428 research outputs found
Crust and upper mantle structure in the region of Barbados and the Lesser Antilles
The Lesser Antilles form one of only two island arcs that occur in the Atlantic Ocean. Bathymetric, gravity, magnetic, and seismic reflection data were collected by HMS HECLA during 1971 in an area bounded by latitudes 12 54β N and 13 54' N, and longitudes 57 W and 61 10' W, including the islands of St. Lucia, St. Vincent, and Barbados. These data are reduced and interpreted in conjunction with seismic refraction data from an experiment run in 1972 and data from other published and unpublished sources. The structure of the upper sedimentary layers is derived from the seismic reflection records. The crustal structure is modelled two dimensionally using a non-linear optimisation technique to fit the observed gravity and seismic refraction data. The island arc and the Barbados Ridge are examined in detail, and the nature of a ridge running eastward from St. Lucia into the Atlantic Ocean basin is investigated. Magnetic anomalies are treated by direct modelling, magnetic to gravity transformation, and analysis of the power spectrum. The seismicity of the eastern Caribbean is considered with respect to possible plate motions, and maps of focal depth and energy release are presented. The mechanism and causes of subduction beneath the Lesser Antilles are discussed. The possible gravity anomaly caused by subducted lithosphere is estimated and its effect on the determination of the crustal structure examined. The influence of the relative motions between the North and South American plates on the development of the Caribbean and the Lesser Antilles is studied. Some ideas on the origin and growth of the Barbados Ridge and the island arc are put forward. Geophysical data profiles, and computer programs for reduction and interpretation of data are presented in appendices
ΠΠ΅ΡΠ΅Π½ΠΈΠ΅ ΠΈ ΠΏΡΠΎΡΠΈΠ»Π°ΠΊΡΠΈΠΊΠ° Π³ΡΠΈΠΏΠΏΠ° Ρ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π½ΠΈΠ΅ΠΌ Π±ΠΈΠΎΡΠ»Π°Π²ΠΎΠ½ΠΎΠΈΠ΄ΠΎΠ²
ΠΠ° ΠΎΡΠ½ΠΎΠ²Π°Π½ΠΈΠΈ Π°Π½Π°Π»ΠΈΡΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΠΎΠ±Π·ΠΎΡΠ° Π»ΠΈΡΠ΅ΡΠ°ΡΡΡΡ ΠΏΡΠ΅Π΄ΡΡΠ°Π²Π»Π΅Π½Ρ Π΄Π°Π½Π½ΡΠ΅ ΠΎΠ± ΡΡΡΠ΅ΠΊΡΠΈΠ²Π½ΠΎΡΡΠΈ ΠΈ Π±Π΅Π·ΠΎΠΏΠ°ΡΠ½ΠΎΡΡΠΈ ΠΏΡΠΈΠΌΠ΅Π½Π΅Π½ΠΈΡ Π±ΠΈΠΎΡΠ»Π°Π²ΠΎΠ½ΠΎΠΈΠ΄ΠΎΠ² (Π»Π΅ΠΊΠ°ΡΡΡΠ²Π΅Π½Π½ΡΠΉ ΠΏΡΠ΅ΠΏΠ°ΡΠ°Ρ ΠΡΠΎΡΠ΅ΡΠ»Π°Π·ΠΈΠ΄ Π² Π²ΠΈΠ΄Π΅ ΠΊΠ°ΠΏΠ΅Π»Ρ ΠΈ ΡΠΈΡΠΎΠΏ ΠΠΌΠΌΡΠ½ΠΎΡΠ»Π°Π·ΠΈΠ΄) Π² ΡΡ
Π΅ΠΌΠ΅ Π»Π΅ΡΠ΅Π½ΠΈΡ ΠΈ ΠΏΡΠΎΡΠΈΠ»Π°ΠΊΡΠΈΠΊΠΈ Π³ΡΠΈΠΏΠΏΠ°. ΠΡΠΎΠ°Π½Π°Π»ΠΈΠ·ΠΈΡΠΎΠ²Π°Π½Π½ΡΠ΅ Π² ΡΡΠΎΠΉ ΡΠ°Π±ΠΎΡΠ΅ Π½Π°ΡΡΠ½ΡΠ΅ ΠΏΡΠ±Π»ΠΈΠΊΠ°ΡΠΈΠΈ ΡΠ²ΠΈΠ΄Π΅ΡΠ΅Π»ΡΡΡΠ²ΡΡΡ ΠΎΠ± ΡΡΠΈΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈ ΠΈ ΠΏΠ°ΡΠΎΠ³Π΅Π½Π΅ΡΠΈΡΠ΅ΡΠΊΠΈ ΠΎΠ±ΠΎΡΠ½ΠΎΠ²Π°Π½Π½ΠΎΠΌ Π½Π°Π·Π½Π°ΡΠ΅Π½ΠΈΠΈ ΠΡΠΎΡΠ΅ΡΠ»Π°Π·ΠΈΠ΄Π°, ΠΌΠ΅Ρ
Π°Π½ΠΈΠ·ΠΌ ΠΏΡΠΎΡΠΈΠ²ΠΎΠ³ΡΠΈΠΏΠΏΠΎΠ·Π½ΠΎΠ³ΠΎ Π΄Π΅ΠΉΡΡΠ²ΠΈΡ ΠΊΠΎΡΠΎΡΠΎΠ³ΠΎ ΠΎΡΠ½ΠΎΠ²Π°Π½ Π½Π° ΡΠ³Π½Π΅ΡΠ΅Π½ΠΈΠΈ ΡΠ΅ΠΏΡΠΎΠ΄ΡΠΊΡΠΈΠΈ Π²ΠΈΡΡΡΠΎΠ² Π³ΡΠΈΠΏΠΏΠ°, Π² ΡΠΎΠΌ ΡΠΈΡΠ»Π΅ ΠΏΠ°Π½Π΄Π΅ΠΌΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΡΡΠ°ΠΌΠ° A/FM/1/47/H1N1/ Π·Π° ΡΡΠ΅Ρ ΠΌΠ΅Ρ
Π°Π½ΠΈΠ·ΠΌΠ° ΠΈΠ½Π³ΠΈΠ±ΠΈΡΠΎΠ²Π°Π½ΠΈΡ Π½Π΅ΠΉΡΠ°ΠΌΠΈΠ½ΠΈΠ΄Π°Π·Π½ΠΎΠΉ Π°ΠΊΡΠΈΠ²Π½ΠΎΡΡΠΈ, ΠΈΠ½Π΄ΡΠΊΡΠΈΠΈ ΡΠΈΠ½ΡΠ΅Π·Π° ΠΈΠ½ΡΠ΅ΡΡΠ΅ΡΠΎΠ½Π°
Sovereignty in English Political Thought 1576-1628
