Evaluating escarpment evolution and bedrock erosion rates in the western Guadalupe Mountains, West Texas and New Mexico

Tranel, Lisa M.; Happel, Audrey

doi:10.1016/j.geomorph.2020.107335

Cited by 3 publications

(4 citation statements)

References 65 publications

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“…Our compilation includes localities across various tectonic, lithologic, and climatic settings: the southern California transverse ranges of the SGM, NSJM, and San Bernardino Mountains (SBM) (Binnie et al, 2007; DiBiase et al, 2010; Heimsath et al, 2012; Neely et al, 2019); the northern California Coast Ranges (NCCR) including the King Range and South Fork Eel River (Fuller et al, 2009; Moon et al, 2018); the OCR (Penserini et al, 2017); and the Guadalupe Mountains (GM) of New Mexico/Texas (Tranel & Happel, 2020). Each of these localities contains published erosion rates derived from cosmogenic radionuclides that integrate over 10 2 –10 5 year timescales.…”

Section: Compilation Of Headwater Channel Morphologies In Steep Lands...mentioning

confidence: 99%

“…For consistency, erosion rates derived from beryllium‐10 ( 10 Be) concentrations of detrital sediment were recalculated from 10 Be concentrations, sampled watershed elevations, and laboratory standards reported in publications using the CRONUS‐Earth online calculator (http://hess.ess.washington.edu, version 3; Balco et al, 2008) (see Table S1). For the GM site, which did not have detrital erosion rate estimates, we used published chlorine‐36 ( 36 Cl) derived bedrock erosion rates (Tranel & Happel, 2020). Because we focus on small (< 20 km 2 ) watersheds with broadly uniform topographic characteristics and minimal landslide influence or sediment storage, we assume that cosmogenic radionuclide concentrations reflect steady‐state erosion rates throughout each watershed.…”

Section: Compilation Of Headwater Channel Morphologies In Steep Lands...mentioning

confidence: 99%

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Sediment controls on the transition from debris flow to fluvial channels in steep mountain ranges

Neely

DiBiase

2023

Earth Surf Processes Landf

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Steep channel networks commonly show a transition from constant-gradient colluvial channels associated with debris flow activity to concave-up fluvial channels downstream. The trade-off between debris flow and fluvial erosion in steep channels remains unclear, which obscures connections among topography, tectonics, and climate in steep landscapes. Here, we analyze steep debris-flow-prone channels across the western United States and observe: (1) similar maximum channel gradients across a range of catchment erosion rates and geologic settings; and (2) lengthening colluvial channels with coarsening sediment cover. Following this compilation, we hypothesize that steep channel gradients are controlled by two competing thresholds of motion for bed-sediment cover: bed failure by mass-wasting and fluvial entrainment. We use downstream patterns in discharge, channel geometry, and sediment size to calculate discharges needed to mobilize sediment cover by both mechanisms across channels in the San Gabriel Mountains (SGM) and northern San Jacinto Mountains (NSJM) in southern California. Across steep colluvial channels in both landscapes, decadal discharges are below fluvial entrainment thresholds but above mass-wasting entrainment thresholds for D 50 (median) sediment sizes, consistent with recent debris flows captured by repeat imagery. Colluvial channel gradient is similar despite > 3Â contrasts in surface sediment grain size. In concave-up fluvial channels downstream, decadal discharges exceed fluvial entrainment thresholds, and mass-wasting is not predicted on lower gradients. In both landscapes, fluvial channels steepen downstream compared to gradients needed to mobilize sediment cover, which we interpret to reflect downstream increases in sediment flux. Coarser sediment supply in the NSJM than the SGM increases fluvial entrainment thresholds, which increases total channel relief in the NSJM by (1) lengthening colluvial channels shaped by debris flows and (2) increasing fluvial channel gradients. Our compilation and downstream analysis show how differing sensitivity of fluvial and debris flow processes to sediment grain size impacts the relative relief of colluvial and fluvial regimes in headwater channel networks.

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Section: Compilation Of Headwater Channel Morphologies In Steep Lands...mentioning

confidence: 99%

Section: Compilation Of Headwater Channel Morphologies In Steep Lands...mentioning

confidence: 99%

Sediment controls on the transition from debris flow to fluvial channels in steep mountain ranges

Neely

DiBiase

2023

Earth Surf Processes Landf

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“…Although we do not have measurements of erosion rate in Last Chance Canyon, we make the link between channel steepness and erodibility by assuming all channel reaches have a similar low-erosion rate. In other parts of the Guadalupe Mountains, west of Last Chance Canyon, erosion rates do not vary systematically with the rock type or with the slope (Tranel and Happel, 2020). We suggest that the spatial variations in erodibility, rather than spatial variations in erosion rates, control channel steepness in our study channels.…”

Section: Are Last Chance Canyon Channels Adjusted To Reflect Rock Pro...mentioning

confidence: 63%

Building a bimodal landscape: bedrock lithology and bed thickness controls on the morphology of Last Chance Canyon, New Mexico, USA

Anderson,

Gasparini,

Johnson

2023

Earth Surf. Dynam.

