Sky view and weathercontrols on nocturnal surface moisture deposition on grass at urban sites
British Columbia ; Canada ; Cloud ; Soil ; Soil moisture ; Urban climate ; Vancouver ; Weather type ; Wind
In this paper, sky view and weathercontrols on nocturnal surface moisture deposition are explored using data collected in Vancouver, British Columbia, Canada, during the summers of 1993 and 1996. The study focuses on residential (suburban) areas
: residential lawns and grassed parks. Moisture accumulation at open sites was strongly controlled by weather conditions. Correlation was seen between moisture accumulation and wind and cloud conditions expressed as the semi-empirical weather factor.
Lithological evidence for the evolution of weathered mantles in Uganda by tectonically controlled cycles of deep weathering and stripping
Geochemistry ; Lithology ; Mineralogy ; Model ; Stratigraphy ; Tectonics ; Uganda ; Vertical movement ; Weathering
In this study, a tectonic model of landscape evolution recently developed for Uganda, was tested by detailed study of the weathered mantle. The study involved an analysis of weathered-mantle stratigraphy, texture, mineralogy and elemental
geochemistry, and was conducted in 2 catchments of central and southwestern Uganda which feature contrasting geomorphic processes (deep weathering and stripping) and different (post mid-Miocene) evolutionary histories.
Parent material controlled subsoil weathering in a chronosequence, the Allier terraces, Limagne rift valley, France
Allier ; Chronosequence ; Fluvial terrace ; France ; Geochemistry ; Lithology ; Massif Central ; Model ; Weathering
The goal of this paper is to determine and quantify the effect of the original sediment composition on the actual terrace sand composition in the Allier chronosequence. Further it is tried to determine the control of parent material on subsoil
weathering in a chronosequence by means of process modelling with a theoretical model.
A model for the evolution of weathered landsurfaces in Uganda is developed using available geotectonic, climatic, sedimentological and chronological data. The model demonstrates the pivotal role of tectonic uplift in inducing cycles of stripping
, and tectonic quiescence for cycles of deep weathering. Development of the Ugandan landscape is traced back to the Permian.
Regolith behaviour and physical weathering of clayey mudrock as dependent on seasonal weather conditions in a badland area at Vallcebre, Eastern Pyrenees
This work describes some properties of the regolith through the seasons, together with the known factors that control physical weathering (humidity and temperature oscillations), and some of the hydrological and erosive controls effected
Arid area ; Insolation ; Jordan ; Lithology ; Sandstone ; Statistics ; Threshold ; Weathering
The primary focus of this investigation was to examine the various mechanisms and rates responsible for sandstone weathering in an arid climate by controlling lithology, time, and the initial surface condition. However, the possible existence
of thresholds warranted further analysis since this was the first case in which thresholds were recognized in a weathering-related study.
Climatic and morphological control of rare earth element distribution in weathering mantles on alkaline rocks
Brazil ; Drainage ; Geochemistry ; Mineralogy ; Palaeo-environment ; Palaeoclimate ; Tropical zone ; Weathering
This contribution focuses on the interpretation of REE patterns on a regional scale by comparing profiles from varios climatic zones and morphological positions. Under consideration of polyphase and polygenetic weathering processes, present REE
distribution patterns are related to different phases of landscape and climatic evolution in SE-Bahia State, Brazil. Finally the use of REE patterns as tools for the reconstruction of landscape evolution and weathering history is discussed.
-controlled chemical weathering and physical erosion history during the last 190,000 yr in the eastern Tibetan Plateau and the Mekong Basin. Discussion of the results.
Variable weathering response in sandstone : factors controlling decay sequences
Chemical erosion ; Experimentation ; Freeze-thaw cycle ; Northern Ireland ; Permeability ; Salt ; Sandstone ; United Kingdom ; Weathering
Differences in weathering response characteristics of fine- and coarse-grained Stanton Moor sandstone samples were assessed in a laboratory weathering simulation experiment using a variable combination of salt weathering and freeze/thaw cycles. Data
and mineralogical differences between samples of the same stone type can have a significant influence on weathering behaviour.
