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Strategies For Reducing Stored Feed Requirements, Don Ball Oct 2004

Strategies For Reducing Stored Feed Requirements, Don Ball

Kentucky Grazing Conference

A basic, desirable goal for virtually any livestock producer is to minimize stored feed requirements. It is less expensive to have livestock harvest forage for themselves by grazing than to harvest it for them; therefore, the greater the extent to which pasture can be used to provide nutrition, the more profitable a livestock operation will generally be. Thus, it is worthwhile to consider all options that might be available for reducing stored feed needs.


Stocking Decisions: They Make Or Break You, Glen E. Aiken Oct 2004

Stocking Decisions: They Make Or Break You, Glen E. Aiken

Kentucky Grazing Conference

Decisions on species and variety of forage to plant and manage are economically critical because it establishes the potential to meet a particular production goal. However, the stocking rate used to graze these forages is more critical because it ultimately determines if a targeted level of production is reached. Most cattlemen aim for a stocking rate that provides maximum economic return, but it should be emphasized that an economically optimum stocking rate is one that potentially provides sustained economic return. It is obvious that dollar return is not maximized if excessive heavy grazing results in costly pasture renovation, ranging from …


Grazing: Getting From Where You Are To Where You Want To Be, Gary Bates Oct 2004

Grazing: Getting From Where You Are To Where You Want To Be, Gary Bates

Kentucky Grazing Conference

When trying to design a forage and grazing program, producers often try to consider so many factors that it becomes mind-boggling. If basic plant physiology, how and when a forage plant grows is considered, improving a forage program will usually become easier, especially in developing a controlled grazing system. The purpose of a controlled grazing system should be to improve the utilization of the high quality forage produced on the farm. In order to improve this utilization, it is helpful to understand plant growth and quality, and the factors that affect them.


Will Improved Grazing Pay For Extra Fencing And Water Cost?, Ken Johnson Oct 2004

Will Improved Grazing Pay For Extra Fencing And Water Cost?, Ken Johnson

Kentucky Grazing Conference

Expectation is founded on faith, and in faith lays opportunities. I suppose as we look at most farming operations most changes occur from force not by choice. What I propose today and hope to convince most of you; is that here is an opportunity to make more profit, if you’re willing to change and have faith that it will work. Most of us have heard of, if not practiced rotation grazing for a long time. The question many ask, is it worthwhile. Does better grazing management make me any more money? I hope to at least provide some insight as …


Present And Future Tall Fescue Varieties, Timothy D. Phillips Oct 2004

Present And Future Tall Fescue Varieties, Timothy D. Phillips

Kentucky Grazing Conference

Tall fescue has played a key role in forage production over the past century in the USA. It has other uses besides forage applications, such as turf, mine reclamation, and highway rights-of-way, but in this presentation we will focus on forage varieties. Several hundred turf-type tall fescue varieties have been developed over the past 30 years, mainly by private seed companies using material from Reed Funk at Rutgers University in New Jersey. Forage varieties aren’t as numerous. I will discuss some of the older and current forage tall fescue varieties, and finish by discussing the newest varieties, and those that …


Fertilizing Pastures For Profit, Byron Sleugh Oct 2004

Fertilizing Pastures For Profit, Byron Sleugh

Kentucky Grazing Conference

It has been known for centuries that providing certain nutrients to plants is critical for high productivity. The nutrient source and manner in which it is applied may vary, but the desired outcome is the same: high crop yield and quality. Fertilization is the most practical means that producers have to ensure that crops receive the nutrients they need. While increasing fertilizer application and managing pH by liming can lead to increase forage production, your investment should be measured against the potential return. Also, over application of nutrients can potentially cause environmental problems.


Role Of Legumes In Pasture Systems, Garry D. Lacefield Oct 2004

Role Of Legumes In Pasture Systems, Garry D. Lacefield

Kentucky Grazing Conference

Successful livestock programs are dependent on forage programs which supply large quantities of adequate quality, homegrown feed. A major percentage of the feed units for beef (83%) and dairy (61%) cattle come from forages. In addition, forages supply an estimated 91%, 72%, 15% and 99% of the nutrients consumed by sheep and goats, horses, swine and ruminant wildlife, respectively. These values can be put in perspective when we consider that 63% of Kentucky's Agricultural Cash Receipts are from livestock and livestock products. Cash hay accounts for approximately 28% of the total crop value. Hay ranks second only to tobacco in …


Foreword And Kfgc Award Winners [2004], Garry D. Lacefield, Christi L. Forsythe Oct 2004

Foreword And Kfgc Award Winners [2004], Garry D. Lacefield, Christi L. Forsythe

Kentucky Grazing Conference

No abstract provided.


