Geology Commons^™

Sizes And Shapes Of 10-Ma Distal Fall Pyroclasts In The Ogallala Ggroup, Nebraska, William I. Rose, C. M. Riley, S. Dartevelle

Department of Geological and Mining Engineering and Sciences Publications

Size distributions of distal ashfall particles from correlated 10-Ma layers in Nebraska, measured using laser diffraction methods, are lognormal with mode diameters of ∼90 mm. This ashfall is ∼100% bubble-wall shards of rhyolite glass and apparently represents a distal ashfall from an eruption 1400 km away. Measured terminal velocities of these ash particles are 0.2–18 cm/s, consistent with Stokes Law settling of spherical particles with diameters of 9–50 mm. Surface area of the ash particles, measured with gas adsorption, is 20–30 times the surface area of equivalent Stokes spheres. These results highlight the effects of shape and atmospheric drag in …

Quantitative Shape Measurements Of Distal Volcanic Ash, William I. Rose, Colleen M. Riley, Gregg J. Bluth

Department of Geological and Mining Engineering and Sciences Publications

Large-scale volcanic eruptions produce fine ash (< 200 μm) which has a long atmospheric residence time (1 hour or more) and can be transported great distances from the volcanic source, thus, becoming a hazard to aircraft and public health. Ash particles have irregular shapes, so data on particle shape, size, and terminal velocities are needed to understand how the irregular-shaped particles affect transport processes and radiative transfer measurements. In this study, a methodology was developed to characterize particle shapes, sizes , and terminal velocities for three ash samples of different compositions. The shape and size of 2,500 particles from 1) distal fallout (~100 km) of the October 14, 1974 Fuego eruption (basaltic), 2) the secondary maxima (~250 km) of the August 18, 1992 Spurr eruption (andesitic), and 3) the Miocene Ash Hollow member, Nebraska (rhyolitic) were measured using image analysis techniques. Samples were sorted into 10 to 19 terminal velocity groups (0.6-59.0 cm/s) using an air elutriation device. Grain size distributions for the samples were measured using laser diffraction. Aspect ratio, feret diameter, and perimeter measurements were found to be the most useful descriptors of how particle shape affects terminal velocity. These measurement values show particle shape differs greatly from a sphere (commonly used in models and algorithms). The diameters of ash particles were 10-120% larger than ideal spheres at the same terminal velocity, indicating that irregular particle shape greatly increases drag. Gas-adsorption derived surface areas are 1 to 2 orders of magnitude higher than calculated surface areas based on measured dimensions and simple geometry, indicating that particle shapes are highly irregular. Correction factors for surface area were derived from the ash sample measurements so that surface areas calculated by assuming spherical particle shapes can be corrected to reflect more realistic values.

Retrieval Of Mass And Sizes Of Particles In Sandstorms Using Two Modis Ir Bands: A Case Study Of April 7 2001 Sandstorm In China, Yingxin Gu, William I. Rose, Gregg J. Bluth

Department of Geological and Mining Engineering and Sciences Publications

A thermal infrared remote sensing retrieval method developed by Wen and Rose [1994], which retrieves particle sizes, optical depth, and total masses of silicate particles in the volcanic cloud, was applied to an April 07, 2001 sandstorm over northern China, using MODIS. Results indicate that the area of the dust cloud observed was 1.34 million km2, the mean particle radius of the dust was 1.44 μm, and the mean optical depth at 11 μm was 0.79. The mean burden of dust was approximately 4.8 tons/km2 and the main portion of the dust storm on April 07, 2001 contained 6.5 million …

Preliminary Investigations Of Seasonal Changes In The Geochemical Evolution Of The Logdson River, Mammoth Cave, Kentucky, Chris Groves, Darlene M. Anthony, Joe Meiman

Earth, Environmental, and Atmospheric Sciences Faculty Publications

Many geochemical studies have been made of karst waters worldwide. Most data that provide the framework for our current understanding of the evolution of karst waters have come from sampling at discrete times and locations, such as springs or wells. Relatively few studies have been made of the geochemical evolution of groundwater as it moves through an open flow system. This paper addresses the seasonal changes in the geochemistry of the Logsdon River conduit as it passes through nearly 10km of the carbonate aquifer of south-central Kentucky . The most important control on the ability of groundwaters to dissolve limestone …

