1,734,392 research outputs found
High-resolution cyclostratigraphy data from ODP Site 207-1258
No full textHere we present a high-resolution cyclostratigraphy based on X-ray fluorescence (XRF) core scanning data from a new record retrieved from the tropical western Atlantic (Demerara Rise, ODP Leg 207, Site 1258). The Eocene sediments from ODP Site 1258 cover magnetochrons C20 to C24 and show well developed cycles. This record includes the missing interval for reevaluating the early Eocene part of the Geomagnetic Polarity Time Scale (GPTS), also providing key aspects for reconstructing highresolution climate variability during the Early Eocene Climatic Optimum (EECO). Detailed spectral analysis demonstrates that early Eocene sedimentary cycles are characterized by precession frequencies modulated by short (100 kyr) and long (405 kyr) eccentricity with a generally minor obliquity component. Counting of both the precession and eccentricity cycles results in revised estimates for the duration of magnetochrons C21r through C24n. Our cyclostratigraphic framework also corroborates that the geochronology of the Eocene Green River Formation (Wyoming, USA) is still questionable mainly due to the uncertain correlation of the "Sixth Tuff" to the GPTS. Right at the onset of the long-term Cenozoic cooling trend the dominant eccentricitymodulated precession cycles of ODP Site 1258 are interrupted by strong obliquity cycles for a period of ~800 kyr in the middle of magnetochron C22r. These distinct obliquity cycles at this low latitude site point to (1) a high-latitude driving mechanism on global climate variability from 50.1 to 49.4 Ma, and (2) seem to coincide with a significant drop in atmospheric CO2 concentration below a critical threshold between 2- and 3-times the pre-industrial level (PAL). The here newly identified orbital configuration of low eccentricity in combination with high obliquity amplitudes during this ~800-kyr period and the crossing of a critical pCO2 threshold may have led to the formation of the first ephemeral ice sheet on Antarctica as early as ~50Ma ago
Baronial reform and revolution in England, 1258-1267
No full textThe years between 1258 and 67 comprise one of the most influential periods in the Middle Ages in England. This turbulent decade witnessed a bitter power struggle between King Henry III and his barons over who should control the government of the realm. Before England eventually descended into civil war, a significant proportion of the baronage had attempted to transform its governance by imposing on the crown a programme of legislative and administrative reform far more radical and wide-ranging than Magna Carta in 1215. Constituting a critical stage in the development of parliament, the reformist movement would remain unsurpassed in its radicalism until the upheavals of the seventeenth century. Simon de Montfort, the baronial champion, became the first leader of a political movement to seize power and govern in the king's name.
The essays collected here offer the most recent research into and ideas on this pivotal period. Several contributions focus upon the roles played in the political struggle by particular sections of thirteenth-century society, including the Midland knights and their political allegiances, aristocratic women, and the merchant elite in London. The events themselves constitute the second major theme of this volume, with subjects such as the secret revolution of 1258, Henry III's recovery of power in 1261, and the little studied maritime theatre during the civil wars of 1263-7 being considered
Eocene sedimentary calcium carbonate contents from ODP Sites 207-1258
No full textHigh resolution Eocene records of CaCO3 concentrations were calculated, by regression, using sediment physical property data and measurements of sediment CaCO3 content. We developed an astronomically calibrated age model for Site 1258 (Demerara rise). Detailed chronologies for sites 1267 and 1210 were generated by tuning clear, correlatable events in their respective CaCO3 (%) records to the astronomically calibrated CaCO3 (%) record from Site 1258
Santa Fe (ATSF) 1258
No full textA photograph print showing Santa Fe (ATSF) 1258, 4-6-2 (BLW), class 1226, on passenger train, Los Angeles, CA
Modificación RM 1258/95
No full textModificar la RM 1258/95 en su Anexo II, requisitos de ingreso del título de Ingeniero en Seguridad e Higiene en el Trabaj
(Table T2) Relative signal intensity of intact polar lipids in sediments from ODP Sites 207-1257 and 207-1258
No full textWe report results from the analysis of intact polar lipids (IPLs) in sediments from Ocean Drilling Program Sites 1257 and 1258. IPLs, constituting the cell membranes of living organisms, were detected in organic-lean sediments but not in underlying organic-rich black shales. Microbial activity in organic-lean sediments is likely due to sulfate-dependent oxidation of methane whereas difficulties detecting IPLs in black shales are interpreted to result from unfavorable signal-to-noise ratios due to low cell concentrations in combination with extremely high analytical noise created by uncharacterized organic matrix. IPLs found are consistent with a low-diversity community of archaea and bacteria. The concentrations of IPLs are more than one order of magnitude lower than those in Neogene deep subsurface sediments at the Peruvian margin, suggestive of significantly lower cell concentrations in Demerara Rise. This finding is consistent with inferred low rates of subsurface microbial activity
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