This thesis aims for the most part to give an updated analysis of the reception of Bodin's theory of sovereignty into English political thought before the personal rule of Charles I. The relevance of such a study for modern constitutionalism is in the delineation, both of Bodin's original concept, and of the versions of this concept adopted in England long before the time of Blackstone. While it is to be hoped that this elucidation will aid in the understanding of sovereignty today, care must he taken to recognise the limits of such studies. The elements of parliamentary sovereignty which present writers discuss include many which came into being centuries after Bodin's time, so that what we can expect to see in this early period is only a barebones theory of sovereignty. But it is also a minimalist statement of the architecture of the modern State in that it expresses a legal view of political supremacy
Resistivity image beneath an area of active methane seeps in the west Svalbard continental slope
The Arctic continental margin contains large amounts of methane in the form of methane hydrates. The west Svalbard continental slope is an area where active methane seeps have been reported near the landward limit of the hydrate stability zone. The presence of bottom simulating reflectors (BSRs) on seismic reflection data in water depths greater than 600 m suggests the presence of free gas beneath gas hydrates in the area. Resistivity obtained from marine controlled source electromagnetic (CSEM) data provides a useful complement to seismic methods for detecting shallow hydrate and gas as they are more resistive than surrounding water saturated sediments. We acquired two CSEM lines in the west Svalbard continental slope, extending from the edge of the continental shelf (250 m water depth) to water depths of around 800 m. High resistivities (5β12 Ξ©m) observed above the BSR support the presence of gas hydrate in water depths greater than 600 m. High resistivities (3β4 Ξ©m) at 390β600 m water depth also suggest possible hydrate occurrence within the gas hydrate stability zone (GHSZ) of the continental slope. In addition, high resistivities (4β8 Ξ©m) landward of the GHSZ are coincident with high-amplitude reflectors and low velocities reported in seismic data that indicate the likely presence of free gas. Pore space saturation estimates using a connectivity equation suggest 20β50 per cent hydrate within the lower slope sediments and less than 12 per cent within the upper slope sediments. A free gas zone beneath the GHSZ (10β20 per cent gas saturation) is connected to the high free gas saturated (10β45 per cent) area at the edge of the continental shelf, where most of the seeps are observed. This evidence supports the presence of lateral free gas migration beneath the GHSZ towards the continental shelf
Seismic evidence for shallow gas-escape features associated with a retreating gas hydrate zone offshore west Svalbard
Active gas venting occurs on the uppermost continental slope off west Svalbard, close to and upslope from the present-day intersection of the base of methane hydrate stability (BMHS) with the seabed in about 400 m water depth in the inter-fan region between the Kongsfjorden and Isfjorden cross-shelf troughs. From an integrated analysis of high-resolution, two-dimensional, pre-stack migrated seismic reflection profiles and multibeam bathymetric data, we map out a bottom simulating reflector (BSR) in the inter-fan region and analyze the subsurface gas migration and accumulation. Gas seeps mostly occur in the zone from which the BMHS at the seabed has retreated over the recent past (1975β2008) as a consequence of a bottom water temperature rise of 1Β°C. The overall margin-parallel alignment of the gas seeps is not related to fault-controlled gas migration, as seismic evidence of faults is absent. There is no evidence for a BSR close to the gas flare region in the upper slope but numerous gas pockets exist directly below the predicted BMHS. While the contour following trend of the gas seeps could be a consequence of retreat of the landward limit of the BMHS and gas hydrate dissociation, the scattered distribution of seeps within the probable hydrate dissociation corridor and the occurrence of a cluster of seeps outside the predicted BMHS limit and near the shelf break indicate the role of lithological heterogeneity in focusing gas migration
