The strength of the Earth’s magnetic field from Pre-Pottery to Pottery Neolithic, Jordan

2021 ◽  
Author(s):  
Anita Di Chiara ◽  
Lisa Tauxe ◽  
Thomas Levy ◽  
Mohammand Najjar ◽  
Fabio Florindo ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Dipole Moments ◽  
Ancient Egypt ◽  
Archaeological Sites ◽  
Southern Levant ◽  
Short Term ◽  
The Past ◽  
The Earth ◽  
Secular Variations ◽  
Geological Formations

<p>Constraining the secular variations of the Earth’s magnetic field strength in the past is fundamental to understanding short term processes of the geodynamo. Such records constitute a powerful and independent dating tool for archaeological sites and geological formations. In this study, we present 10 new and robust archaeointensity results from Pre-Pottery to Pottery Neolithic and, for one of the first times, flint (burnt chert) from Jordan. Two of these results constitute the oldest archaeointensity data for the entire Levant, ancient Egypt and Mesopotamia extending the archaeomagnetic dating reference for the Holocene. Virtual Axial Dipole Moments (VADM)s show that the Earth’s magnetic field in the Southern Levant was weak (about half the present field) at around 7,600 years BCE, recovering its strength to greater than the present field around 7,100 BCE and gradually weakening again around 5,200 years BCE. In addition, successful results obtained from burnt flint demonstrate the potential of this rarely used material in archaeomagnetic research, in particular for prehistoric periods from the first use of fire to the invention of pottery.</p>

scholarly journals The strength of the Earth’s magnetic field from Pre-Pottery to Pottery Neolithic, Jordan

2021 ◽  
Vol 118 (34) ◽  
pp. e2100995118
Author(s):  
Anita Di Chiara ◽  
Lisa Tauxe ◽  
Thomas E. Levy ◽  
Mohammad Najjar ◽  
Fabio Florindo ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Dipole Moments ◽  
Ancient Egypt ◽  
Archaeological Sites ◽  
Reference Curve ◽  
Earth’S Magnetic Field ◽  
Short Term ◽  
The Past ◽  
Earth's Magnetic Field ◽  
Geological Formations

Constraining secular variation of the Earth’s magnetic field strength in the past is fundamental to understanding short-term processes of the geodynamo. Such records also constitute a powerful and independent dating tool for archaeological sites and geological formations. In this study, we present 11 robust archaeointensity results from Pre-Pottery to Pottery Neolithic Jordan that are based on both clay and flint (chert) artifacts. Two of these results constitute the oldest archaeointensity data for the entire Levant, ancient Egypt, Turkey, and Mesopotamia, extending the archaeomagnetic reference curve for the Holocene. Virtual Axial Dipole Moments (VADMs) show that the Earth’s magnetic field in the Southern Levant was weak (about two-thirds the present field) at around 7600 BCE, recovering its strength to greater than the present field around 7000 BCE, and gradually weakening again around 5200 BCE. In addition, successful results obtained from burnt flint demonstrate the potential of this very common, and yet rarely used, material in archaeomagnetic research, in particular for prehistoric periods from the first use of fire to the invention of pottery.

Some archaeomagnetic results from Greece

1963 ◽  
Vol 58 ◽  
pp. 8-13 ◽  
Author(s):  
J. C. Belshé ◽  
K. Cook ◽  
R. M. Cook
Keyword(s):  
Magnetic Field ◽  
The Other ◽  
Secular Change ◽  
Magnetic Oxides ◽  
Archaeological Remains ◽  
Main Field ◽  
Thermoremanent Magnetization ◽  
The Past ◽  
The Earth ◽  
The Magnetic Field

Many clays and stones contain particles of magnetic oxides of iron. These particles, if heated above their Curie points, which range up to 670° C., lose whatever magnetism they have; and when they cool back through their Curie points, they acquire a new ‘thermoremanent’ magnetization under the influence of the surrounding magnetic field, which generally is the magnetic field of the earth. That field is changing continuously, both in direction and intensity, and the course of its secular change is not yet understood; the change is compound, one factor being the main field, which may be fairly stationary over long periods, and the other being the numerous minor regional fields, which move and alter relatively quickly and largely determine the local variations in the magnetic field. So it is dangerous to extrapolate values for local variations either for more than a century or two in time or for more than five to ten degrees in space. At present the best hope for discovering past changes in the earth's field is from the thermoremanent magnetization of burnt clays and stones, where the date of the burning is reasonably closely fixed from other evidence. Such knowledge is obviously of interest to geophysicists, but for periods and places where the past course of the earth's field has been ascertained, archaeomagnetism—that is the study of the thermoremanent magnetization of archaeological remains—can help archaeologists too. It should be evident on reflection that if an archaeomagnetic specimen is to be useful certain requirements are necessary. First, the locality where it was magnetized must be known. Secondly, for the study of direction, the sample's orientation at the time when it was magnetized must be recorded, so that the inclination [or dip] and declination [or compass bearing] of its own thermoremanent magnetism can be related to the horizontal and to true North respectively.

