Time-scale construction and periodizing in Big History: From the Eocene-Oligocene boundary to all of the past

2009 ◽  
Author(s):  
Walter Alvarez ◽  
Philippe Claeys ◽  
Alessandro Montanari
Keyword(s):  
Time Scale ◽  
Scale Construction ◽  
The Past ◽  
Big History

Introductory remarks

1977 ◽  
Vol 280 (972) ◽  
pp. 105-105
Keyword(s):  
Climatic Change ◽  
Food Supply ◽  
Time Scale ◽  
Food Production ◽  
Rapid Change ◽  
Climatic Fluctuations ◽  
The Past ◽  
Wide Range ◽  
The Subject ◽  
Different Sources

In the last year or two there has been a remarkable increase in the interest, both popular and scientific, in the subject of climatic change. This stems from a recognition that even a highly technological society is vulnerable to the effects of climatic fluctuations and indeed may become more so, as margins of surplus food production are reduced, and nations become more interdependent for their food supply. In this respect our concern is with quite small changes - a degree (Celsius) or less in temperature and 10 % or so in rainfall. Probably we may discount some of the more alarmist suggestions of an imminent and rapid change towards near glacial conditions as these are based on very sketchy evidence. However, whatever the time-scale of climatic fluctuations with which we are concerned, we may hope to learn a great deal which is relevant to the factors which will control our future climate from the study of its more extreme vagaries in the past. Information relevant to the weather in such extreme periods is coming forward in increasing detail and volume from a wide range of disciplines. The variety of the evidence, its lack of precision as a strict measure of climate, and the number of different sources all make it difficult for an individual to build up a clear picture of past climates. However such a picture is needed, if explanations and interpretation are to be possible. Ideally one would need a synchronous picture of the climate of the whole world at selected epochs in the past. Various international programmes are directed to forming such pictures.

scholarly journals Historia global o las geografías del pasado. Implicaciones de la perspectiva global y geográfica en la escritura de la historia / Global History or the Geographies of the Past: Implications of a Global and Geographical Perspective in the Writing of History

2017 ◽  
pp. 91
Author(s):  
Francisco Javier Navarro Jiménez
Keyword(s):  
Time Scale ◽  
Global Perspective ◽  
Global History ◽  
Field Of Study ◽  
The Past ◽  
Longue Duree ◽  
Longue Durée ◽  
Geographical Perspective ◽  
Ultimate Purpose ◽  
Sobre Todo

ResumenLa historia global es un campo de estudios emergente. En la aproximación al pasado desde esta perspectiva, el giro territorial y la escala de la larga duración son elementos centrales, con lo que ello supone de solapamientos metodológicos y epistemológicos con otras disciplinas, sobre todo con la geografía. Esta perspectiva ofrece abundantes beneficios, pero también se deben considerar los riesgos que supone. A través de ejemplos concretos de obras escritas desde este campo, el artículo discute la vigencia de conceptos como globalización y ecúmene, pero también cuestiones metodológicas como la larga duración y el determinismo geográfico. Se pretende con ello identificar posibilidades, fortalezas y riesgos en la escritura de la historia global.Palabras claveHistoria global, geografía, territorio, larga duración, solapamientos metodológicos.AbstractGlobal history is an emergent field of study today. To apprehend the past from a global perspective, territorial turn and longue durée time scale become pivotal concepts, with the corresponding methodologic and epistemological overlaps with other disciplines, especially geography. Many benefits can be obtained from this perspective, but there are also risks that need to be considered. Through specific examples of works written from this field, this article examines the validity of concepts of globalization and ecumene, and discusses methodologic aspects related to the longue durée and geographic determinism. The ultimate purpose of it is to identify possibilities, strengths and risks in the writing of global history.Key WordsGlobal history, geography, territory, longue durée, methodologic overlaps.

scholarly journals Spectra of Southern Radio Sources

1977 ◽  
Vol 74 ◽  
pp. 85-97 ◽  
Author(s):  
J. G. Bolton
Keyword(s):  
Time Scale ◽  
Galactic Plane ◽  
Complete Sample ◽  
High Frequencies ◽  
The Past ◽  
Average Accuracy ◽  
Sky Survey ◽  
Two Factors ◽  
Optical Identifications ◽  
One Year

