Main Article Content
Ten fireplaces from Mannheim-Wallstadt (MW) and four ovens from Herrenchiemsee (HC) were studied with regard to their archaeomagnetic properties. The ages of the medieval structures were only poorly known and an age dating was intended with the help of the standard curves for the declination and inclination of the geomagnetic field of the past 2000 years, as set up by Thellier (1981) for France. The stability of the NRM was tested with Thellier's test. Of the ten MW fireplaces, only one passed the test, whereas of the four ovens of HC, all passed the test but one of them had to be excluded because of secondary displacements within the structure. The MW fireplace could be dated to 670-700 A.D., in agreement with other archaeological age determinations for the fireplaces. The ovens from HC yielded an age between 1100 and 1170 A.D. The ovens showed the effect of magnetic refraction. Model calculations carried out on circular ring structures require a susceptibility of the oven material of the order of 0.5 SI units to explain the observed effect. The presently observed mean susceptibility at room temperature is only around 5 x 10-3 SI units. However, heating of the material at 550° C for 2 h in a reducing environment was able to increase the susceptibility by a factor of 20. This effect is explained by the reduction of secondary iron oxides and hydroxides to magnetite. Another increase by a factor of about 1.5 is obtained from the Hopkinson effect (increase of susceptibility with temperature) at the blocking temperature of magnetite. Combining all effects, it is possible to attain values for the susceptibility at the blocking temperature of magnetite as high as 0.2 SI units, which is the order of magnitude required for the explanation of the observed effect of magnetic refraction. This effect demands that special considerations be made during archaeomagnetic sampling from archaeological ovens or kilns.
Authors who publish with this journal as of Vol. 63 agree to the following terms:
a. Authors share the copyright with this journal in equal parts (50% to the journal, 50% to the lead author), and grant the journal right of first publication, with the work after publication simultaneously licensed under Creative Commons Attribution License CC BY-NC-ND 4.0 that allows others to share the work with an acknowledgment of the work's authorship and initial publication in this journal.
b. Authors may enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgment of its initial publication in this journal, and a reference to this copyright notice.
c. Authors are permitted and encouraged to post their work online (e.g., in institutional repositories or on their website) during the submission process, as this can lead to productive exchanges and earlier and greater citation of published work and better sales of the copyright.
Authors retain copyright and grant the Journal of Geophysics right of first publication, with the work three years after publication simultaneously licensed under the Creative Commons BY-NC-ND 4.0 License that allows others to share the work (with an acknowledgment of the work's authorship and initial publication in this journal), except for commercial purposes and for creating derivatives.
Authors can enter into separate, additional, but non-commercial contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository, but not publish it in a book), with an acknowledgment of its initial publication in this journal.
Authors are permitted and encouraged to post their work online (e.g., in institutional repositories or on their website) before and during the submission process, as that can lead to productive exchanges, as well as earlier and greater citation of published work (See The Effect of Open Access).
This journal is one of a handful of scholarly journals that publish original scientific works under CC BY-NC-ND 4.0 - the only Creative Commons license affording the authors' intellectual property absolute worldwide protection.
Journal of Geophysics is published under the scholar-publishers model, meaning authors do not surrender their copyright to us. Instead, and unlike corporate publishers like Elsevier or Springer Nature that resell copyright to third-parties for up to $80,000 (per paper, per transaction!), the Journal of Geophysics authors share copyright equally with this journal.
Therefore, all the proceeds from reselling copyright to third parties get shared to equal parts (50% to the journal, 50% to the lead author). Under the Berne Convention, this protection is an inheritable right that lasts for as long as the rightsholder lives + 50 years.
By submitting to this journal, the lead author, on behalf of all co-authors, grants permission to this journal to represent all co-authors in negotiating copyright sales and collecting proceeds. The lead author should negotiate with his/her co-authors the modalities of distributing the lead author's portion of the proceeds. Usually, this is per pre-agreed percentage of each co-author's contribution to creating the copyrighted work. (more...)
Aitken, M.J., Hawley, H.N. (1971) Archaeomagnetism: Evidence for magnetic refraction in kiln structures. Archaeometry 13:83-85
Bergmann, L., Schaefer, C. (1974) Lehrbuch der Experimentalphysik II, W. de Gruyter, Berlin
Graham, I.D.G., Scollar, I. (1976) Limitation on magnetic prospection in archaeology imposed by soil properties. Archaeo-Physica 6:1-126
Harold, M.R. (1960) Magnetic dating: kiln wall fall-out. Archaeometry 3:47-49
Jackson, I.D. (1975) Classical electrodynamics. J. Wiley and Sons, London
Landolt-Bornstein (1970) Zahlenwerte und Funktionen aus Naturwissenschaften und Technik, Vol. III, 4b
Le Borgne, E. (1955) Susceptibilite magnetique anormale du sol superficiel. Ann. Geophys. 11:399-419
Le Borgne, E. (1960a) Influence du feu sur Jes proprietes magnetiques de sol et sur celles du schiste et du granite. Ann. Geophys. 16:159-196
Le Borgne, E. (1960b) Etude experimentale du trainage magnetique dans le cas d'un ensemble du grains magnetiques tres fins disperses dans une substance non magnetique. Ann. Geophys. 16:445-503
Le Borgne, E. (1965) Les proprietes magnetiques du sol. Application a la prospection des sites archeologiques. Archaeo-Physica I, Beihefte der Bonner Jahrbucher 15:1-20
Mullins, C.E. (1974) The magnetic properties of soil and their application to archaeological prospection. Archaeo-Physica 5:143-348
Rumble, D. (Ed.) (1976) Reviews in Mineralogy, Vol. 3: Oxide Minerals. Min. Soc. of America, Short Course Notes, Southern Printing Comp., Blacksburg, Virginia, USA
Schurr, K. (1983) Archaomagnetische Untersuchungen an Feuerstellen aus Mannheim-Wallstadt und Oren aus Herrenchiemsee. Unpubl. Thesis, University of Munich
Thellier, E., Thellier, O. (1959) Sur l'intensite du champ magnetique terrestre dans le passe historique et geologique. Ann. Geophys. 15:285-376
Thellier, E. (1981) Sur la direction du champ magnetique terrestre, en France, durant les deux derniers millenaires. Phys. Earth Planet. Inter. 24:89-132
Weaver, G.H. (1962) Archaeomagnetic measurements on the Second Boston Experimental Kiln. Archaeometry 5:93-104