Could Mammoth Cave Be Reduced To A Single Equation?, Chris Groves, Joe Meiman

Earth, Environmental, and Atmospheric Sciences Faculty Publications

Since the evolution of any cave system is largely deterministic, in theory the processes responsible for this development could be described mathematically. In a practical sense, we will never have such a model to realistically describe the evolution of the Mammoth Cave System in detail. However, the search itself can provide a framework within which to understand what processes areimportant. This can guide the design of rate process studies that would eventually be coupled to provide a comprehensive understanding of the cave's evolution. Data gaps, as well, are identified during this process. The geometry of a cave system depends on …

Red Willow County Test Hole Logs, Duane A. Eversoll

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Mid-Holocene Climates Of The Americas: A Dynamical Response To Changed Seasonality, S. P. Harrison, J. E. Kutzbach, Z. Liu, P. J. Bartlein, B. Otto-Bliesner, Daniel R. Muhs, I. C. Prentice, R. S. Thompson

United States Geological Survey: Staff Publications

Abstract Simulations of the climatic response to mid- Holocene (6 ka BP) orbital forcing with two coupled ocean–atmosphere models (FOAM and CSM) show enhancement of monsoonal precipitation in parts of the American Southwest, Central America and northernmost South America during Northern Hemisphere summer. The enhanced onshore flow that brings precipitation into Central America is caused by a northward displacement of the inter-tropical convergence zone, driven by cooling of the equatorial and warming of the northern subtropical and mid-latitude ocean. Ocean feedbacks also enhance precipitation over the American Southwest, although the increase in monsoon precipitation there is largely driven by increases …

Strontium Isotope Geochemistry In The Central Part Of The Great Plains (Dakota) Aquifer, U.S.A.. Applied Geochemistry, D. C. Gosselin, F. E. Harvey, C. Frost, R. Stotler, P. A. Macfarlane

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Water Well And Spring Map Of The Hazard 30 X 60 Quadrangle, Kentucky, Bart Davidson

Map and Chart--KGS

No abstract provided.

Total Thickness Of The Amburgy Coal In Eastern Kentucky, Michael G. Shultz, Jeffery A. Esterle, Ernest E. Thacker

Map and Chart--KGS

This map showing the regional characteristics of the Amburgy coal bed was prepared as part of the U.S. Geological Survey's National Coal Assessment program, which compiles regional maps and databases that provide a comprehensive assessment of the most important coal beds in the nation. The Amburgy coal zone is composed of a number of distinct coal beds that merge in some areas to form mineable coal bodies. For the purpose of this assessment, the zone has been divided into two beds; the Lower Amburgy (A) and Upper Ambury (B). The lower bed is of greatest economic significance and is the …

Furnas County Test Hole Logs, Frank A. Smith

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Assessment Of Selected Reef Sites In Northern And South-Central Belize, Including Recovery From Bleaching And Hurricane Disturbances (Stony Corals, Algae And Fish), Paulette M. Peckol, H. Allen Curran, Emily Y. Floyd, Martha L. Robbart, Benjamin J. Greenstein, Kate L. Buckman

Geosciences: Faculty Publications

The condition of coral. algal. and fish populations in fore reefs. patch reefs, and coral reef ridges was investigated at 13 sites along the northern and south-central Belize barrier reef during May 1999, documenting effects of the 1998 warming episode and Hurricane Mitch. We found high percentages of partial, or even complete, colony mortality of major reef-builders (Acropora palmata, the Montastraea annuluris species complex and Agaricia tenuifolia) that were rarely censused as recruits. A. tenuifolia, formerly a space-dominant coral in reef ridges, had incurred nearly 100% mortality after bleaching. Nearly 45% of the M. annurluris complex …

Assessment Of Coral Reefs Off San Salvador Island, Bahamas (Stony Coral, Algae And Fish Populations), Paulette M. Peckol, H. Allen Curran, Benjamin J. Greenstein, Emily Y. Floyd, Martha L. Robbart

Geosciences: Faculty Publications

During assessments at 11 shallow reef sites on an Salvador Island, Bahamas in .iunc I998 we found low prevalence of disease, bleaching, and recent partial-colon1 mortality among stony corals (10 cm minimum dixncter). Old partial-colony mortalit) was >50% in Acropora palmata; however, recent tissue losses were low and it had recruits at several sites. Total (recent + old) partial-colony mortality of the Montastraea annularis species complex exceeded 30% on leeward patch reefs and back reefs. Groupers (serranids), snappers (lutjanids), and grunts (haemulids) were rare. Parrotfishes (scarids) were uncommon at most sites and surgeonfishes (acanthurids) were the dominant herbivores. Macroalgae, particularly …

The Role Of Lateral And Vertical Shear In Tributary Flow Toward A West Antarctic Ice Stream, Christina L. Hulbe, Weili Wang, Ian R. Joughin, Martin J. Siegert