Surveys of the sky between declinations +25° and −90° at 2700 MHz (11 cm) have been in progress for the past 10 years. Excluding some regions close to the galactic plane the whole sky south of +25° has been surveyed to a flux density limit of 0.6 Jy at 2700 MHz and within this area surveys to limits of 0.35, 0.25 or 0.1 Jy have been made covering 3.5 sr. Flux densities have been measured at 5000 MHz for all sources stronger than 0.35 Jy at 2700 MHz. The source positions have an average accuracy of 10″ arc in both coordinates and the positions have been examined for optical identifications on Palomar, ESO or SRC sky survey plates, which now cover 95% of the area. The first part of this paper concerns the relationships between the spectral indices α(2700 to 5000 MHz) and the identifications of the 2300 sources with galactic latitudes greater than 10°. It is a statistically significant sample, since the sources stronger than 0.35 Jy cover 3.5 sr. It is also a representative sample, since no selection was made on the basis of spectral index or identification. It cannot however be claimed as a complete sample, for two reasons. A substantial fraction of sources found in radio surveys at high frequencies are variable - variations of up to a factor of three can occur on a time scale of a year - thus the various sections of the survey are complete only for the relevant epoch. Many of their optical counterparts are also variables - variations of up to a factor of 100 can occur on a time scale of one year. It is hoped to make some assessment of the effect of these two factors in the next two years, when second-epoch Parkes surveys will begin and SRC Schmidt plates will overlap the Palomar Sky Survey.

Earth Satellites

1959 ◽  
Vol 63 (583) ◽  
pp. 394-414 ◽  
Author(s):  
W. H. Stephens
Keyword(s):  
Time Scale ◽  
Space Travel ◽  
The Past ◽  
Scientific Exploration ◽  
Engineering Problems ◽  
The Subject ◽  
Selection Of

So much has been written, both of fact and fancy, about satellites and space travel in the past few years that the selection of material suitable for presentation to the members of a learned Society concerned mainly with purely aeronautical matters is a hazardous and difficult task. I propose in this paper to tackle it by restricting the subject severely to a description of the general characteristics of near earth satellites and the scientific exploration made possible by their use as observing platforms. The later sections of the paper have a bearing on the possibilities and engineering problems of space probes and space travel; I leave it to others to speculate on the likely time scale and types of such activities and attempt instead to make sure that the basic factors involved are made reasonably clear. To set the background it is important to review briefly the actual practical achievements up to the present time.

scholarly journals Torque Reversals in Disk Accreting Pulsars

1998 ◽  
Vol 15 (2) ◽  
pp. 250-253
Author(s):  
Jianke Li ◽  
Dayal T. Wickramasinghe
Keyword(s):  
Neutron Star ◽  
Binary System ◽  
Recent Work ◽  
Time Scale ◽  
Accretion Rate ◽  
Future Studies ◽  
X Ray ◽  
The Past ◽  
X Ray Binaries ◽  
Coherent Picture

AbstractX-ray binaries in which the accreting component is a neutron star commonly exhibit significant changes in their spin. In the system Cen X-3, a disk accreting binary system, the pulsar was observed to spin up at a rate ḟ = 8 × 10−13 Hz s−1 when averaged over the past twenty years, but significant fluctuations were observed above this mean. Recent BASTE observations have disclosed that these fluctuations are much larger than previously noted, and appeared to be a system characteristic. The change in the spin state from spin-up to spin-down or vice-versa occurs on a time scale that is much shorter than the instrument can resolve (≤1 d), but appears always to be a similar amplitude, and to occur stochastically. These observations have posed a problem for the conventional torque–mass accretion relation for accreting pulsars, because in this model the spin rate is closely related to the accretion rate, and the latter needs to be finely tuned and to change abruptly to explain the observations. Here we review recent work in this direction and present a coherent picture that explains these observations. We also draw attention to some outstanding problems for future studies.

A major ‘plateau’ in the radiocarbon time-scale at c. 9650 b.p.: the evidence from Star Carr (North Yorkshire)

Antiquity ◽  
1990 ◽  
Vol 64 (245) ◽  
pp. 836-841 ◽  
Author(s):  
Paul Mellars
Keyword(s):  
Iron Age ◽  
Time Scale ◽  
Upper Atmosphere ◽  
Detectable Change ◽  
Radiocarbon Dates ◽  
Fossil Carbon ◽  
The Past ◽  
Calibration Curves ◽  
Carbon Reservoir ◽  
Radiocarbon Calibration

Over the past 10-20 years archaeologists have become familiar with the problems of potential ‘aberrations’ in the radiocarbon time-scale, arising from factors such as the varying rates of production of I4C in the upper atmosphere, or from the delayed cycling of ‘fossil’ carbon in the overall carbon reservoir. In some cases these aberrations can lead to dramatic ‘wiggles’ in the radiocarbon calibration curves, while in other cases (as, for example, during the Iron Age, around 700 BC) they can lead to substantial ‘plateaux’ during which measured radiocarbon dates show no detectable change over periods of several centuries (Pearson & Stuiver 1986; Stuiver & Pearson 1986).

