Mining Geology of the Lower Elkhorn Coal

The Lower Elkhorn (and its equivalents) is one of the leading producers of coal in the Eastern Kentucky Coal Field with 12 to 18 million short tons of annual production between 1974 and 1996, according to the Kentucky Department of Mines and Minerals. Stratigraphically, the coal occurs in the lower part of the Pikeville Formation of the Breathitt Group (Fig. 1), which was previously part of the Breathitt Formation (Chesnut, 1992). The coal occurs from 150 to 300 ft above the base of a thick coarsening-upward sequence containing the Betsie Shale and from 250 to 450 ft beneath the base of the Kendrick Shale. The Lower Elkhorn coal is overlain by laterally variable roof rocks, which control roof conditions during underground mining. Figure 2 summarizes the mining geology of the Lower Elkhorn coal. Features shown in the figure are discussed elsewhere in this chart. Splitting and thickness variation are discussed in Thacker and others (1998)

Mining Geology of Coals in Western Kentucky

Each of the most heavily mined coal seams in the Western Kentucky Coal Field, as indicated by analyses, mine visits, and discussions with mine inspectors and engineers, has its own roof and floor characteristics. Also, because roof rocks above several of the seams are laterally continuous (especially in the Carbondale Formation), roof characteristics related to rock type are often widespread and continuous between mines. This chart discusses the mining geology of three western Kentucky coal beds, highlighted on the stratigraphic column shown in Figure 1. Additional mining obstacles that can affect all coal beds and roof strata are (1) tectonic faulting, which is prevalent in western Kentucky, (2) fractures related to low cover and past mining, and (3) fractures related to the regional tectonic stress field

Acitretin for the Treatment of Recalcitrant Plantar Warts

Plantar warts caused by human papilloma virus (HPV)may be challenging to treat when conventionalmodalities fail. We report a case of severely recalcitrantplantar warts, successfully treated with oral acitretinand topical 40% urea cream

Geology and Stratigraphy of the Western Kentucky Coal Field

The Pennsylvanian rocks of the Western Kentucky Coal Field produce between 40 and 55 million tons of coal a year from as many as 45 coal seams; however, three seams produce more than 75 percent of the total. In addition, Pennsylvanian strata contain numerous oil and natural gas reservoirs, tar-sand reservoirs, and industrial minerals. Pennsylvanian sandstones are also some of the most important bedrock aquifers in the coal field. Because of the economic importance of the Pennsylvanian strata to the region and the Commonwealth as a whole, a better understanding of these rocks is needed. This description of the nomenclature of Pennsylvanian strata in the Western Kentucky Coal Field also provides information on their mineral resources and geology. New stratigraphic names, based on regional agreements among the state geological surveys of Kentucky, Illinois, and Indiana, are also presented

Total Coal Thickness of the Fire Clay and Fire Clay Rider Coals in Eastern Kentucky

This map is one of a series that shows the regional characteristics of the Fire Clay coal zone. The maps were prepared as part of the U.S. Geological Survey\u27s National Coal Assessment Program, which compiles regional maps and databases that provide a comprehensive assessment of the most important coal beds in the nation. Within the zone, the Fire Clay coal is the most economically important bed and is one of the leading producers in the state of Kentucky. It is known for a persistent flint-clay parting that is believed to be of volcanic origin. This map represents the total coal thickness, minus partings, of the Fire Clay and Fire Clay rider coals for the eastern Kentucky region

Coal Resources of the Fire Clay Coal Zone in Eastern Kentucky

This chart is one of a series that shows the regional characteristics of the Fire Clay coal zone. The maps and charts were prepared as part of the U.S. Geological Survey\u27s National Coal Assessment Program, which compiles regional maps and databases that provide a comprehensive assessment of the most important coal beds in the nation. Within this coal zone, the Fire Clay coal is the most economically important bed and is one of the leading producers in the state of Kentucky. The Fire Clay coal contains a flint-clay parting that is believed to be of volcanic origin. The widespread occurrence of this parting aids in correlation, and therefore the Fire Clay coal is a key marker bed in the region. This chart describes the distribution of data used for the coal assessment, generalized mined-out areas in relation to coal thickness, geologic structure of the bed, and coal-resource estimates. Coal thickness for the Fire Clay and Fire Clay rider beds is presented in Kentucky Geological Survey Map and Chart Series 5 (series 12)

