نتایج جستجو برای: fluvial

تعداد نتایج: 4448  

2007
Oliver Korup Fritz Schlunegger

[1] The formation of inner gorges cut into bedrock has been explained as relief rejuvenation by fluvial incision in response to rapid base level drop, repeated glaciations, frequent pore pressure–driven landsliding focused at hillslope toes, or catastrophic outburst flows from natural dam failures. Prominent inner gorges occur in soft Mesozoic Bündner schist and lower Tertiary flysch units of t...

2003
Jeffrey E. Richey

As the main pathway for the ultimate preservation of terrigenous production in modern environments, the transfer of organic matter from the land to the oceans via fluvial systems is a key link in the global carbon cycle (Ittekot and Haake 1990; Degens et al. 1991; Hedges et al 1992). Hence, the “role” of rivers in the global carbon cycle is most typically expressed as the fluvial export of tota...

2003
Robert A. Craddock Marsha A. Presley

Introduction: In the search for life on Mars, investigating fluvial deposits will be a high priority for future landers. Although there is abundant evidence that fluvial processes worked with great intensity in the past (e.g., outflow channels, valley networks, and modified impact craters), aeolian processes dominate under the current environmental conditions. In fact there is evidence that ext...

2017
Christopher R. Fielding

Fluvial strata dominated internally by sedimentary structures of interpreted upper flow regime origin are moderately common in the rock record, yet their abundance is not appreciated and many examples may go unnoticed. A spectrum of sedimentary structures is recognised, all of which occur over a wide range of scale: 1. cross-bedding with humpback, sigmoidal and ultimately low-angle cross-sectio...

2006
Simon H. Brocklehurst Kelin X. Whipple

The relative rates of erosion by rivers and glaciers, and the topographic effects of these two different styles of erosion, remain outstanding problems in geomorphology. We use a quantitative description of local fluvial landscapes to estimate how glaciated landscapes might look now had glaciers not developed. This indicates the landscape modification attributable to glacial erosion. We present...

2016
David K. Weiss James W. Head

Fluvial features present around impact craters on Mars can offer insight into the ancient martian climate and its relationship to the impact cratering process. The widespread spatial and temporal distribution of surface ice on Mars suggests that the interaction between impact cratering and surface ice could have been a relatively frequent occurrence. We explore the thermal and melting effects o...

2005
Rossman P. Irwin Alan D. Howard Robert A. Craddock Jeffrey M. Moore

[1] To explain the much higher denudation rates and valley network development on early Mars (> 3.6 Gyr ago), most investigators have invoked either steady state warm/wet (Earthlike) or cold/dry (modern Mars) end-member paleoclimates. Here we discuss evidence that highland gradation was prolonged, but generally slow and possibly ephemeral during the Noachian Period, and that the immature valley...

2006
M. K. Clark L. H. Royden K. X. Whipple B. C. Burchfiel X. Zhang W. Tang

[1] Field work and topography analysis show that remnant, local areas of a low-relief landscape or erosion surfaces are geographically continuous across the southeastern Tibetan Plateau margin. We correlate these remnant surfaces as a paleolandscape that formed at low elevation. Remnants of this paleolandscape are preserved because incision of the fluvial system has been largely limited to majo...

1998
Lewis A. Owen Milap C. Sharma

The development of paraglacial fans, studied in the upper Bhagirathi valley, Garhwal Himalaya, northern India, relates to the retreat of the Gangotri Glacier over the last 200 years. These fans demonstrate the speed by which mass movement and fluvial processes may lead to the modification and readjustment of the Himalayan landscapes during deglaciation. The paraglacial fans in this region grew ...

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