“Big History” Old and New: Presuppositions, Limits, Alternatives

2015 ◽  
Vol 9 (2) ◽  
pp. 306-326 ◽  
Author(s):  
Allan Megill
Keyword(s):  
Nineteenth Century ◽  
Sixteenth Century ◽  
Large Scale ◽  
Innovative Approach ◽  
Human History ◽  
Comparative History ◽  
Historical Knowledge ◽  
The Past ◽  
History Of ◽  
Big History

In recent years David Christian and others have promoted “Big History” as an innovative approach to the study of the past. The present paper juxtaposes to Big History an old Big History, namely, the tradition of “universal history” that flourished in Europe from the mid-sixteenth century until well into the nineteenth century. The claim to universality of works in that tradition depended on the assumed truth of Christianity, a fact that was fully acknowledged by the tradition’s adherents. The claim of the new Big History to universality likewise depends on prior assumptions. Simply stated, in its various manifestations the “new” Big History is rooted either in a continuing theology, or in a form of materialism that is assumed to be determinative of human history, or in a somewhat contradictory amalgam of the two. The present paper suggests that “largest-scale history” as exemplified in the old and new Big Histories is less a contribution to historical knowledge than it is a narrativization of one or another worldview. Distinguishing between largest-scale history and history that is “merely” large-scale, the paper also suggests that a better approach to meeting the desire for large scale in historical writing is through more modest endeavors, such as large-scale comparative history, network and exchange history, thematic history, and history of modernization.

scholarly journals Meteorological controls on glacier mass balance: empirical relations suggested by measurements on glacier de Sarennes, France

1997 ◽  
Vol 43 (143) ◽  
pp. 131-137 ◽  
Author(s):  
C. Vincent ◽  
M. Vallon
Keyword(s):  
Mass Balance ◽  
Time Scale ◽  
Meteorological Data ◽  
Empirical Relation ◽  
Glacier Mass Balance ◽  
Glacier Surface ◽  
Surface Conditions ◽  
The Past ◽  
Empirical Relations

AbstractGlacial mass-balance reconstruction for a long-term time-scale requires knowledge of the relation between climate change and mass-balance fluctuations. A large number of mass-balance reconstructions since the beginning of the century are based on statistical relations between monthly meteorological data and mass balance. The question examined in this paper is: are these relationships reliable enough for long-term time-scale extrapolation? From the glacier de Sarennes long mass-balance observations series, we were surprised to discover large discrepancies between relations resulting from different time periods. The importance of the albedo in relation to ablation and mass balance is highlighted, and it is shown that it is impossible to ignore glacier-surface conditions in establishing the empirical relation between mass-balance fluctuations and climatic variation; to omit this parameter leads to incorrect results for mass-balance reconstruction in the past based on meteorological data.

Use of Rubidium to Date Loess and Paleosols of the Louchan Sequence, Central China

2000 ◽  
Vol 54 (2) ◽  
pp. 198-205 ◽  
Author(s):  
Jun Chen ◽  
Junfeng Ji ◽  
Yang Chen ◽  
Zhisheng An ◽  
John A. Dearing ◽  
...  
Keyword(s):  
Sedimentation Rate ◽  
Time Scale ◽  
Winter Monsoon ◽  
Central China ◽  
Early Pleistocene ◽  
Monsoon Climate ◽  
The Past ◽  
Pleistocene Climate ◽  
Curvilinear Relation ◽  
The Last Glacial

Rb concentrations, analyzed at 20-cm intervals from the Luochuan sequence of loess and paleosols, are sensitive to the loess–paleosol alternation controlled by monsoon climate. Because it is geochemically immobile, Rb can be well preserved in the loess–paleosol sequence after deposition, and its concentration depends mainly on properties of the winter monsoon-blown dust and on intensity of the summer monsoon-induced pedogenesis. A curvilinear relation has been developed between the measured Rb-concentration and the apparent sedimentation rate for the last glacial–interglacial cycle. This relation provides a time scale that corresponds well with the presently accepted ages for paleomagnetic reversals of Brunhes/Matuyama and Jaramillo events. With allowance for reduced Rb concentrations caused by early Pleistocene climate, the Rb-based time scale is also consistent with the boundary ages of other major paleomagnetic reversals of the past 2.58 myr.

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