Geology of the Fire Clay Coal in Part of the Eastern Kentucky Coal Field

Coal beds mined in Kentucky often are not laterally continuous in thickness, quality, or roof condition. Regional and local variation is common. Because thickness, quality, and roof conditions are the result of geologic processes that were active when the coal was deposited as a peat swamp, a better understanding of the relationships between geology and major coal resources can aid in identifying geologic trends, which can be extrapolated beyond areas of present mining. The focus of this study is on the Fire Clay (Hazard No. 4) coal, one of the leading producers in the Eastern Kentucky Coal Field with 20 million short tons of annual production. More than 3,800 thickness measurements, highwall and outcrop descriptions, borehole and geophysical-log descriptions, and proximate analyses from 97 localities were used in conjunction with previous palynologic and petrographic studies to investigate the geology of the Fire Clay coal in a 15-quadrangle area of the Eastern Kentucky Coal Field. The Fire Clay coal is commonly separated into two distinct layers or benches by a flint-clay and shale parting called the “jackrock parting” by miners. Maps of coal benches above and below the parting show that the lower bench is limited in extent and variable in thickness. In contrast, the coal above the jackrock parting occurs across most of the study area and is characterized by rectangular patterns of coal thickness. Multiple coal benches resulted from the accumulation of multiple peat deposits, each with different characteristics. The lower bench of the coal was deposited when a peat accumulated above an irregular topographic surface. Because the peat was being deposited at or below the water table, it was often flooded by sediment from lateral sources, resulting in moderate to locally high ash yields. This peat was drowned and then covered by volcanic ash, which formed the flint clay in the jackrock parting. The upper coal bench accumulated above the ash deposit, after irregularities in the topography had been filled. The relatively flat surface allowed the swamps to spread outward and dome upward above the water table in some areas. Doming of the peat resulted in areas of coal with generally low ash yields and sulfur contents. Sharp, angular changes in the upper coal bench are inferred to represent subtle fault influence on upper peat accumulation. The upper peat was buried by a series of river channels, which were bounded by levees, flood plains, and elongate bays. Several of the rivers eroded through the Fire Clay peats, forming cutouts in the coal. These cutouts often follow orientations similar to the angular trends of coal thinning, suggesting a relationship that can be extended beyond the present limits of mining. Also, additional peat swamps accumulated above the levees and flood plains bounding the channels. Along the thinning margins of these deposits, the peats came near or merged with the top of the Fire Clay coal, resulting in local areas of increased coal thickness. Rider coal benches exhibit high to moderate sulfur contents and ash yields, so that although they may increase coal thickness, total coal quality generally decreases where riders combine with the Fire Clay coal

Internal C-C Bond Rotation in Photoisomers of α-Bisimines: A Light-Responsive Two-Step Molecular Speed Regulator Based on Double Imine Photoswitching

Benzil-based α-bisimines are implemented as photoswitches for the construction of a speed-regulating molecular device, in which, by application of light, three different states may be addressed, showing distinct frequencies of internal C–C bond rotation, spanning 12 orders of magnitude. Bond rotation barriers were determined experimentally and elucidated by DFT-methods

Calix[4]pyrrolato Aluminate Catalyzes the Dehydrocoupling of Phenylphosphine Borane to High Molar Weight Polymers

High molar weight polyphosphinoboranes represent materials with auspicious properties, but their preparation requires transition metal-based catalysts. Here, calix[4]pyrrolato aluminate is shown to induce the dehydropolymerization of phosphine boranes to high molar mass polyphosphinoboranes (up to Mn=43 000 Da). Combined GPC and 31P DOSY NMR spectroscopic analyses, quantum chemical computations, and stoichiometric reactions disclose a P−H bond activation by the cooperative action of the square-planar aluminate and the electron-rich ligand framework. This first transition metal-free catalyst for P−B dehydrocoupling overcomes the problem of residual d-block metal impurities in the resulting polymers that might interfere with the reproducibility of the properties for this emerging class of inorganic materials