The Valley and Ridge Province of eastern Pennsylvania—stratigraphic and sedimentologic contributions and problems

Many contributions that have led to a better understanding of Appalachian geology have resulted directly from work in the folded Appalachian Mountain and Great Valley sections of the Valley and Ridge physiographic province of eastern Pennsylvania. Disagreements have been common since H.D. Rogers first described the geology of the area in 1858. Many differing opinions still exist regarding the stratigraphy, structural geology, geomorphology, and glacial geology. The rocks in the area, which range from Middle Ordovician to Late Devonian in age, are more than 25000 feet (7620 m) thick. This diversified group of sedimentary rocks was deposited in many different environments, ranging from deep sea, through neritic and tidal, to alluvial. In general, the Middle Ordovician through Lower Devonian strata are a sedimentary cycle related to the waxing and waning of Taconic tectonism. The sequence began with a greywacke-argillite suite (Martinsburg Formation) representing synorogenic basin deepening. This was followed by basin filling and pro-gradation of a sandstone-shale clastic wedge (Shawangunk Formation and Bloomsburg Red Beds) derived from the erosion of the mountains that were uplifted during the Taconic orogeny. The sequence ended with deposition of many thin units of carbonate, sandstone, and shale on a shelf marginal to a land area of low relief. Another tectonic-sedimentary cycle, related to the Acadian orogeny, began with deposition of Middle Devonian rocks. Deep-water shales (Marcellus Shale) preceded shoaling (Mahantango Formation) and turbidite sedimentation (Trimmers Rock Formation) followed by another molasse (Catskill Formation).     

Heat transfer and thermal boundary layers in high amplitude annulus waves

Abstract

The heat transfer by a rotating, differentially-heated annulus of fluid is measured throughout the high amplitude wave regime. Only Δr_w T was varied (although v(T₁₅ ).K(T₁₅ ) varied by 46%), and it is found that Nu = C₁(λ)Ra^? away from the symmetry and low amplitude to wave transition curves and this is independent of ω. (λ is the wavelength.) On the wave side of these transition curves a region exists in which Nu (symmetry) λ Nu λ C₁(λ)Ra^?. The local heat transfer rate also varies strongly with wave phase.

Using a selection of measured internal thermal fields in the steady, high amplitude wave regime, the side-wall thermal boundary layer structure is examined. It is found that Nu, = C₂·Gr₂ ^A2; both C ₂ and A ₂ are independent of ω and λ to first order. For the time mean profiles, A ₂ ≈ 0.25; in the high heat transfer portion of the wave A ₂ < ¼ and in the low heat transfer portion of the wave A ₂ > ?. These relations hold over most of the vertical extent of the side walls. The deviations of the boundary layers from the above behavior which occur on the remainder of the walls is illustrated. The average thicknesses of the wall boundary layers ∞ Ra^?¼ except in that phase of the wave in which the wall to mid-gap temperature difference is the largest.     

An evaluation of flow-stratified sampling for estimating suspended sediment loads

Flow-stratified sampling is a new method for sampling water quality constituents such as suspended sediment to estimate loads. As with selection-at-list-time (SALT) and time-stratified sampling, flow-stratified sampling is a statistical method requiring random sampling, and yielding unbiased estimates of load and variance. It can be used to estimate event yields or to estimate mean concentrations in flow classes for detecting change over time or differences from water quality standards. Flow-stratified sampling is described and its variance compared with those of SALT and time-stratified sampling. Time-stratified sampling generally gives the smallest variance of the three methods for estimating storm yields. Flow-stratified sampling of individual storms may fail to produce estimates in some short-lived strata because they may have sample sizes of zero. SALT will tend to give small samples and relatively high variances for small stroms. For longer and more complex hydrographs, having numerous peaks, flow-stratified sampling gives the lowest variance, and the SALT variance is lower than that of time-stratified sampling unless the sample size is very large. A desirable feature of flow-stratified sampling is that the variance can be reduced after sampling by splitting strata, particularly high flow strata that have been visited just once, and recalculating the total and variance. SALT has the potential to produce the lowest variance, but cannot be expected to do so with an auxiliary variable based on stage.     

Syntectonic vein development in a thrust sheet from the external French Alps

The geometry and age relations of syntectonic veins within calcareous rocks of one imbricate sheet within a thrust belt in the external French Alps, are described.The earliest veins developed during the main ductile deformation by cleavage-parallel extension. The majority of the syntectonic veins developed towards the end of the deformation, and after the formation of second folds. They include a conjugate set of normal shears, an abundant set of upright extension veins, and en echelon sets.The dominantly simple shear strain making up the main ductile phase of deformation occurred by a mechanism of grain to grain pressure solution. The stretching lineation records the overall direction of thrust sheet movement. A change in the microchemical mechanism of pressure solution is thought to have caused the change from first to second phase deformation as recorded by slaty cleavage and crenulation folds in the field. From the shear and vein geometries, directions of principal stress have been inferred. The directions rotated throughout the deformation, the maximum principal stress being inclined to bedding during simple shear strain, becoming normal to bedding during the phase of abundant vein growth, and becoming vertical at the very end of the deformation.     

MAPPING FROM AN AUTOMATED DISPLAY SYSTEM*

This paper outlines recent developments in computer mapping and points out its importance for visualizing contents of geographic information systems. The authors present an integrated system of mapping packages and spatial-data files. Map examoles generated with this system are used to illustrate characteristics of various computer-mapping methods. The diversity of displays created from a single set of data demonstrates that mapping from automated display systems requires the user to take some decisions which have to be based on an understanding of the phenomena displayed, of cartographic communication, and of technical aspects of automated map processing.