Assessment Of Engineering Mechanics Instructional Multimedia In A Variety Of Instructional Settings, Richard H. Hall, Nancy Hubing, Timothy A. Philpot, Ralph E. Flori, Vikas Yellamraju Oct 2004

Assessment Of Engineering Mechanics Instructional Multimedia In A Variety Of Instructional Settings, Richard H. Hall, Nancy Hubing, Timothy A. Philpot, Ralph E. Flori, Vikas Yellamraju

Business and Information Technology Faculty Research & Creative Works

Students from Ten Schools, Representing Seven Countries, Used Interactive Multimedia as a Part of their Engineering Statics Classes. the Software Consisted of Four Modules, Which Focused On: Mohr's Circle; Centroid and Moment of Inertia; Stress Transformation; and Structural Analysis. the Students Completed On-Line Surveys About their Experience with the Software. Analysis of the Results Indicated that Students Rated their Knowledge of the Subject Matter Covered in the Software as Increasing Significantly as a Consequence of using the Software. However, This Increase Was Substantially More Pronounced for Students in U.S. Schools. Students Rated the Software as Significantly More Effective Than their …


Long-Term Mechanical Behavior Of Yucca Mountain Tuffs, And Its Variability, Jaak J.K. Daemen, George Danko, Jaime Gonzalez, Amy J. Smiecinski, Raymond E. Keeler Oct 2004

Long-Term Mechanical Behavior Of Yucca Mountain Tuffs, And Its Variability, Jaak J.K. Daemen, George Danko, Jaime Gonzalez, Amy J. Smiecinski, Raymond E. Keeler

Publications (YM)

We propose to continue the investigation of the long term strength of Yucca Mountain tuffs, with particular emphasis on tuffs from and near the emplacement horizon. We propose to also continue and expand the investigation of the spatial variability of rock strength and stiffness. An intrinsic component of this planned rock testing is the testing of rock joints. Although the emphasis is on tests aimed at determining long term strength, as part of the testing measurements of stiffness also are collected, and will be collected, reported, and analyzed.


Modeling Long-Term Volcanic Hazards Through Bayesian Inference: An Example From The Tohoku Volcanic Arc, Japan, Andrew J. Martin, Koji Umeda, Charles B. Connor, Jennifer N. Weller, Dapeng Zhao, Masaki Takahashi Oct 2004

Modeling Long-Term Volcanic Hazards Through Bayesian Inference: An Example From The Tohoku Volcanic Arc, Japan, Andrew J. Martin, Koji Umeda, Charles B. Connor, Jennifer N. Weller, Dapeng Zhao, Masaki Takahashi

Geology Faculty Publications

The need to quantitatively estimate future locations of volcanoes in the long-term is of increasing importance, partly as a result of the requirement of constructing certain types of installations in regions of low geologic risk. The complex geological factors and natural processes controlling the locations of volcanoes make it problematic to estimate future patterns deterministically. Instead, the probabilistic approach can be developed with quite high levels of confidence; however, for regions with few or no volcanoes, there is a need to include additional geological and geophysical data that may indicate the likelihood of future volcanism. We achieve this using Bayesian …


Low Marine Sulphate And Protracted Oxygenation Of The Proterozoic Biosphere, Linda C. Kah, Timothy W. Lyons, Tracy D. Frank Oct 2004

Low Marine Sulphate And Protracted Oxygenation Of The Proterozoic Biosphere, Linda C. Kah, Timothy W. Lyons, Tracy D. Frank

Department of Earth and Atmospheric Sciences: Faculty Publications

Progressive oxygenation of the Earth’s early biosphere is thought to have resulted in increased sulphide oxidation during continental weathering, leading to a corresponding increase in marine sulphate concentration. Accurate reconstruction of marine sulphate reservoir size is therefore important for interpreting the oxygenation history of early Earth environments. Few data, however, specifically constrain how sulphate concentrations may have changed during the Proterozoic era (2.5–0.54 Gyr ago). Prior to 2.2 Gyr ago, when oxygen began to accumulate in the Earth’s atmosphere, sulphate concentrations are inferred to have been <200 >μM, on the basis of limited isotopic variability preserved in sedimentary sulphides4 and experimental …


