Stylolites in twelve stratigraphic sections of the Salem Limestone, distributed throughout the Illinois Basin, provide clues to their origin and development. Chemical and X-ray diffraction analyses reveal that stylolite seam material contains organic matter and clay minerals too sparse or absent in the host limestone to be considered solely as insoluble residue. Stylolite distribution in various lithofacies suggests that stylolites develop along thin sedimentary layers rich in organic matter and clay minerals. Stylolite density (vertical distribution) mimics the distribution of organic-rich sedimentary layers: sparse but thick in grainstone, and abundant but thin in packstone and wackestone. Many stylolites grade laterally into organic-rich layers, or hummocky seams. Thicknesses of stylolite caps and hummocky seams are approximately equal in the same host rock, but hummocky seams tend to be more laterally continuous. Stylolite density in packstone increases with burial depth, whereas hummocky seam density decreases. Hummocky seam thickness does not change with depth. Stylolite column height in grainstone, which is sparse in hummocky seams, increases with depth, whereas stylolite density does not increase. This list of observations supports the hypothesis that stylolites develop along pre-existing, organic-rich layers, or hummocky seams, rather than nucleating in pure host rock and creating organic-rich seams as accumulations of insoluble residue. Volumetric calculations indicate that the contribution of stylolites to pore-filling cement is 5 to 25 percent throughout the Illinois Basin.
In the 1990's the incidence of eating disorders among college aged females had increased (Johnston & Christropher, 1991) with specific concern for female college athletes. A 1992 NCAA study found that 70% of responding institutions reported at least one case of an eating disorder with the highest prevalence in gymnastics, cross country, swimming, and track (Dick, 1993).
The Aspen Grove landslide, central Utah, occurred in older landslide debris. The debris is about 6-15 meters thick, and consists of medium- to high-plasticity clays and silty clays. Persistent landslide structures, including toes, hollows, and flank ridges, outline dimly preserved landslide masses in the older debris.
The temporal subdomain method based on the Ritz-Galerkin method is investigated as a method for the solution of space-time dependent neutron dynamics equations. In the temporal subdomain finite element method, the time domain is divided into subdomains and within each subdomain the unknown coefficients of the time dependent trial functions are determined by making the residual of an appropriate functional orthogonal to the step function.
Filtration theory was developed by engineers to model the removal of particulate matter from industrial gases. Recently, it has been used by biologists and paleo-biologists to model the capture of food particles by filter feeding organisms. The purpose of this study was to test paleosynecologic (biofacies-level) and paleoautecologic (species-level) models of crinoid distribution utilizing filtration theory. These models were tested by analyzing the crinoid faunas of three transgressive-regressive sequences from the Upper Pennsylvanian Lansing Group of midcontinent North America.
Roots of white ash have a better configuration than roots of sugar maple for anchoring shallow colluvium against landsliding on hillslopes along the Ohio River and its tributaries in southwestern Ohio. The landslides are in a shallow layer of colluvium, about one meter thick, overlying shale and limestone bedrock. The sliding hillsides range in slope angle from 16 to 36 degrees and the roots which penetrate shear surfaces are anchored in the weathered bedrock and help to hold landmasses in place. The hillsides are covered by a mesophytic forest, locally known as a ravine community, dominated by white ash, sugar maple and sweet buckeye. Sugar maple is the most common species on the landslides; its roots do not penetrate the soil as deeply as the roots of the white ash.