Weathering of paleozoic marbles in the Independence Hills and Patriot Hills, Ellsworth Mountains, Antarctica
Antarctica ; Cold area ; Freeze-thaw cycle ; Frost action ; Mountain ; Polar region ; Soil moisture ; Weathering
This study clarifies the importance of frost action on rock weathering in continental polar climates. A field site was selected in the Ellsworth Mountains of western Antarctica. North- and south-facing walls of the bedrock showed the same shattering
rate in the summer of 1992-1993. Frost shattering of rocks is controlled by surface temperature, moisture, and the physical properties of the rock. The most important control on frost shattering in this area was moisture availability, given the same
are comparable in the two regions. The gradients of chemical activities in the micro-environment (surfaces of grains, pores, microfissures) seem to be the controlling factors of weathering.
Various stages of tropical weathering are described using a number of examples of red soil formation derived from rif basalts in Burundi and laterite bauxites from plateau basalts of South Vietnam. The phenomena of decomposition of primary minerals
Physical deterioration of sedimentary rocks subjected to experimental freeze-thaw weathering
Building materials ; Experimentation ; Freeze-thaw cycle ; Geotechnics ; Lithology ; Sandstone ; Sedimentary ; Sedimentary rock ; Weathering
This paper addresses the influence of pre-existing flaws on the durability of ten sedimentary rocks under experimental freeze-thaw weathering. Results suggest that the presence or absence of rock flaws alone does not control deterioration mode
, but rather that it is the coupled relationship between these flaws, and rock strength and textural properties which exerts greatest influence. This work also has practical implications for the study of landform development due to weathering
Assessing volumetric strains and mass balance relationships resulting from biotite-controlledweathering: Implications for the isovolumetric weathering of the Boulder Creek Granodiorite, Boulder County, Colorado, USA
Chemical erosion ; Colorado ; Geochemistry ; Mineralogy ; United States of America ; Weathering
strains on the order of 7.6%–8.5% and 7.9%–8.2% respectively. They show that dilation is likely due to the alteration of biotite to vermiculite during the early stages of weathering, and is associated with an expansion normal to the {001} cleavage of ~ 40
Mineralogical and structural features control the weathering processes and landform development of 2 different crystalline stocks in the Iberian Massif : the Santa Elena and Linares stocks. Mineralogical and geochemical evidence indicate the Santa
Elena materials are more intensely weathered. High fracturation and high Ca-richer plagioclase contents are key factors producing the pervasive Santa Elena stock weathering. Fluvial erosion removed the alteration products in incised tectonically
controlled streams resulting in boulder accumulation.
The roles of salt (sodium nitrate) and fog in weathering : a laboratory simulation of conditions in the northern Atacam Desert, Chile
Arid area ; Chile ; Desert ; Experimentation ; Fog ; Salt ; Simulation ; Weathering
The AA. investigate interactions within a hyper-arid and hyper-saline weathering environment based on conditions observed in the Atacama Desert. The experimental design produced a matrix of 18 different weathering environments with 6 levels of salt
availability and 3 levels of fog precipitation. The experiment took place over an 11-week period. Collectively, the results indicate that fog appears to control the rate of breakdown and that salt availability controls the timing of the response. The style
of breakdown was similar, irrespective of the fog and salt levels. The morphological observations provide an experimental example of the role of inheritance in weathering processes.
Chemical erosion ; Concept ; Geomorphology ; Peneplain ; Tropical zone ; Weathering
Concepts in tropical geomorphology are briefly outlined together with their basic observations and arguments-climatically controlled exogenic forces are most active due to the high temperatures and humidity, resulting in intensive weathering
. The A. concludes there is a strong plea for the morphogenetic approach which includes former and recent processes of weathering and denudation.
Rill systems on mudrock and sandstone in Alberta badlands were studied to examine progressive changes in material properties as smectic-rich mudrocks and sandstones undergo weathering, and the impact of seasonal changes in precipitation patterns
. Three plots with well developed rill systems on each unit were examined in May 2001 and 2003. In controlled laboratory conditions, depending on moisture input, different crust types developed on materials after 10 wetting-drying cycles.
mountain catchment, and the AA. focussed on the continuous observation of a number of physical parameters that control regolith development and weathering processes.