Surface Temperature And Spectral Measurements At Santiaguito Lava Dome, Guatemala, Steve T. M. Sahetapy-Engel, Luke P. Flynn, Andrew J. L. Harris, Gregg J. Bluth, William I. Rose, Otoniel Matias Oct 2004

Surface Temperature And Spectral Measurements At Santiaguito Lava Dome, Guatemala, Steve T. M. Sahetapy-Engel, Luke P. Flynn, Andrew J. L. Harris, Gregg J. Bluth, William I. Rose, Otoniel Matias

Department of Geological and Mining Engineering and Sciences Publications

An infrared thermometer, spectroradiometer and digital video camera were used to observe and document short-term evolution of surface brightness temperature and morphology at Santiaguito lava dome, Guatemala. The thermometer dataset shows 40–70 minute-long cooling cycles, each defined by a cooling curve that is both initiated and terminated by rapid increases in temperature due to regular ash venting. The average cooling rate calculated for each cycle range from 0.9 to 1.6°C/min. We applied a two-component thermal mixture model to the spectroradiometer (0.4–2.5 μm) dataset. The results suggest that the observed surface morphology changed from a cool (120–250°C) crust-dominated surface with high …


High Dispersal In A Frog Species Suggests That It Is Vulnerable To Habitat Fragmentation, W. Chris Funk, Allison E. Greene, Paul Stephen Corn, Fred W. Allendorf Oct 2004

High Dispersal In A Frog Species Suggests That It Is Vulnerable To Habitat Fragmentation, W. Chris Funk, Allison E. Greene, Paul Stephen Corn, Fred W. Allendorf

United States Geological Survey: Staff Publications

Global losses of amphibian populations are a major conservation concern and their causes have generated substantial debate. Habitat fragmentation is considered one important cause of amphibian decline. However, if fragmentation is to be invoked as a mechanism of amphibian decline, it must first be established that dispersal is prevalent among contiguous amphibian populations using formal movement estimators. In contrast, if dispersal is naturally low in amphibians, fragmentation can be disregarded as a cause of amphibian declines and conservation efforts can be focused elsewhere. We examined dispersal rates in Columbia spotted frogs (Rana luteiventris) using capture–recapture analysis of over …


Mechanisms Of Lead, Copper, And Zinc Retention By Phosphate Rock, Xinde Cao, Lena Q. Ma, Dean R. Rhue, Chip S. Appel Oct 2004

Mechanisms Of Lead, Copper, And Zinc Retention By Phosphate Rock, Xinde Cao, Lena Q. Ma, Dean R. Rhue, Chip S. Appel

Earth and Soil Sciences

The solid–liquid interface reaction between phosphate rock (PR) and metals (Pb, Cu, and Zn) was studied. Phosphate rock has the highest affinity for Pb, followed by Cu and Zn, with sorption capacities of 138, 114, and 83.2 mmol/kg PR, respectively. In the Pb–Cu–Zn ternary system, competitive metal sorption occurred with sorption capacity reduction of 15.2%, 48.3%, and 75.6% for Pb, Cu, and Zn, respectively compared to the mono-metal systems. A fractional factorial design showed the interfering effect in the order of Pb > Cu > Zn. Desorption of Cu and Zn was sensitive to pH change, increasing with pH decline, whereas Pb …


Evaluating Uranium Depth Versus Socio-Economic Statistics For Residential Radon Vulnerability In Warren County, Kentucky, Anthony Iovanna Oct 2004

Evaluating Uranium Depth Versus Socio-Economic Statistics For Residential Radon Vulnerability In Warren County, Kentucky, Anthony Iovanna

Masters Theses & Specialist Projects

Residences in Warren County, Kentucky, are characterized by high levels of residential radon, which is one of the radioactive daughter products of uranium. According to the United States Environmental Protection Agency (US EPA), radon exposure causes approximately 22,000 lung cancer deaths in the United States per year. The City of Bowling Green, in Warren County, is underlain by karst, an easily soluble limestone subsurface, which allows radon gas to travel easily through cracks and fissures. Carbonate rocks under Bowling Green are underlain by the Devonian Chattanooga Shale, a low-grade uranium ore and a potential source of radon gas. A digital …


