of varnish coats over time by measuring the amount of Mn accumulated in varnish collected from geomorphic surfaces of different ages. The data demonstrate that rock
for samples like rockcoatings with heterogeneous density and abundant porosity. A new technique involving multiangle ion thinning and in situ plan-view lift-out facilitated a scanning transmission electron microscopy study of rock varnish from Death Valley
The cross-sectional texture of rock varnish varies considerably with the scale of analysis and technique used to image a sample. One key to nanoscale analysis involves focused ion beam (FIB) techniques, but FIB preparation remains challenging
Télédétection d'une roche granitoïde non affleurante à travers une anomalie thermique du couvert forestier (Forêt de Coat-en-Noz, Bretagne)
Bretagne ; Coat an Noz, forêt ; Contrôle géologique ; Couvert forestier ; Cristallin ; Forêt ; France ; Généralités sur la géographie ; Roche granitoïde ; Thermographie ; Télédétection
Les thermographies aériennes réalisées sur la Forêt de Coat-en-Noz mettent en évidence une anomalie rectiligne de la température de radiance des hêtres qui se corrèle géométriquement avec une roche granitoïde non affleurante. Il semble que des
Calcrete-coated remnants of landslide debris and alluvial deposits are exposed along the hillslopes of the Soreq drainage, Judea Hills, Israel. These remnants indicate that a transition from landslide-dominated terrain to dissolution-controlled
by thick calcrete crusts overlying Upper Cretaceous marine carbonate rocks. Using TT-OSL dating of aeolian quartz grains incorporated in the calcrete which cements an ancient landslide deposit, it is concluded on the incision that invoked high frequency
Suites of quartz sand samples from 7 erg deposits of the north-central Saharan desert were analyzed by scanning electron microscopy (SEM) to determine if microtextures and coating chemistry could elucidate information on transport and climatic
histories. To determine the effect of local aeolian processes, the AA. concentrated on the interpretation of fractures and abrasion microtextures on quartz grains. To elucidate paleoenvironmental histories they sought to determine the chemistry of coatings
The landforms lie at a low altitude in the south-western part of the Sahara and in the Sahel. Some old lateritic duricrusts are still extent on plateaus, especially on the Tagent in central Mauritania. The Continental terminal deposits are coated
. In spite of similar geographical locations, the coatings are not the same in these two morphological regions which lie at present in the arid or semi-arid tropical zone. It seems that these differences are due to a movement of the african plate
. This is the main volcanic structure of peninsula and phreatomagmatic activity probably began here. The lapilli and coarse ashes in the pyroclastites are generally mud-coated, accretionary lapilli are common, and the tuffs are frequently light brownish, suggesting