The Accuracy of Radiocarbon Dates

Antiquity ◽  
1963 ◽  
Vol 37 (147) ◽  
pp. 213-219 ◽  
Author(s):  
W. F. Libby
Keyword(s):  
Magnetic Field ◽  
Solar System ◽  
Cosmic Ray ◽  
Average Life ◽  
Radiocarbon Dates ◽  
Cosmic Ray Intensity ◽  
Rapid Mixing ◽  
The Past ◽  
The Earth ◽  
The Magnetic Field

The first test of the accuracy of dates obtained by the radiocarbon technique was made by determining whether dates so obtained agreed with the historical dates for materials of known age (n. 1). The validity of the radiocarbon method continues to be an important question, especially in the light of the numerous results that have been accumulated and the greater precision of the technique during the past few years (n. 2).The radiocarbon content of the biosphere depends on three supposedly independent geophysical quantities: (i) the average cosmic ray intensity over a period of 8000 years (the average life of radiocarbon) as measured in our solar system but outside the earth's magnetic field (n. 1); (ii) the magnitude (but not the orientation, because of the relatively rapid mixing over the earth's surface) of the magnetic field in the vicinity of the earth, averaged over the same period (n. 1,3); and (iii) the degree of mixing of the oceans during the same period (n. 1). The question of the accuracy of radiocarbon dates therefore is of interest to geophysicists in general as well as to the archaeologists, geologists and historians who use the dates.Previous workers in this area (n. 1, 2) have reported some discrepancies, and it is the purpose here to consider the matter further.

scholarly journals II. On the Classification of the Cretaceous Beds

1865 ◽  
Vol 2 (11) ◽  
pp. 197-199 ◽  
Author(s):  
Robert A. C. Godwin-Austen
Keyword(s):  
The Past ◽  
The Earth ◽  
History Of ◽  
The Subject ◽  
Geological Formations ◽  
Geological Magazine

The two Memoirs by Dr. Reynès, on the Cretaceous formation, which were noticed in the ninth number of the Geological Magazine, suggest two questions: how far subdivisions there proposed are applicable to the Cretaceous series of this country; and, next, as to the sufficiency of the ground on which the synchronism of the subdivisions of geological formations has been based. The subject of the second Memoir, ‘De l'Étage,’ involves considerations which might be well extended to the whole range of the geological series: indeed, it will hardly be profitable to make much progress with the past physical history of the earth until rules for determining geological horizons shall be established.

On possible origins of relatively short-term variations in the solar structure

1990 ◽  
Vol 330 (1615) ◽  
pp. 627-640 ◽  
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Large Scale ◽  
Convection Zone ◽  
Thermal Structure ◽  
Latitudinal Distribution ◽  
Short Term ◽  
The Earth ◽  
Total Luminosity ◽  
Open Question

The general large-scale redistribution of magnetic field over the solar cycle is possibly associated with an overall variation of thermal structure of the convection zone, which modulates not only the total luminosity but also the latitudinal distribution of radiative flux, thereby modifying the irradiance of the Earth. Whether the cause of this variation lies within the convection zone or is more deeply seated is still an open question.

scholarly journals Polygon “Simeiz-Katsively” - changes in the average pole of the Earth and the geomagnetic field over the last century

2019 ◽  
Vol 30 ◽  
pp. 15004
Author(s):  
Larisa Volvach ◽  
Galina Kurbasova ◽  
Andrej Dmytrotsa ◽  
Dmitry Neyachenko
Keyword(s):  
Geomagnetic Field ◽  
Past Century ◽  
Geodetic Coordinates ◽  
The Past ◽  
The North ◽  
The Earth ◽  
Secular Variations ◽  
North Latitude

The character of changing the trajectory of the middle of the North geographical pole of the Earth's surface over the last century is studied. The peculiarities in the changes of its coordinates are established. The epochs of the appearance of especial points are compared with the epochs of jumps in the data on the parameters of the geomagnetic field. A model of secular variations of geomagnetic declination at a point with geodetic coordinates of 90° north latitude, 0° west longitude is obtained. Coherent relationships have been established between changes in the parameters of the Earth’s middle pole and the geomagnetic field over the past century.

