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ogallala group

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Journal Article
Journal: Geology
Published: 01 January 2002
Geology (2002) 30 (1): 63–66.
... postdepositional changes in slope can be determined. Miocene to earliest Pliocene gravels of the Ogallala Group (17.5–5 Ma) cap the tablelands, which currently tilt down to the east at slopes as great as 10 −2 . However, paleohydraulic analysis of the Ogallala gravels indicates depositional slopes of 10 −3 to 10...
FIGURES | View All (4)
Journal Article
Published: 01 March 1998
Journal of Paleontology (1998) 72 (2): 388–397.
...Mark L. Gabel; Douglas C. Backlund; Jacob Haffner Abstract The results of the first comprehensive paleobotanical survey of the northern portion of the late Miocene Ogallala Group are discussed. Several species of fossilized fruiting structures from vascular plants (Berriochloa, Celtis, Cryptantha...
Journal Article
Published: 01 October 1992
Rocky Mountain Geology (1992) 29 (2): 97–109.
Journal Article
Published: 01 December 1988
Rocky Mountain Geology (1988) 26 (2): 57–97.
Journal Article
Journal: Geology
Published: 01 August 1987
Geology (1987) 15 (8): 705–708.
...Dale A. Winkler Abstract The upper Couch Formation is part of the lower of two formations composing the Ogallala Group in Blanco and Yellowhouse canyons in northwestern Texas. An eolian origin for the upper Couch Formation is indicated by its mean grain size, pedogenic carbonate nodules, massive...
Journal Article
Published: 01 December 1983
Rocky Mountain Geology (1983) 22 (2): 109–115.
Journal Article
Journal: GSA Bulletin
Published: 01 October 1982
GSA Bulletin (1982) 93 (10): 964–976.
...R. F. DIFFENDAL, Jr. Abstract A part of a filled Ogallala Group (upper Tertiary) paleovalley system exhumed by recent stream erosion in southwestern Morrill County, Nebraska, and adjacent areas contains steep gradient gullies filled with locally derived sediments. Younger channels filled...
Journal Article
Published: 01 January 1971
Journal of Paleontology (1971) 45 (1): 119–121.
Image
Summary of tilted paleosurfaces on the Great Plains. (A) <b>Ogallala</b> <b>Group</b> sed...
in > Geosphere
Published: 01 June 2013
Figure 16. Summary of tilted paleosurfaces on the Great Plains. (A) Ogallala Group sediments have been tilted at an angular rate of ∼9 millidegrees/Ma since 17.5 Ma in western Nebraska and southern Wyoming. Plot is modified from McMillan et al. (2002) . (B) Differential tilting of Ogallala Group
Journal Article
Published: 01 March 1979
Journal of Sedimentary Research (1979) 49 (1): 45–53.
... and Ogallala Groups of the High Plains sequence (Oligocene to Pliocene) have 87 Sr/ 86 Sr ratios ranging from 0.7065 for plagioclase arenite to 0.7491 for arkosic arenite. Rhyolitic vitric ash samples have intermediate 87 Sr/ 86 Sr ratios of 0.7093 and 0.7133. In contrast to the detrital fractions...
Series: DNAG, Centennial Field Guides
Published: 01 January 1988
DOI: 10.1130/0-8137-5404-6.299
EISBN: 9780813754109
...). Within a distance of 5.5 mi (8.9 km), the highway descends from the High Plains through the Bridwell and Couch Formations (Ogallala Group) to Triassic red beds before climbing back onto the High Plains surface. The route passes near the Bridwell and Couch type sections and is flanked by several excellent...
Series: SEPM Special Publication, SEPM Special Publication
Published: 01 January 1987
DOI: 10.2110/pec.87.39.0149
EISBN: 9781565760967
... Abstract Stratification and estimated paleoflow conditions for valley-fill deposits suggest that Ogallala Group streams in western Nebraska were similar to modern streams of south-central Alberta. Ogallala stratification includes medium-scale (0.5 to 2.0 m thick) trough crossbedded sand...
Journal Article
Journal: Geology
Published: 01 October 2012
Geology (2012) 40 (10): 871–874.
... collected from Late Miocene Ogallala Group and Pliocene Broadwater Formation of the Nebraskan Great Plains demonstrates a twofold increase in the median grain size (from 20 mm to >40 mm) exported from the Rocky Mountains across the Miocene-Pliocene boundary. Paleoslope reconstructions derived from...
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Journal Article
Journal: GSA Bulletin
Published: 01 September 2003
GSA Bulletin (2003) 115 (9): 1122–1132.
...) the Shinarump Conglomerate of Late Triassic age exposed in northern Arizona and adjacent parts of Utah, Nevada, and New Mexico; (2) Lower Cretaceous gravel deposits that overlie the Morrison Formation throughout the Rocky Mountain region; and (3) the gravel-rich parts of the Miocene-Pliocene age Ogallala Group...
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Journal Article
Published: 01 July 1964
Journal of Paleontology (1964) 38 (4): 773–775.
... Formation in Wyoming, the Truckee Diatomite in Nevada, and the Ogallala Group in South Dakota. Phytoliths were found in all but the Green River and Truckee, being especially common near the base of the Flagstaff and in several beds of the Ogallala. This survey suggests that phytoliths can be useful...
Journal Article
Journal: GSA Bulletin
Published: 01 November 2008
GSA Bulletin (2008) 120 (11-12): 1362–1377.
... detrital zircons suggests additional minor contributions of silt from the Oligocene-Miocene Arikaree Group and Miocene Ogallala Group. Isotopic data from detrital K-feldspar and zircon grains from Peoria Loess deposits in eastern Nebraska and western Iowa suggest that the immediate source of this loess...
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Journal Article
Journal: PALAIOS
Published: 01 November 2013
PALAIOS (2013) 28 (11): 793–824.
...R. M. JOECKEL; S. T. TUCKER Abstract Dozens of well-preserved fossil burrow systems in upper Miocene sedimentary rocks of the Ogallala Group at a site in east-central Nebraska record rodent behavior and the subsurface ecology of grasslands just as the modern Great Plains was developing...
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Series: GSA Memoirs
Published: 01 January 1969
DOI: 10.1130/MEM113-p1
... The early Pleistocene (Blancan) Rita Blanca lake deposits in the north-western part of the Panhandle of Texas occupy a deflation basin cut through the caprock of the Pliocene Ogallala Group. During its maximum development, Rita Blanca lake had an elliptical shape with a north-south length...
Journal Article
Journal: AAPG Bulletin
Published: 01 October 1946
AAPG Bulletin (1946) 30 (10): 1742–1746.
... 12 the presence of such reefs with similar lithologic characteristics in the capping limestone of the Ogallala in western Kansas, and also in western Nebraska, where this unit has been placed at the top of the Kimball formation of the Ogallala group. 13 The algae and associated lithologic...
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