P- and S- wave velocities of consolidated sediments from a seafloor seismic survey in the North Celtic Sea Basin, offshore Ireland

A geophysical survey was conducted over a hydrocarbon prospect in the North Celtic Sea Basin using a small array of ocean-bottom seismographs (OBSs). The purpose of this study was to determine the ratio of (P) compressional- to (S) shear-wave velocity of consolidated sedimentary rocks in order to constrain possible subsurface variations in pore-fluid content. The ratio of VP and VS- is known to be particularly sensitive to lithology, porosity and pore-fluid content, making it a useful parameter for evaluating hydrocarbon prospects. OBSs offer a relatively cheap and time-effective means of acquiring multi-component data compared with ocean-bottom cables. In this contribution, we demonstrate the ability of an OBS survey comprising three pairs of two OBSs spaced at 1.6 km to recover lateral variations in the VP/VS ratio. A key requirement of this type of study is that S-waves will be generated by mode conversions in the subsurface, since they cannot be generated in nor travel through fluids. In this survey, the contrast in physical properties of the hard seabed of the North Celtic Sea Basin provided a means of generating converted S-waves. Two-dimensional ray-tracing and forward modeling was used to create both VP and VS models along a profile crossing the Blackrock prospect in the North Celtic Sea Basin. These models comprise four layers and extend to a maximum depth of 1.1 km. The observed northward decrease in the VP/VS ratio at depths of 500-1000 m below the seafloor in the study area is interpreted to represent lateral variation in the amount of gas present in the pore space of Upper Cretaceous chalks and shales overlying the prospective reservoir

Using goats to control weeds

Feral goats are common in the woodland and tall shrubland areas of arid Australia. They survive and reproduce despite regular shooting, capture and droughts. These goats are considered vermin in Western Australia because of their competition with sheep for forage and their reputation as destroyers of vegetation. Research elsewhere, however, has indicated that it is only the uncontrolled grazing by large numbers of goats that causes degradation, in the same way that uncontrolled grazing by sheep can cause erosion. To some people, however, feral goats are a valuable source of income. They have the potential for meat sales, and they form the basis of breeding programmes for mohair and cashmere. Another potential which is only now being properly studied is the use of goats to eliminate or at least reduce unwanted vegetation

The origin of the ninetyeast ridge and the northward motion of India, based on DSDP paleolatitudes

Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution January, 1977This thes is is a collection of papers on the paleomagnetics of samples from several Deep Sea Drilling Project (DSDP) sites in the Indian Ocean. These papers present the basic paleomagnetic data, discuss the statistical methods for analyzing such data from DSDP cores, and examine the implications of the paleolatitudes for the origin of the Ninetyeast Ridge and the northward motion of India. Rarely do DSDP paleolatitudes approach the reliability of good continental pole positions. However, the reliability of such paleolatitudes can be markedly improved by using comparisons with paleolatitudes of different ages from the same site, paleolatitudes of similar ages from different sites on the same plate, estimates of paleolatitude from the skewness of marine magnetic anomalies, and continental paleopole. positions. Using such comparisons, a new paleomagnetic pole of upper Cretaceous age has been defined for the Pacific plate. A middle Cretaceous pole has been defined for the Wharton Basin plate, and it suggests that there may have been left lateral motion between Australia and the Wharton Basin. Paleolatitudes from the Ninetyeast Ridge are consistent with the pole position for the Deccan Traps. These data indicate that India and the Ninetyeast Ridge moved northwards with respect to the South Pole at 14.9 ± 4.5 cm/yr from 70 to 40 mybp and at 5.2 ± .8 cm/yr from 40 mybp until the present. However, when this paleomotion is compared to the Australian paleomagnetic data (by removing the relative motion components), a major inconsistency appears between 40 and 50 mybp. The Australian data indicate that India should be 13° further north than the positions implied by the Ninetyeast Ridge data. Basal paleolatitudes on the Ninetyeast Ridge indicate that its volcanic source was approximately fixed in latitude near 50°S, supporting the hypothesis that the ridge is the trace of the Kerguelen hotspot on the northward moving Indian plate. There is considerable geologic evidence in favor of such an hypothesis, and there is none to contradict it.National Science Foundation (Grant DES-74-22552)

The evolution of the Nares Strait lineament and its relation to the Eurekan orogeny

