Open Access. Powered by Scholars. Published by Universities.®
- Keyword
- Publication Year
Articles 1 - 14 of 14
Full-Text Articles in Stratigraphy
Improving Aquifer Characterization Through Integration Of Airborne Electromagnetics (Aem) And Well Hydrographs, Jacqueline Polashek
Improving Aquifer Characterization Through Integration Of Airborne Electromagnetics (Aem) And Well Hydrographs, Jacqueline Polashek
School of Natural Resources: Dissertations, Theses, and Student Research
The objective of this study is to evaluate methods of hydrostratigraphic modeling using geophysics and well hydrographs at the eastern edge of the High Plains aquifer (HPA) in Platte and Colfax counties within Nebraska, USA. The HPA is very heterogeneous in the study area, being hosted by architecturally complex glacial sediments and having many irregular hydraulic boundaries. Further, the HPA exhibits local variations between unconfined and confined conditions. Pumping in such bounded aquifers can be unsustainable because of cost increases and lost agricultural productivity. Moreover, the large drawdowns typical of confined aquifers can contribute to well interference during heavy pumping. …
Ogallala Aquifer, Robert F. Diffendal Jr.
Ogallala Aquifer, Robert F. Diffendal Jr.
School of Natural Resources: Faculty Publications
The Ogallala Aquifer, or High Plains Aquifer, is a porous body of complex sediments and sedimentary rock formations that conducts groundwater and yields significant quantities of water to wells and springs. The principal sediments and rocks of the aquifer range in age from 33 million years old to sediments being deposited today, but the majority is less than 12 million-years old. Much of the aquifer is composed of the Ogallala Group or Formation. The dominant sediments in the Ogallala and the other hydrogeologic units in the aquifer are riverand wind-deposited sands. The aquifer underlies about 174,000 square miles of the …
Sem Analysis Of Quartz Sand Grain Surface Textures Indicates Alluvial/Colluvial Origin Of The Quaternary "Glacial" Boulder Clays At Huangshan (Yellow Mountain), East-Central China, P. E. Helland, Pei-Hua Huang, Robert F. Diffendal Jr.
Sem Analysis Of Quartz Sand Grain Surface Textures Indicates Alluvial/Colluvial Origin Of The Quaternary "Glacial" Boulder Clays At Huangshan (Yellow Mountain), East-Central China, P. E. Helland, Pei-Hua Huang, Robert F. Diffendal Jr.
School of Natural Resources: Faculty Publications
Geomorphic features and Pleistocene deposits on Huangshan have been attributed to glaciation. Recent reassessment questions this interpretation. As part of the reassessment, quartz sand grains from deposits identified as glacial boulder clays (till composed of boulders in a clay or silt matrix) were analyzed by scanning electron microscope for evidence of their sedimentary history. Surface textures found on the boulder-clay grains were compared with those on grains with known sedimentary histories including glacial, grus, colluvial, and alluvial grains. The analysis shows that the grains lack typical glacial textures. The surface textures present indicate a complex history. Non-uniformly weathered grain surfaces …
Geologic History Of Ash Hollow State Historical Park, Nebraska, Robert F. Diffendal Jr., Roger K. Pabian, J. R. Thomasson
Geologic History Of Ash Hollow State Historical Park, Nebraska, Robert F. Diffendal Jr., Roger K. Pabian, J. R. Thomasson
Conservation and Survey Division
Contents:
Introduction
Acknowledgments
Cautions
General Stratigraphy
Oligocene Series-White River Group-Brule Formation-Whitney Member
Miocene Series-Ogallala Group-Ash Hollow Formation
Pliocene Series-Broadwater Formation
Quaternary deposits
Older colluvium and loess
Younger colluvium and alluvium
General Paleontology
Evidence of past life: fossils and subfossils
Collecting fossils
Vertebrate fossils
Fossils from the Whitney Member of the Brule Formation
Plants
Invertebrates
Vertebrates
Fossils from the Ash Hollow Formation
Plants
Invertebrates
Vertebrates
Fossils from the Broadwater Formation
Plants
Vertebrates
Quaternary fossils
Plants
Invertebrates
Vertebrates
Additional studies of Nebraska fossils
Geologic History
Prehistory and History
References
Appendices I-IV
Scanning Electron Microscopic Study Of Quartz Sand Surface Features, Ash Hollow Formation, Ogallala Group, Western Nebraska, Patricia E. Helland, Robert F. Diffendal Jr.
Scanning Electron Microscopic Study Of Quartz Sand Surface Features, Ash Hollow Formation, Ogallala Group, Western Nebraska, Patricia E. Helland, Robert F. Diffendal Jr.