Virginia-Highland Historic District
Prepared by the spring 2009 Preservation Planning class. The design guidelines were developed to promote preservation and rehabilitation of historic buildings and new construction. Presented within are recommendations for appropriate building materials and design. The guidelines are mean to serve as a tool to property owners and commission members during the design review process.https://scholarworks.gsu.edu/history_heritagepreservation/1042/thumbnail.jp
Estimates of future warming-induced methane emissions from hydrate offshore west Svalbard for a range of climate models
Methane hydrate close to the hydrate stability limit in seafloor sediment could represent an important source of methane to the oceans and atmosphere as the oceans warm. We investigate the extent to which patterns of past and future ocean-temperature fluctuations influence hydrate stability in a region offshore West Svalbard where active gas venting has been observed. We model the transient behavior of the gas hydrate stability zone at 400β500 m water depth (mwd) in response to past temperature changes inferred from historical measurements and proxy data and we model future changes predicted by seven climate models and two climate-forcing scenarios (Representative Concentration Pathways RCPs 2.6 and 8.5). We show that over the past 2000 year, a combination of annual and decadal temperature fluctuations could have triggered multiple hydrate-sourced methane emissions from seabed shallower than 400 mwd during episodes when the multidecadal average temperature was similar to that over the last century (βΌ2.6Β°C). These temperature fluctuations can explain current methane emissions at 400 mwd, but decades to centuries of ocean warming are required to generate emissions in water deeper than 420 m. In the venting area, future methane emissions are relatively insensitive to the choice of climate model and RCP scenario until 2050 year, but are more sensitive to the RCP scenario after 2050 year. By 2100 CE, we estimate an ocean uptake of 97β1050 TgC from marine Arctic hydrate-sourced methane emissions, which is 0.06β0.67% of the ocean uptake from anthropogenic CO2 emissions for the period 1750β2011
Single-Family Residential Development in DeKalb County 1945-1970
The Case studies class of spring of 2010 compiled this resource material. This study focused on suburban residential developments in DeKalb County, Georgia between the end of World War II and 1970 in order to better understand the transformation of the area after the Second World War. The resource includes data on national residential trends, architectural and landscape designs, as well as information on metropolitan Atlanta. The resource was created to support the effort to preserve local neighborhoods, buildings, and landmarks by providing the historic context in which they were created.https://scholarworks.gsu.edu/history_heritagepreservation/1038/thumbnail.jp
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