Wetland Basins For Saline Drainage Water Disposal Bodallin And Elachbutting Catchments, Eastern Wheatbelt, Western Australia, P De Broekert, N Coles Oct 2004

Wetland Basins For Saline Drainage Water Disposal Bodallin And Elachbutting Catchments, Eastern Wheatbelt, Western Australia, P De Broekert, N Coles

Resource management technical reports

This report provides an assessment of two large deep drainage schemes within the lower reaches of the Bodallin and Elachbutting Catchments nearby Merredin in Western Australia, wherein groups of isolated wetland basins have been utilised for evaporative saline drainage water disposal. In both cases, the storage capacity of the basins has been exceeded, leading to flooding and death of the surrounding native vegetation.


Geogram 2004, David J. Keeling Editor, Wku Department Of Geography And Geology Oct 2004

Geogram 2004, David J. Keeling Editor, Wku Department Of Geography And Geology

Earth, Environmental, and Atmospheric Sciences Publications

No abstract provided.


Earth News, V28, Fall 2004, Department Of Earth Science, University Of Northern Iowa. Oct 2004

Earth News, V28, Fall 2004, Department Of Earth Science, University Of Northern Iowa.

Earth News

Inside this issue:

--- Earth Science Staff Activities
--- Earth Science Majors
--- Student Internships
--- From Ocean to Ice: GSI 2004 Spring Field Trip Highlights
--- National Earth Science Week Quarry Open House
--- Sigma Gamma Epsilon - Gamma Sigma Chapter
--- Student Research Presentation
--- 2004-2005 Scholarship and Award Recipients
--- 2004 Earth Science Graduates
--- Earth Science Seminar Series
--- Gifts to the Department of Earth Science
--- Earth Science Alumni News


Hydrologic Variations Within Created And Natural Wetlands In Southeastern Virginia, Aaron Dyer Despres Oct 2004

Hydrologic Variations Within Created And Natural Wetlands In Southeastern Virginia, Aaron Dyer Despres

OES Theses and Dissertations

The hydrology of wetlands, particularly how wetland soils collect, store, and redistribute water strongly affects how wetland systems function. In created wetlands, construction processes and materials influence the hydrology and consequently, the potential for successful reestablishment of target vegetation communities. During .2002- 2004, the Virginia Department of Transportation constructed large mitigation wetlands on two different Quaternary aged surfaces with very similar hydrogeomorphic conditions. The Sandy Bottom Nature Park site (SBNP) located in Hampton, VA and rests on the sandy loam Tabb Formation while the Charles City Wetland site (CCW) lies on the older and clay-rich Shirley Formation. This study documents …


Significant Crustal Thinning Beneath The Baikal Rift Zone: New Constraints From Receiver Function Analysis, Stephen S. Gao, Kelly H. Liu, Chizheng Chen Oct 2004

Significant Crustal Thinning Beneath The Baikal Rift Zone: New Constraints From Receiver Function Analysis, Stephen S. Gao, Kelly H. Liu, Chizheng Chen

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Thinning of the crust of more than 10 km is a major feature of typical continental rifts such as the East African (EAR) and Rio Grande (RGR) rifts. However, numerous previous studies across the Baikal rift zone (BRZ), which has similar surface expressions and tectonic history, and more active seismicity relative to EAR and RGR, have resulted in contradicting amount of thinning, ranging from almost none to more than 10 km. We measure crustal thickness by stacking teleseismic receiver functions beneath 51 sites on the southern and central parts of the BRZ and adjacent Siberian Platform and Sayan-Baikal-Mongolian Foldbelt. Our …


Influence Of Lithophysae Geometry And Distribution On Mechanical Properties Of Topopah Spring Tuff, Mohammad Shahidul Islam, Justin Fenton, Moses Karakouzian, Jaime Gonzalez, Amy J. Smiecinski, Raymond E. Keeler Sep 2004

Influence Of Lithophysae Geometry And Distribution On Mechanical Properties Of Topopah Spring Tuff, Mohammad Shahidul Islam, Justin Fenton, Moses Karakouzian, Jaime Gonzalez, Amy J. Smiecinski, Raymond E. Keeler

Publications (YM)

The current Site Recommendation study for the proposed high level nuclear waste repository at Yucca Mountain locates the repository emplacement drifts approximately 81% within the lower lithophysal unit of the Topopah Springs Formation (Tptpll), 4% within the upper lithophysal unit of the Topopah Springs Formation (Tptpul), and roughly 15% within the middle, non-lithophysal unit (Tptpmn) of the same formation. A major geomechanical issue facing the Yucca Mountain Project is to understand the thermomechanical behavior of lithophysal tuff, which comprises roughly 85% of the repository host rock.


