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Showing 1 to 16 of 16 for “"knickpoint"”.
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Knickpoint analysis of streams in North Dakota, South Dakota, and Nebraska
<p>Analysis of stream profiles, seismic reflection studies, engineering studies, and historical earthquakes indicates uplift in south-central South Dakota and north-central Nebraska over the last 5-10 ma. The purpose of this study was to determine if this uplift could be detected by constructing …
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New incision rates on the Colorado River system based on cosmogenic burial dating of terraces : implications for a transient knickpoint at Lees Ferry and differential uplift of the Rocky Mountains
… profiles in both rivers are evident by numerous knickpoints and convexities. By compiling existing age constraints and applying cosmogenic burial dating techniques to previously undated bedrock strath terraces, we determine spatial and temporal patterns of incision and profile evolution over the …
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Investigating the Effects of Lithology on Landscape Evolution Processes across Scales
… setting fluvial bedrock erodibility by comparing knickpoint and non-knickpoint bedrock, which correspond to end-member erodibility cases, and assess how lithology impacts knickpoint expression. Detailed field surveys of 21 lithologic knickpoints, surrounding non-knickpoint reaches, and …
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Quaternary incision history of the Black Canyon of the Gunnison, Colorado
… longitudinal river profile exhibits a prominent knickpoint within the Black Canyon. In the last 640ka, average bedrock incision rates surrounding the knickpoint are unbalanced and vary from 130-150 m/Ma (downstream) to 470-600+ m/Ma (within) to 90-95 m/Ma (upstream), necessitating knickpoint …
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Understanding uplift of the Ethiopian Plateau from longitudinal profile analysis of the Blue Nile drainage system
… longitudinal rive-profile forms and parameters (knickpoint and normalized steepness-index <em>k<sub>sn</sub></em>) of the Blue Nile tributaries to tease out regional tectonic signals.</p> <p>244 knickpoints were examined in the tributaries, majority (>80%) of which are unassociated with lithology …
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Lithologic Controls on Bedrock Channel Morphology in the Buffalo River Basin
… age limestone, typically correspond to knickpoints arrested at the upper contact. Field and laboratory analysis suggest that limestone dissolution may be an important mechanism for knickpoint initiation in the Boone Formation.</p>
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The transient response of bedrock river networks to sudden base level fall
… in the channel profile, defined here as a knickpoint. In this thesis, theoretical, numerical, and field-based research techniques are utilized to study the initiation and distribution of knickpoints within fluvial networks. Field observations are derived from the Waipaoa River on the North …
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Timing and pattern of valley excavation, Le Sueur River, south-central Minnesota, USA
… incision on Minnesota River tributaries as knickpoints propagated upstream from the main stem Minnesota River. As the knickpoint moved up the Le Sueur River, hundreds of terrace surfaces were formed. These terraces are strath terraces carved into glacial tills, with alluvial deposits …
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Mechanisms governing avulsions in transient landscapes : analysis of the May 2006 Suncook River avulsion in Epsom, New Hampshire
… can also contribute to avulsions by allowing a knickpoint to migrate quickly upstream and create a channel with a more favorable slope during a single flood. Based on Slingerland and Smith's (2004) model, we also propose that a low water-surface slope in the parent channel could be a direct …
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Evolution of transient topography on passive margins: A study of landscape disequilibrium in the southern Appalachian Mountains
… undocumented relict fluvial gravels and knickpoint location to confirm the role of drainage rearrangement in producing local base level drop and subsequent basin-scale transient incision in the southern Appalachians. This process is fundamentally driven by the high potential energy of …
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Lithological and climatic controls on fluvial landscape evolution of a post-orogenic dryland mountain belt
… terrace incision nucleates and propagates as a knickpoint connecting reaches of the river at a 105 yr timescale over ~ 20 km river length. In addition, further than 20 km upstream independent nucleation of river incision occurred, asynchronous from the first at a 104 yr timescale. Weak bedrock …
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Modelling the Holocene evolution of coastal gullies on the Isle of Wight
… gully extent) and headwards incision caused by knickpoint migration (which increases gully extent). To inform the choice and parameterisation of the numerical model used in this research an empirical-conceptual model of gully evolution was initially developed. To provide a long-term context for …
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Origin and stratigraphy of Holocene sediments, Souris and Des Lacs glacial-lake spillways, north-central North Dakota
… last glacial-lake outburst, a headward-migrating knickpoint developed in the Souris Valley. This was caused by downcutting of the valley bottom while the flood was discharging into Glacial Lake Souris. After the flood subsided, an aggrading, meandering Souris River occupied the valley. Initially, …
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EPISODIC UPLIFT OF THE ROCKY MOUNTAINS: EVIDENCE FROM U-PB DETRITAL ZIRCON GEOCHRONOLOGY AND LOW-TEMPERATURE THERMOCHRONOLOGY WITH A CHAPTER ON USING MOBILE TECHNOLOGY FOR GEOSCIENCE EDUCATION
… rates over the last 0.64 Ma surrounding the knickpoint vary from 150 m/Ma (downstream), to 400-550 m/Ma (within), to 90-95 m/Ma (upstream), suggesting it is a transient feature. Lava Creek B ash constrains strath terraces along a paleo-profile of the river. Within the paleo-Bostwick River …
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From phantom blocks to denudational noise
… denudation rates across the morphological knickpoint that marks the transition from the Transhimalayan ranges to the Tibetan Plateau. This trend is corroborated by independent bulk petrographic and heavy mineral analysis of the same samples. -> From the observation that tributary-derived …