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Abstract. We explore how rock properties and channel morphology vary with rock type in Last Chance Canyon, Guadalupe Mountains, New Mexico, USA. The rocks here are composed of horizontally to near-horizontally interbedded carbonate and sandstone. This study focuses on first- and second-order channel sections, where the streams have a lower channel steepness index (ksn) upstream and transition to higher ksn values downstream. We hypothesize that differences in bed thickness and rock strength influence ksn values, both locally by influencing bulk bedrock strength and also nonlocally through the production of coarse sediment. We collected discontinuity intensity data (the length of bedding planes and fractures per unit area), Schmidt hammer rebound measurements, and measured the largest boulder at every 12.2 m elevation contour to test this hypothesis. Bedrock and boulder mineralogy were determined using a lab-based carbonate dissolution method. High-resolution orthomosaics and digital surface models (DSMs) were generated from drone and ground-based photogrammetry. The orthomosaics were used to map channel sections with exposed bedrock. The United States Geological Survey (USGS) 10 m digital elevation models (DEMs) were used to measure channel slope and hillslope relief. We find that discontinuity intensity is negatively correlated with Schmidt hammer rebound values in sandstone bedrock. Channel steepness tends to be higher where reaches are primarily incising through more thickly bedded carbonate bedrock and lower where more thinly bedded sandstone is exposed. Bedrock properties also influence channel morphology indirectly, through coarse sediment input from adjacent hillslopes. Thickly bedded rock layers on hillslopes erode to contribute larger colluvial sediment to adjacent channels, and these reaches have higher ksn values. Larger and more competent carbonate sediment armors both the carbonate and the more erodible sandstone and reduces steepness contrasts across rock types. We interpret that in the relatively steep, high-level ksn downstream channel sections, the slope is primarily controlled by the coarse alluvial cover. We further posit that the upstream low-level ksn reaches have a base level that is fixed by the steep downstream reaches, resulting in a stable configuration, where channel slopes have adjusted to lithologic differences and/or sediment armor.

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“…Although we do not have measurements of erosion rate in Last Chance canyon, we make the link between channel steepness and erodibility by assuming all channel reaches have a similar, low, erosion rate. In other parts of the Guadalupe Mountains, west of Last Chance canyon, erosion rates do not depend on rock type, nor on slope (Tranel, 2020). We suggest that low erodibility controls channel steepness in our study channels, and not high erosion rates.…”

mentioning

confidence: 56%

Building a Bimodal Landscape with Varying Bed Thicknesses in Last Chance Canyon, New Mexico

Anderson

Gasparini

Johnson

2022

Preprint

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Abstract. We explore how rock properties and channel morphology vary with rock type in Last Chance canyon, Guadalupe mountains, New Mexico, USA. The rocks here are composed of horizontally to near horizontally interbedded carbonate and sandstone. This study focuses on first and second order channel sections where the streams have a lower channel steepness index (ksn) upstream and transition to a higher ksn downstream. We hypothesize that differences in bed thickness and rock strength influence ksn values, both directly by influencing bulk bedrock strength but also indirectly through the production of coarse sediment. We collected discontinuity intensity data (the length of bedding planes and fractures per unit area), Schmidt hammer rebound measurements, and measured the largest boulder at every 40-foot elevation contour to test this hypothesis. Bedrock and boulder minerology was determined using a lab-based carbonate dissolution method. High resolution orthomosaics and DEMs were generated from drone photos. The orthomosaics were used to map channel sections with exposed bedrock. The high-resolution DEMs were used to measure channel slope and hillslope relief. We find that discontinuity intensity is negatively correlated with Schmidt hammer rebound values. Channel steepness is higher where reaches are primarily incising through more thickly bedded carbonate bedrock. Where there is more thinly bedded sandstone rock exposed, channel steepness tends to be lower. Furthermore, the effect that rock properties have on channel morphology is confounded by sediment input from hillslopes. Thickly bedded rock units on surrounding hillslopes contribute larger sized colluvial sediment to the channels, and these reaches have higher ksn. Larger and more competent carbonate sediment armors both the carbonate and the more erodible sandstone and dampens the negative effect sandstone bedrock has on channel steepness. We believe that in the relatively steep, high ksn downstream channel sections slope is primarily controlled by the coarse alluvial cover. We further posit that the upstream low ksn reaches have a baselevel that is essentially fixed by the steep downstream reaches, resulting in a stable configuration where channel slopes have adjusted to lithologic differences and/or sediment armor.

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Evaluating escarpment evolution and bedrock erosion rates in the western Guadalupe Mountains, West Texas and New Mexico

Cited by 3 publications

References 65 publications

Sediment controls on the transition from debris flow to fluvial channels in steep mountain ranges

Sediment controls on the transition from debris flow to fluvial channels in steep mountain ranges

Building a bimodal landscape: bedrock lithology and bed thickness controls on the morphology of Last Chance Canyon, New Mexico, USA

Building a Bimodal Landscape with Varying Bed Thicknesses in Last Chance Canyon, New Mexico

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