If one accepts that the Labrador Sea was closed in Early Cretaceous time, then this assumption creates extra space northwest of Greenland. Where Ellesmere Island lay within it relative to Greenland and also to North America becomes a major problem in geological interpretation. Whatever solution is chosen creates conflicts with the current interpretations of the geology of the eastern Sverdrup Basin and/or the geology of Nares Strait. The main elements of the tectonic model presented herein are: 1) Early to Middle Cretaceous: incipient rifting in the Labrador Sea terminated in an RRR triple junction north of Bylot Island and established the Nares Strait and Lancaster Sound lineaments; 2) Late Cretaceous to Early Paleocene: Greenland and Ellesmere Island rotated together counter-clockwise relative to North America, causing crustal shortening in the Sverdrup Basin (the first phase of the Eurekan orogeny); 3) Late Paleocene to Early Oligocene: responding to a new pole of rotation, Greenland moved left-laterally relative to Ellesmere Island along the Wegener Transform Fault; 4) Middle Oligocene: Greenland and Ellesmere Island moved northwestwards some 40-50 km (the main phase of the Eurekan orogeny); 5) Middle Oligocene to Present: compressive stresses relaxed followed by rapid subsidence of all basins. This model requires that the Early Cretaceous Sverdrup Basin was much wider than today. An analogy is drawn with the thin-skinned tectonic model for the southern Appalachians as a possible mechanism to reconcile this requirement with the known geology. As major lateral Tertiary motion on the Wegener Fault is at oddswith the geological interpretations across Nares Strait, this model suggests that either an alternative geological interpretation of Nares Strait (perhaps in the context of a fault zone) be found, alternative locations to accommodate the motion be found, or else the currently accepted tectonic history of the North Atlantic is seriously in error

Reconstruction Of Neets'Aii Gwich'In Land Use: A Methodological Study.

Thesis (M.A.) University of Alaska Fairbanks, 1995This thesis attempts to determine to what extent land use patterns for the Neets'aii Gwich'in of Alaska can be spatially reconstructed from existing sources. Written narratives are reviewed, such as those related by explorers, missionaries, traders and prospectors, for information on land use. Also reviewed are data that give a broad array of subsistence, demographic, geographical or other relevant information concerning land use, including biological and geological reports, economic studies, census reports, Neets'aii Gwich'in oral narratives, archaeological studies, ethnographic studies, place name studies and maps, and land use and occupancy studies. Methodological models for gathering land use data are reviewed to establish a foundation from which the land use data discussed in this thesis can be compared. Finally, an analysis of the extent to which Neets'aii Gwich'in land use can be reconstructed using historic sources is applied to various conceptual levels of understanding Northern hunter and gatherer land use. <p

Symbiotic modeling: Linguistic Anthropology and the promise of chiasmus

Reflexive observations and observations of reflexivity: such agendas are by now standard practice in anthropology. Dynamic feedback loops between self and other, cause and effect, represented and representamen may no longer seem surprising; but, in spite of our enhanced awareness, little deliberate attention is devoted to modeling or grounding such phenomena. Attending to both linguistic and extra-linguistic modalities of chiasmus (the X figure), a group of anthropologists has recently embraced this challenge. Applied to contemporary problems in linguistic anthropology, chiasmus functions to highlight and enhance relationships of interdependence or symbiosis between contraries, including anthropology’s four fields, the nature of human being and facets of being human

Modelling the way mathematics is actually done

Whereas formal mathematical theories are well studied, computers cannot yet adequately represent and reason about mathematical dialogues and other informal texts. To address this gap, we have developed a representation and reasoning strategy that draws on contemporary argumentation theory and classic AI techniques for representing and querying narratives and dialogues. In order to make the structures that these modelling tools produce accessible to computational reasoning, we encode representations in a higherorder nested semantic network. This system, for which we have developed a preliminary prototype in LISP, can represent both the content of what people say, and the dynamic reasoning steps that move from one step to the next

A group of new buildings for Baldpate, Inc. : a private psychiatric sanitarium in Georgetown, Massachusetts

Thesis (M.Arch.) Massachusetts Institute of Technology. Dept. of Architecture, 1947.Accompanying drawings held by MIT Museum.Bibliography: leaf 48.by John W. Peirce.M.Arch