Technical Assessment Of Natural Resource Management Threats And Options In The Northern Agricultural Region Of Western Australia, Lorinda Hunt, G Patterson, Northern Agricultural Catchments Council (Wa) Sep 2004

Technical Assessment Of Natural Resource Management Threats And Options In The Northern Agricultural Region Of Western Australia, Lorinda Hunt, G Patterson, Northern Agricultural Catchments Council (Wa)

Resource management technical reports

Analysis of the risk of soil, land and water degradation within the Northern Agricultural Region of Western Australia. Natural resource issues discussed include: acid groundwater, acid sulfate soils, climate change, dryland salinity, flooding, herbicide resistance, non-wetting (water repellence), nutrient loss and eutrophication, remnant vegetation decline, soil acidity, soil fertility decline, soil structure decline, subsurface compaction, waterlogging, wind erosion and soil contamination.


Correction To ‘‘A Concept Of Maximum Stream Depletion Rate For Leaky Aquifers In Alluvial Valleys" By Vitaly A. Zlotnik, Vitaly A. Zlotnik Sep 2004

Correction To ‘‘A Concept Of Maximum Stream Depletion Rate For Leaky Aquifers In Alluvial Valleys" By Vitaly A. Zlotnik, Vitaly A. Zlotnik

Department of Earth and Atmospheric Sciences: Faculty Publications

In the paper ‘‘A concept of maximum stream depletion rate for leaky aquifers in alluvial valleys’’ by Vitaly A. Zlotnik (Water Resources Research, 40(6), W06507, doi:10.1029/2003WR002932, 2004), equations (24), (25), (A11), and (A12) were published with typographical errors. The correct equations are published below.


The Use Of Bauxite Residue To Control Diffuse Phosphorus Pollution In Western Australia – A Win-Win-Win Outcome, Robert Summers, Mark Rivers, Martin Clarke Aug 2004

The Use Of Bauxite Residue To Control Diffuse Phosphorus Pollution In Western Australia – A Win-Win-Win Outcome, Robert Summers, Mark Rivers, Martin Clarke

Conference papers and presentations

The Department of Agriculture, Western Australia has been working with Alcoa World Alumina Australia Ltd for more than ten years investigating the potential to use bauxite refining residues as soil amendments for the poor, acidic, sandy soils of the Swan Coastal Plain in south west Australia. Regional waterways, especially the Peel Inlet and Harvey Estuary, have historically been susceptible to nuisance algal blooms fed by phosphorus in run-off from farmland and urban areas. Extensive laboratory, field and catchment-scale trials have shown the ability of soil amendment with fine bauxite refining residue (now trademarked in this context as Alkaloam™) to reduce …


Lithium Abundance And Isotope Systematics Of Forearc Serpentinites, Conical Seamount, Mariana Forearc: Insights Into The Mechanics Of Slab-Mantle Exchange During Subduction, Laurie D. Benton, Jeffrey G. Ryan, Ivan P. Savov Aug 2004

Lithium Abundance And Isotope Systematics Of Forearc Serpentinites, Conical Seamount, Mariana Forearc: Insights Into The Mechanics Of Slab-Mantle Exchange During Subduction, Laurie D. Benton, Jeffrey G. Ryan, Ivan P. Savov

Geology Faculty Publications

[1] Variable lithium contents and contrasting Li isotopic signatures are evident in the serpentininite muds and clasts extruded at Conical Seamount in the Mariana forearc. The muds have high Li contents compared to mantle values (3–7 ppm) and a mean δ7Li value of ∼+6‰. The clasts are generally lower in Li, and δ7Li varies from −6‰ to +10‰, with higher δ7Li correlating broadly to higher lithium contents. The diverse δ7Li in the serpentinite clasts suggests Li exchanges between mantle rocks and evolving slab‐derived fluids from different depths, producing a subarc mantle that is zoned in terms of Li abundances and …


