Journal ArticleDOI
Landscape response to tectonic forcing: Digital elevation model analysis of stream profiles in the Mendocino triple junction region, northern California
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In this article, the authors evaluate and calibrate the shear stress (or similar unit stream-power) bedrock-incision model by studying stream profiles in a tectonically active mountain range.Abstract:
The topographic evolution of orogens is fundamentally dictated by rates and patterns of bedrock-channel incision. Quantitative field assessments of process-based laws are needed to accurately describe landscape uplift and denudation in response to tectonics and climate. We evaluate and calibrate the shear stress (or similar unit stream-power) bedrock-incision model by studying stream profiles in a tectonically active mountain range. Previous work on emergent marine terraces in the Mendocino triple junction region of northern California provides spatial and temporal control on rock-uplift rates. Digital elevation models and field data are used to quantify differences in landscape morphology associated with along-strike northwest to southeast changes in tectonic and climatic conditions. Analysis of longitudinal profiles supports the hypothesis that the study-area channels are in equilibrium with current uplift and climatic conditions, consistent with theoretical calculations of system response time based on the shear-stress model. Within uncertainty, the profile concavity (𝛉) of the trunk streams is constant throughout the study area (𝛉 ≈ 0.43), as predicted by the model. Channel steepness correlates with uplift rate. These data help constrain the two key unknown model parameters, the coefficient of erosion ( K ) and the exponent associated with channel gradient ( n ). This analysis shows that K cannot be treated as a constant throughout the study area, despite generally homogeneous substrate properties. For a reasonable range of slope-exponent values ( n ), best-fit values of K are positively correlated with uplift rate. This correlation has important implications for landscape-evolution models and likely reflects dynamic adjustment of K to tectonic changes, due to variations in orographic precipitation, and perhaps channel width, sediment load, and frequency of debris flows. The apparent variation in K makes a unique value of n impossible to constrain with present data.read more
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Book ChapterDOI
Tectonics from topography: Procedures, promise, and pitfalls
Cameron Wobus,Kelin X. Whipple,Eric Kirby,Noah P. Snyder,Joel P. L. Johnson,Katerina Spyropolou,Benjamin T. Crosby,Daniel Sheehan +7 more
TL;DR: In this article, a method for extracting topographic indices of longitudinal profi le shape and character from digital topographic data is described, which can then be used to delineate breaks in scaling that may be associated with tectonic boundaries.
Journal ArticleDOI
Bedrock rivers and the geomorphology of active orogens
TL;DR: The results of intense research in the past decade are reviewed in this article, with the aim of highlighting remaining unknowns and suggesting fruitful avenues for further research, including the role of climate-driven denudation in the evolution of orogens.
Journal ArticleDOI
Expression of active tectonics in erosional landscapes
TL;DR: In this paper, the authors provide an overview of the analysis and interpretation of channel profiles in erosional mountain ranges and show that existing data support theoretical expectations of positive, monotonic relationships between channel steepness index, a measure of channel gradient normalized for downstream increases in drainage area, and erosion rate at equilibrium, and that the transient response to perturbations away from equilibrium engenders specific spatial patterns in channel profiles that can be used to infer the forcing.
Journal ArticleDOI
Quantifying differential rock-uplift rates via stream profile analysis
TL;DR: In this paper, the authors developed a simple theory for the impact of spatially variable rock-uplift rate on the concavity of bedrock river profiles in the Siwalik Hills of central Nepal.
Journal ArticleDOI
Fluvial incision and tectonic uplift across the Himalayas of central Nepal
Jérôme Lavé,Jean Philippe Avouac +1 more
TL;DR: In this article, the pattern of fluvial incision across the Himalayas of central Nepal is estimated from the distribution of Holocene and Pleistocene terraces and from the geometry of modern channels along major rivers draining across the range.
References
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ReportDOI
Geologic map of the King Range and Chemise Mountain Instant Study Areas, Northern California
Journal ArticleDOI
Stevenson receives Hess Medal
TL;DR: In 1998, David J. Stevenson was presented with the Hess Medal at the AGU Spring Meeting Honors Ceremony, which was held on May 27, 1998, in Boston, Massachusetts.