نتایج جستجو برای: ultramafic bedrock

تعداد نتایج: 4457  

2008
F. Brett Denny W. John Nelson Joseph A. Devera

2005
D. J. MILTON F. A. MACDONALD

Goat Paddock in northern Western Australia is a *5 km-diameter impact crater of Eocene age excavated in gently dipping Proterozoic sandstones. Roughly radial gorges formed by post-impact erosion provide cross-sectional views of the wall and rim zone. The predominant structural theme is one of synclinal rim folding with broad zones in which bedrock strata were deformed by impact to steep, vertic...

2012
David S. McKay Grant Heiken Abhijit Basu George Blanford Steven Simon Robert Reedy Bevan M. French James Papike

Regolith is a terrestrial term, also used for the Moon. It has been defined as " a general term for the layer or mantle of fragmental and unconsolidated rock material, whether residual or transported and of highly varied character, that nearly everywhere forms the surface of the land and overlies or covers bedrock. It includes rock debris of all kinds, [including] volcanic ash. .. " (Bates and ...

2002
David R. Montgomery William E. Dietrich John T. Heffner

[1] Experimental observations comparing two steep unchanneled valleys in the Oregon Coast Range, one intensively instrumented (CB1) and the other monitored for runoff but which produced a debris flow (CB2), shed light on the mechanisms of shallow flow in bedrock, its interaction with the vadose zone, and its role in generating landslides. Previous work at CB1 led to the proposal that during sto...

2017
Oliver W. Moore Heather L. Buss Sophie M. Green Man Liu Zhaoliang Song

Soil degradation, including rocky desertification, of the karst regions in China is severe. Karst landscapes are especially sensitive to soil degradation as carbonate rocks are nutrient-poor and easily eroded. Understanding the balance between soil formation and soil erosion is critical for long-term soil sustainability, yet little is known about the initial soil forming processes on karst terr...

2010
Brian A. Clarke Douglas W. Burbank

a r t i c l e i n f o Keywords: bedrock fractures threshold slopes landslides landscape evolution erosion Bedrock fracturing and rock strength are widely believed to influence landscape morphology and erosional resistance. Yet, understanding of the quantitative relationship between rock-mass strength and landscape evolution remains limited. Here we present a new application of seismic refractio...

Journal: :Science 2015
J St Clair S Moon W S Holbrook J T Perron C S Riebe S J Martel B Carr C Harman K Singha D deB Richter

Bedrock fracture systems facilitate weathering, allowing fresh mineral surfaces to interact with corrosive waters and biota from Earth's surface, while simultaneously promoting drainage of chemically equilibrated fluids. We show that topographic perturbations to regional stress fields explain bedrock fracture distributions, as revealed by seismic velocity and electrical resistivity surveys from...

2015
G. De Vicente

An understanding of rates and mechanisms of incision and knickpoint retreat in bedrock rivers is fundamental to perceptions of landscape response to external drivers, yet only sparse field data are available. Here we present eye witness accounts and quantitative surveys of rapid, amphitheatre-headed gorge formation in unweathered granite from the overtopping of a rock-cut dam spillway by small-...

Journal: :ISPRS Int. J. Geo-Information 2014
John G. Van Hoesen

Many state and national geological surveys produce map products from surficial and bedrock geologic maps as a value-added deliverable for a variety of stakeholders. Improvements in powerful geostatistical exploratory tools and robust three-dimensional capabilities within geographic information systems (GIS) can facilitate the production of derivative products. In addition to providing access to...

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