Southern Cascadia Episodic Slow Earthquakes, Walter Szeliga, Timothy I. Melbourne, M. Meghan Miller, Marcelo Santillan Aug 2004

Southern Cascadia Episodic Slow Earthquakes, Walter Szeliga, Timothy I. Melbourne, M. Meghan Miller, Marcelo Santillan

Faculty Scholarship for the Cascadia Hazards Institute

Continuous GPS and seismic data from northern California show that slow earthquakes periodically rupture the Gorda-North America plate interface within southern Cascadia. On average, these creep events have occurred every 10.9±1.2 months since at least 1998. Appearing as week-long GPS extensional transients that reverse secular forearc contraction, the data show a recurrence interval 22% shorter than slow events recognized to the north. Seismic tremor here accompanies the GPS reversals, correlated across as many as 5 northern California seismometers. Tremor occurs sporadically throughout the year, but increases in duration and intensity by a factor of about 10 simultaneous with the GPS …


Southern Cascadia Episodic Slow Earthquakes, Walter Szeliga, Timothy I. Melbourne, M. Meghan Miller, V. Marcelo Santillan Aug 2004

Southern Cascadia Episodic Slow Earthquakes, Walter Szeliga, Timothy I. Melbourne, M. Meghan Miller, V. Marcelo Santillan

All Faculty Scholarship for the College of the Sciences

Continuous GPS and seismic data from northern California show that slow earthquakes periodically rupture the Gorda‐North America plate interface within southern Cascadia. On average, these creep events have occurred every 10.9 ± 1.2 months since at least 1998. Appearing as week‐long GPS extensional transients that reverse secular forearc contraction, the data show a recurrence interval 22% shorter than slow events recognized to the north. Seismic tremor here accompanies the GPS reversals, correlated across as many as 5 northern California seismometers. Tremor occurs sporadically throughout the year, but increases in duration and intensity by a factor of about 10 simultaneous with …


Numerical Modeling Of Geophysical Granular Flows: 2. Computer Simulations Of Plinian Clouds And Pyroclastic Flows And Surges, Sebastien Dartevelle, William I. Rose, John Stix, Karim Kelfoun, James W. Vallance Aug 2004

Numerical Modeling Of Geophysical Granular Flows: 2. Computer Simulations Of Plinian Clouds And Pyroclastic Flows And Surges, Sebastien Dartevelle, William I. Rose, John Stix, Karim Kelfoun, James W. Vallance

Department of Geological and Mining Engineering and Sciences Publications

Geophysical granular flows display complex nonlinear, nonuniform, and unsteady rheologies, depending on the volumetric grain concentration within the flow: kinetic, kinetic-collisional, and frictional. To account for the whole spectrum of granular rheologies (and hence concentrations), we have used and further developed for geophysical-atmospheric applications a multiphase computer model initially developed by U.S. Department of Energy laboratories: (Geophysical) Multiphase Flow with Interphase Exchange. As demonstrated in this manuscript, (G)MFIX can successfully simulate a large span of pyroclastic phenomena and related processes: plinian clouds, pyroclastic flows and surges, flow transformations, and depositional processes. Plinian cloud simulations agree well with the classical plume …


Scattering Matrices Of Volcanic Ash Particles Of Mount St. Helens, Redoubt, And Mount Spurr Volcanoes, O. Muñoz, H. Volten, J. W. Hovenier, B. Veihelmann, W. J. Van Der Zande, L. B. F. M. Waters, William I. Rose Aug 2004

Scattering Matrices Of Volcanic Ash Particles Of Mount St. Helens, Redoubt, And Mount Spurr Volcanoes, O. Muñoz, H. Volten, J. W. Hovenier, B. Veihelmann, W. J. Van Der Zande, L. B. F. M. Waters, William I. Rose

Department of Geological and Mining Engineering and Sciences Publications

We present measurements of the whole scattering matrix as a function of the scattering angle at a wavelength of 632.8 nm in the scattering angle range 3°–174° of randomly oriented particles taken from seven samples of volcanic ashes corresponding to four different volcanic eruptions: the 18 May 1980 Mount St. Helens eruption, the 1989–1990 Redoubt eruption, and the 18 August and 17 September 1992 Mount Spurr eruptions. The samples were collected at different distances from the vent. The samples studied contain large mass fractions of fine particles and were chosen to represent ash that could remain in the atmosphere for …