School of Natural Resources: Faculty Publications
In field studies of the late Tertiary Ash Hollow Formation of the Ogallala Group in western Nebraska the alluvial deposits are composed of large volumes of sand and gravel up to large cobbles. Because the current understanding of the climate of the region at the time of deposition does not provide for a source for deposits of this character, a scanning electron microscopic study of the surface features on the quartz sand grains from these sediments was undertaken. Nine samples, collected from locations in Banner, Morrill and Keith Counties, were examined to see if they had one or more of …
Late Paleozoic Cyclic Sedimentation In Southeastern Nebraska: A Field Guide, Roger K. Pabian, Robert F. Diffendal Jr.
Late Paleozoic Cyclic Sedimentation In Southeastern Nebraska: A Field Guide, Roger K. Pabian, Robert F. Diffendal Jr.
School of Natural Resources: Faculty Publications
People studying and collecting sedimentary rocks, minerals, and fossils in eastern Nebraska often find that locating rock exposures can be difficult. Most of the rolling hills in the eastern sixth of the state are underlain by thick, interlayered, glacial deposits, loess (windblown silt), and alluvium (stream-deposited sediments) of very young geologic age. These sediments cover the bedrock in most of that area. Natural exposures and human excavations of bedrock are mostly confined to the sides and floors of stream valleys. However, in the southeasternmost counties of the state, the younger sediment cover is commonly thin or absent. Pawnee and Richardson …
Middle Miocene To Recent Stratigraphy And Paleogeography Of Western Nebraska, James B. Swinehart, Vernon L. Souders, H. M. Degraw, Robert F. Diffendal Jr.
Middle Miocene To Recent Stratigraphy And Paleogeography Of Western Nebraska, James B. Swinehart, Vernon L. Souders, H. M. Degraw, Robert F. Diffendal Jr.
School of Natural Resources: Faculty Publications
Two generally distinctive suites of sediments occur in western Nebraska, one dominantly volcaniclastic in origin deposited from the Oligocene through Early Miocene, and the other mainly epiclastic in origin deposited from the Middle Miocene through the Holocene. We have combined the epiclastic deposits usually placed in the Hemingford and Ogallala groups into an expanded Ogallala Group and have abandoned the member subdivisions of the Broadwater Formation.
New Evidence Supporting The Blancan Age Of The Sand And Gravel Sequence Capping The Ash Hollow Formation, Garden, Keith, And Lincoln Counties, Nebraska, Robert F. Diffendal Jr., James W. Goeke, Michael R. Voorhies
New Evidence Supporting The Blancan Age Of The Sand And Gravel Sequence Capping The Ash Hollow Formation, Garden, Keith, And Lincoln Counties, Nebraska, Robert F. Diffendal Jr., James W. Goeke, Michael R. Voorhies
School of Natural Resources: Faculty Publications
Sandwiched between the overlying eolian Quaternary loesses and sands and the underlying beds of the Ash Hollow Formation, Ogallala Group, buried beneath the sliver of Cheyenne Tableland in Keith County and adjacent areas of western Nebraska, is a mass of fluvially deposited sand, gravelly sand, and sandy gravel of previously uncertain age. Some authors assigned these sediments to the Ogallala Group, while others have called them either the Broadwater Formation (Blancan), or a combination of the two rock units.
The Inapplicability Of The Concept Of The "Sidney Gravel" To The Ogallala Group (Late Tertiary) In Part Of Southern Banner County, Nebraska, Robert F. Diffendal Jr.
The Inapplicability Of The Concept Of The "Sidney Gravel" To The Ogallala Group (Late Tertiary) In Part Of Southern Banner County, Nebraska, Robert F. Diffendal Jr.
School of Natural Resources: Faculty Publications
A series of geologic maps of counties in western Nebraska was prepared for the Nebraska Geological Survey during the mid-1 930s. These maps showed the distribution of rock units of Tertiary age including a formation designated as the “Sidney.” The Sidney Gravel was described as a widespread sheetlike complex of channel deposits, but with small areas where it is not developed. In southern Banner County, Nebraska, there are several channels filled with sand and gravel that were mapped as Sidney in this series. Recently one of these channel fills has been observed to cut across the other. The fills are …
Further Comments On The Nature And Developmental History Of Quaternary Pumpkin Creek, Banner, And Morrill Counties, Nebraska, Robert F. Diffendal Jr.
