Geologic map of the Denver West 30' x 60' quadrangle, north-central Colorado

Kellogg, Karl S.; Shroba, Ralph R.; Bryant, Bruce; Premo, Wayne R.

doi:10.3133/sim3000

Cited by 20 publications

(16 citation statements)

References 150 publications

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“…The clasts in the profiles were weathered, although they appeared to be less weathered than those at the Table Mountain site. The coarse fraction was dominated by granites, granodiorites, gneisses, amphibolites, schists, and quartzites [ Kellogg et al , 2008], with grain sizes ranging from a few cm to about 30 cm in diameter; sizes comparable to those that dominate the Table Mountain site.…”

Section: Sampling Sites and Samplesmentioning

confidence: 99%

“…White dashed lines delineate the cross-section of the profiles shown in Figure 4; white star shows location of the Table Mountain CRN depth profile. surface is about 65 m above Ralston Creek. The Pioneer site is mapped as Verdos in age [Kellogg et al, 2008], which is inferred to correspond to an age of about 640 ka. Near our Pioneer site, closer to the mountain front, Lava Creek B ash has been reported within the gravel deposits that cap the Verdos surface [Izett and Wilcox, 1982;Van Horn, 1976;Scott, 1962].…”

Section: Pioneer Sitementioning

confidence: 99%

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Unsteady late Pleistocene incision of streams bounding the Colorado Front Range from measurements of meteoric and in situ ¹⁰Be

Dühnforth¹,

Anderson²,

Ward³

et al. 2012

J. Geophys. Res.

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Dating of gravel‐capped strath terraces in basins adjacent to western U.S. Laramide Ranges is one approach to document the history of late Cenozoic fluvial exhumation. We use in situ 10Be measurements to date the broad surfaces adjacent to the eastern edge of the Rocky Mountains in Colorado, and compare these calculated ages with results from meteoric 10Be measurements. We analyze three sites near Boulder, Colorado (Gunbarrel Hill, Table Mountain, and Pioneer) that have been mapped as the oldest terrace surfaces with suggested ages ranging from 640 ka to the Plio‐Pleistocene transition. Our in situ 10Be results reveal abandonment ages of 95 ± 129 ka at Table Mountain, 175 ± 27 ka at Pioneer, and ages of 251 ± 10 ka and 307 ± 15 ka at Gunbarrel Hill. All are far younger than previously thought. Inventories of meteoric 10Be support this interpretation, yielding ages that are comparable to Table Mountain and ∼20% lower than Pioneer in situ ages. We argue that lateral beveling by rivers dominated during protracted times of even moderate glacial climate, and that vertical incision rates of several mm/yr likely occurred during times of very low sediment supply during the few interglacials that were characterized by particularly warm climate conditions. In contrast to the traditional age chronology in the area, our ages suggest that the deep exhumation of the western edge the High Plains occurred relatively recently and at an unsteady pace.

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Section: Sampling Sites and Samplesmentioning

confidence: 99%

Section: Pioneer Sitementioning

confidence: 99%

Unsteady late Pleistocene incision of streams bounding the Colorado Front Range from measurements of meteoric and in situ ¹⁰Be

Dühnforth¹,

Anderson²,

Ward³

et al. 2012

J. Geophys. Res.

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show abstract

“…Peak snowpack accumulation occurs at the beginning of April, and peak runoff occurs in early June. The study area is underlain by metamorphosed rock (Kellogg et al, 2008) dominated by biotite schist and gneiss (Shroba et al, 2010). Upland soils are gravelly, sandy‐loams classified as Haplocryepts and Dystrocryepts formed on glacial till and colluvium (Soil Survey Staff, 2010).…”

Section: Methodsmentioning

confidence: 99%

Soil Nitrogen Leaching in Logged Beetle‐Killed Forests and Implications for Riparian Fuel Reduction

Rhoades

2019

J of Env Quality

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Recent extensive forest mortality and subsequent salvage logging may threaten the water supply from headwater catchments in western North America. Land managers confronting current insect outbreaks and projected increases in forest disturbance require information about the potential water quality consequences of these changes. This study is a hillslopescale evaluation of soil N and C leaching in lodgepole pine forests that have experienced 80% overstory tree mortality. I measured extractable inorganic and ion resin exchangeable-N forms, in situ net mineralization and nitrification, and leaching in upland and riparian forests with the following treatment combinations: (i) uncut upland with uncut riparian, (ii) harvested upland with uncut riparian buffer, and (iii) harvested upland with harvested riparian. This design permitted comparison of N cycling and leaching in 30-m-wide riparian buffers and a riparian fuel break designed to remove canopy fuels and reduce wildfire concerns in areas with extensive bark beetle infestation. Harvesting increased NO 3 -N, total dissolved N, and dissolved organic C leachate concentrations in upland landscapes but had little effect on net N transformations. Leachate N and C concentrations were 1.5 times higher in riparian buffers downslope of harvested uplands than those in riparian zones downslope of uncut uplands. Riparian forest harvest increased N leaching relative to uncut buffers, although postharvest concentrations remained well below regional water quality standards. Thus, while this study provides evidence that N leaching from dead buffers is low, it also suggests that riparian fuel reduction may complement wildfire mitigation objectives without compromising watershed protection.

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“…1996). He later co-authored (Kellogg et al. 2008) a regional compilation map that includes both Front Range and piedmont.…”

Section: University Of Colorado Family Treementioning

confidence: 99%

“…He used soils to correlate deposits locally with those throughout the Rocky Mountains (Shroba and Birkeland, 1983) and also studied soils on Rocky Flats and vicinity (Shroba and Carrara, 1996). He later co‐authored (Kellogg et al, 2008) a regional compilation map that includes both Front Range and piedmont, and his part relied a lot on soils for correlation. Before she was hired by the USGS, Reheis (1980) (Fig. )…”

Section: University Of Colorado Family Treementioning

confidence: 99%

Family Tree of USGS Soil Geomorphology Work in the Colorado Front Range and Adjacent Piedmont

Birkeland

2011

Soil Horizons

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Geologic map of the Denver West 30' x 60' quadrangle, north-central Colorado

Cited by 20 publications

References 150 publications

Unsteady late Pleistocene incision of streams bounding the Colorado Front Range from measurements of meteoric and in situ ¹⁰Be

Unsteady late Pleistocene incision of streams bounding the Colorado Front Range from measurements of meteoric and in situ ¹⁰Be

Soil Nitrogen Leaching in Logged Beetle‐Killed Forests and Implications for Riparian Fuel Reduction

Family Tree of USGS Soil Geomorphology Work in the Colorado Front Range and Adjacent Piedmont

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Geologic map of the Denver West 30' x 60' quadrangle, north-central Colorado

Cited by 20 publications

References 150 publications

Unsteady late Pleistocene incision of streams bounding the Colorado Front Range from measurements of meteoric and in situ 10Be

Unsteady late Pleistocene incision of streams bounding the Colorado Front Range from measurements of meteoric and in situ 10Be

Soil Nitrogen Leaching in Logged Beetle‐Killed Forests and Implications for Riparian Fuel Reduction

Family Tree of USGS Soil Geomorphology Work in the Colorado Front Range and Adjacent Piedmont

Contact Info

Product

Resources

About

Unsteady late Pleistocene incision of streams bounding the Colorado Front Range from measurements of meteoric and in situ ¹⁰Be

Unsteady late Pleistocene incision of streams bounding the Colorado Front Range from measurements of meteoric and in situ ¹⁰Be