Archaeomagnetic directions and intensities from New Zealand: evidence for a fifteenth century AD archaeomagnetic “spike” in the SW Pacific?

2020 ◽  
Author(s):  
Gillian M. Turner ◽  
Rimpy Kinger ◽  
Bruce McFadgen ◽  
Monique Gevers
Keyword(s):  
New Zealand ◽  
Fifteenth Century ◽  
Dipole Moments ◽  
Archaeological Sites ◽  
The Past ◽  
Sw Pacific ◽  
Earth Ovens ◽  
Reference Curves ◽  
North And South ◽  
Calendar Dates

<p>The arrival of the great Maori waka and the settlement of New Zealand some seven or eight hundred years ago are described in oral history, but details of exactly when and how colonisation occurred are undocumented. Radiocarbon dating of early archaeological sites is particularly problematic, due to the inbuilt age of datable materials, and non-linearity and ambiguity in the calibration of measurements to calendar dates. Hangi stones, used as heat retainers in traditional Maori earth ovens, hold thermoremanent records of Earth’s magnetic field at the time of their last cooling. Matching the directions of these magnetizations to established reference curves provides alternative, archaeomagnetic, estimates of age. Our results cover the past 700 years, with a cluster of dates between 1500 and 1600 AD, from both North and South Islands, but none earlier than 1300 AD, thus supporting a model of rapid coordinated migration around that time. Archaeointensity data have been obtained from sixteen distinct archaeological features, including twelve hangi from eight sites, and from them the first archaeointensity record for New Zealand has been constructed. To this has been added other archaeointensity and palaeointensity data from the SW Pacific region and virtual axial dipole moments (VADMs) have been plotted. This plot outlines steady VADM values of about 8 x10<sup>22</sup> Am<sup>2</sup> from 1000-1300 AD, and 9.5 x10<sup>22</sup> Am<sup>2</sup> from 1500 AD to the present, with an intervening sharp peak in the early 15<sup>th</sup> century when the VADM reached about 13 x10<sup>22</sup> Am<sup>2</sup>. This peak bears many similarities to archaeomagnetic “jerks” and “spikes” in northern hemisphere records from the first millennia BC and AD. However, it is the first such feature to be found in the southern hemisphere at this date, suggesting, in accordance with recent modelling, that it may be a feature of the non-dipole field, associated with rapid growth and decay of an intense flux patch on the core-mantle boundary.</p>

The Origin of the Moon and its Relationship to the Origin of the Solar System

1962 ◽  
Vol 14 ◽  
pp. 133-148 ◽  
Author(s):  
Harold C. Urey
Keyword(s):  
Solar System ◽  
The Moon ◽  
The Past ◽  
The Earth ◽  
Short Period ◽  
Origin Of The Moon

During the last 10 years, the writer has presented evidence indicating that the Moon was captured by the Earth and that the large collisions with its surface occurred within a surprisingly short period of time. These observations have been a continuous preoccupation during the past years and some explanation that seemed physically possible and reasonably probable has been sought.

On the Configuration of the Magnetic Field of β CrB

1976 ◽  
Vol 32 ◽  
pp. 613-622
Author(s):  
I.A. Aslanov ◽  
Yu.S. Rustamov
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Radial Velocity ◽  
Magnetic Field Strength ◽  
Complex Shape ◽  
Rotation Period ◽  
Field Variation ◽  
Magnetic Field Variation ◽  
Secular Variations ◽  
The Magnetic Field

SummaryMeasurements of the radial velocities and magnetic field strength of β CrB were carried out. It is shown that there is a variability with the rotation period different for various elements. The curve of the magnetic field variation measured from lines of 5 different elements: FeI, CrI, CrII, TiII, ScII and CaI has a complex shape specific for each element. This may be due to the presence of magnetic spots on the stellar surface. A comparison with the radial velocity curves suggests the presence of a least 4 spots of Ti and Cr coinciding with magnetic spots. A change of the magnetic field with optical depth is shown. The curve of the Heffvariation with the rotation period is given. A possibility of secular variations of the magnetic field is shown.

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