Geology Faculty Publications and Presentations

Narrow lateral shear margins are the most distinctive visual feature of the West Antarctic ice streams. Large shear stresses within these layers support the majority of the gravitational driving stress within a fast-flowing ice stream.The present contribution looks upstream, to the tributaries that feed ice-stream onsets, and considers the effects of both horizontal and vertical shear on their flow. Numerical and direct simulations of vertical and horizontal shear are used.Vertical shear, simulated using an anisotropic flow law, is of particular interest.We conclude that by isolating overlying ice from large-amplitude variations in bed elevation -vertical shear margins - play an important …

Anisotropic Ice Flow Leading To The Onset Of Ice Stream D, West Antarctica: Numerical Modelling Based On The Observations From Byrd Station Borehole, Weili Wang, H. Jay Zwally, Christina L. Hulbe, Martin J. Siegert, Ian R. Joughin

Geology Faculty Publications and Presentations

An ice-sheet flowline model is used to simulate the flow of ice along two particle paths toward the onset to Ice Stream D,West Antarctica. One path is near the centre line of the main tributary to the ice stream, while the second passes by the Byrd Station borehole site. In this paper, we analyze the flow of the moderately fast-flowing tributaries in terms of ice-fabric anisotropy and estimate the steady-state ice-flow regions with the compatible developed crystal orientation fabrics along two particle paths. Comparison between modelled isochrones and internal layers detected from radio-echo sounding surveys in the area is used …

Water Well And Spring Map Of The Corbin 30 X 60 Minute Quadrangle, Kentucky, Bart Davidson

Map and Chart--KGS

No abstract provided.

Field Trip Guide (For The Nebraska Well Drillers Association) Northeastern Nebraska Geology, S. Olafsen-Lackey, D. Eversoll

Conservation and Survey Division: Faculty and Staff Publications

No abstract provided.

Beach Profile Evolution Under Plunging And Spilling Breakers, Ping Wang, Bruce A. Ebersole, Ernest R. Smith

Geology Faculty Publications

Beach-profile evolution, along with measurements of waves, currents, and sediment concentration, under spilling and plunging breakers of similar height were studied in the three-dimensional Large-Scale Sediment Transport Facility at the U.S. Army Engineer Research and Development Center. Unidirectional irregular waves were generated over a fine-sand beach. Beach-profile shape reached equilibrium after 1,330 and 280 min of spilling and plunging wave actions, respectively. Near the main breaker line, the profile evolved differently under plunging and spilling breakers. Across most of the midsurf zone dominated by surf bores, the equilibrium profile shapes were similar. Uniform energy dissipation per unit volume at equilibrium, …

Evaluation Of The Cerc Formula Using Large-Scale Laboratory Data, Ernest R. Smith, Ping Wang, Jun Zhang

Geology Faculty Publications

Longshore transport experiments were conducted in a large-scale physical model to evaluate predictions of the CERC formula with measured longshore sediment transport rates. It was found that the CERC formula produced reasonable estimates if the coefficient K was calibrated and applied to waves with similar breaker type. The calibrated K values are much smaller than values that are commonly used, and there appears to be a strong dependency of transport rate on breaker type. Additional comparisons were made with the formula proposed by Kamphuis (1991). The Kamphuis equation, which includes wave period, a factor that influences breaking, gave good estimates. …

Mining Geology Of The Fire Clay Coal, Stephen F. Greb

Map and Chart--KGS

The Fire Clay (Hazard No. 4) coal is one of the leading producers in the Eastern Kentucky Coal Field, with more than 20 million short tons of annual production and 230 million short tons mined between 1976 and 1992, according to Kentucky Department of Mines and Minerals data. Regional thickness and resources of the coal are calculated in Greb and others (1999c) and Thacker and others (2000a, b).

Stratigraphically, the coal occurs in the middle part of the Hyden Formation of the Breathitt Group (Fig. 1), which was previously part of the Breathitt Formation (Chesnut, 1992). The coal occurs between …

Water Well And Spring Map Of The Paducah 30 X 60 Minute Quadrangle, Kentucky, Bart Davidson

Map and Chart--KGS

No abstract provided.

Water Well And Spring Map Of The Huntington 30 X 60 Minute Quadrangle, Kentucky, Bart Davidson

Map and Chart--KGS

No abstract provided.