Further Comments On The Nature And Developmental History Of Quaternary Pumpkin Creek, Banner, And Morrill Counties, Nebraska, Robert F. Diffendal Jr.
School of Natural Resources: Faculty Publications
The occurrence of Quaternary anorthosite-rich sand and gravel deposits in south-central Morrill County, Nebraska, supports the idea that Pumpkin Creek formerly flowed farther east than it does today. This eastern extension of the creek was abandoned when another headward cutting tributary of the North Platte River cut through the divide between Pumpkin Creek and the North Platte just east of Jail and Courthouse rocks and captured Pumpkin Creek.
Unusual clast types found in Quaternary deposits along Pumpkin Creek in Banner County may be used to determine some characteristics of the streams that carried them. For example, armored mud balls and …
Geometries And General Features Of Some Cenozoic Valleys And Valley Fills, Western Nebraska, Robert F. Diffendal Jr.
Geometries And General Features Of Some Cenozoic Valleys And Valley Fills, Western Nebraska, Robert F. Diffendal Jr.
School of Natural Resources: Faculty Publications
Portions of Tertiary and Quaternary valleys and valley fills have been exhumed by recent stream erosion at many sites in western Nebraska. Paleovalleys vary from narrow, steep-sided, high gradient tributary gullies less than 0.1 km wide to broad, flat-floored valleys produced by lateral erosion. Segments of valley floors may be nearly smooth in the case of a Quaternary example, or may be very irregular with potholes and other deep scour features. Paleovalley sides, when exposed, are often steeply sloping, and approaching or possibly going beyond the vertical where the valleys have been eroded into the Brule Formation. Paleovalleys range in …
A Gering Formation (Miocene) Pumice Conglomerate And Associated Beds From Broadwater, Nebraska, Robert F. Diffendal Jr.
A Gering Formation (Miocene) Pumice Conglomerate And Associated Beds From Broadwater, Nebraska, Robert F. Diffendal Jr.
School of Natural Resources: Faculty Publications
The Mitchell Pass Member of the Gering Formation was defined by Vondra, Schultz, and Stout in 1969 on the basis of exposures in the Wildcat Ridge area of western Nebraska. The basal part of the member in many areas of Wildcat Ridge is a pumice-pebble conglomerate bed. A newly discovered pumice-pebble conglomerate locality occurs north of Broadwater, Nebraska, some twenty miles east of the easternmost previously reported exposure of the pumice conglomerate at Redington Gap on Wildcat Ridge. Pumice samples from Redington Gap and Broadwater have the same index of refraction and similar inclusions. Beds above the conglomerate and below …
Microfossils From The Big Springs Limestone (Pennsylvanian) In Nebraska, Robert F. Diffendal Jr.
Microfossils From The Big Springs Limestone (Pennsylvanian) In Nebraska, Robert F. Diffendal Jr.
School of Natural Resources: Faculty Publications
Sand-sized residues from partial acetic acid digestion of three samples of the Big Springs Limestone Member of the Lecompton Limestone (Pennsylvanian) from two localities in Cass County, Nebraska, have yielded sixteen genera of microfossils from five major groups of organisms and numerous other whole and partial fossils from seven other groups not identified to the genus level. These fossils include: Protozoa (fusulinids*); Porifera (one spicule type); Bryozoa (two undetermined genera); Brachiopoda (fragments); Gastropoda (two undetermined forms); Ostracoda (Bairdia*, Hollinella*, Moorites*, and one undetermined genus); Crinoidea (whole and partial ossicles*); Echinoidea (whole and partial spines and spine bases*); Holothuroidea (Achistrum …
Microfossils From The Upper Severy Shale (Pennsylvanian) Near Dubois, Nebraska, Robert F. Diffendal Jr.
Microfossils From The Upper Severy Shale (Pennsylvanian) Near Dubois, Nebraska, Robert F. Diffendal Jr.
School of Natural Resources: Faculty Publications
Organic rich limestone nodules within the Severy Shale Formation collected directly above the Nodaway Coal Member near DuBois, Nebraska, have yielded a rich microflora and microfauna. The microflora includes Triletes megaspores, seeds, cuticle, and pieces of wood with well preserved structures. The microfaunal skeletal material is either partially or completely replaced by pyrite, marcasite, or, in rare cases, by sphalerite. The following major invertebrate groups and genera within these groups have been identified to date: Bryozoa (one undetermined genus); Brachiopoda (Juresania) ; Gastropoda (four undetermined genera); Ammonoidea (one undetermined genus); Ostracoda (Amphissites, Coryellites, Hollinella, Macrocypris); Echinoidea (five spine types); and …