New Evidence For Enhanced Ocean Primary Production Triggered By Tropical Cyclone, I. Lin, W. Timothy Liu, Chun-Chieh Wu, George T. F. Wong, Chuanmin Hu, Zhiqiang Chen, Wen-Der Liang, Yih Yang, Kon-Kee Liu

OES Faculty Publications

[1] New evidence based on recent satellite data is presented to provide a rare opportunity in quantifying the long-speculated contribution of tropical cyclones to enhance ocean primary production. In July 2000, moderate cyclone Kai-Tak passed over the South China Sea (SCS). During its short 3-day stay, Kai-Tak triggered an average 30-fold increase in surface chlorophyll-a concentration. The estimated carbon fixation resulting from this event alone is 0.8 Mt, or 2-4% of SCS's annual new production. Given an average of 14 cyclones passing over the SCS annually, we suggest the long-neglected contribution of tropical cyclones to SCS's annual new production may …

Methods And Models For Estimating Advective Pore Water Exchange In Tidal Flats, Timothy J. Shaw

Faculty Publications

No abstract provided.

Hydrologic Properties And Structure Of The Mozumi Fault, Central Japan, Craig B. Forster, James P. Evans, Hidemi Tanaka, Ronald Jeffreys, Tsuyoshi Nohara

Geosciences Faculty Publications

Analyses of rocks from the Active Fault Survey Tunnel (AFST) provides insight into the structure and hydrogeology of the northeast-trending Mozumi-Sukenobu fault, an active strike-slip fault with 125 to 500 m of right-lateral slip in central Japan. Interlayered regions of sub-vertical permeability zones formed by cataclasis and slip on clay-rich foliated zones. Core samples range from 10⁻¹⁹ m² to almost 10⁻¹³ m². CFC analyses of waters from the fault zone show that water entering the tunnel is 27–36 years old, yielding a bulk fault permeability of 10⁻¹⁴ to 10⁻¹⁵ m². The …

Development Of A Regional Curve To Relate Discharge And Drainage Area To Hydraulic Geometry For The Red River Of The North Basin, Melanie H. Johnson

Theses and Dissertations

Restoration of riparian corridors and stream channels is important for many reasons, including preserving water quality, maintaining channel stability and controlling floods. Regional hydraulic geometry curves allow estimation of stable hydraulic geometry relationships that are necessary to engineer successful restoration projects. These curves can also be used to approximate discharge data for ungaged streams with lmown hydraulic geometry and drainage area. Hydraulic geometry data were collected in the field for twenty-five stream gage sites in the Red River of the North Basin. Recurrence intervals for bankfull ranged from 1.2 to 1.6 years, with an average recurrence interval of 1.4. Discharge …

Assessing The Paleoclimatic Utility Of The Indo-Pacific Coral Genus Diploastrea In A 225-Year Oxygen Isotope Record From Fiji, Stefan Bagnato

Geology Theses and Dissertations

In the Western Pacific there remains, both spatially and temporally, a sparse record of surface ocean conditions and very few long paleoclimate records able to extend our understanding of this important region. The coral genus Porites is the common coral currently used for Pacific paleoclimate studies and has proven to be very useful. The massive coral Diploastrea, due to its slow growth rate and dense structure, may preserve temporally longer geochemical proxy records than Porites colonies of the same length. Its long lifespan and fossil history give this genus great potential; however no assessment has been made of the paleoclimatic …

Late-Holocene Climate And Ecosystem History From Chesapeake Bay Sediment Cores, Usa, Debra A. Willard, Thomas M. Cronin, Stacey Verardo

United States Geological Survey: Staff Publications

Palaeoclimate records from late-Holocene sediments in Chesapeake Bay, the largest estuary in the USA, provide evidence that both decadal to centennial climate variability and European colonization had severe impacts on the watershed and estuary. Using pollen and dinoflagellate cysts as proxies for mid-Atlantic regional precipitation, estuarine salinity and dissolved oxygen (DO) during the last 2300 years, we identified four dry intervals, centred on ad 50 (P1/D1), ad 1000 (P2/D2), ad 1400 (P3) and ad 1600 (P4). Two centennial-scale events, P1/D1 and P2/D2, altered forest composition and led to increased salinity and DO levels in the estuary. Intervals P3 and P4 …

Generalized Geologic Map For Land-Use Planning: Berea 7.5-Minute Quadrangle, Kentucky, Daniel I. Carey, Martin C. Noger, Paul Howell

Map and Chart--KGS

This map is not intended to be used for selecting individual sites. Its purpose is to inform land-use planners, government officials, and the public in a general way about geologic conditions that affect the selection of sites for various purposes. Site-specific investigations should be made by a professional geologist.

Water Well And Spring Map Of The Morehead 30 X 60 Minute Quadrangle, Kentucky, Bart Davidson

Map and Chart--KGS

No abstract provided.