Thousands of years ago, Earth\u2019s magnetic field underwent a significant power surge over a part of the planet that included the ancient kingdom of Mesopotamia. People at the time probably never even noticed the fluctuation, but signs of the anomaly, including previously unknown details, were preserved in the mud bricks that they baked, new research has found. <\/p>\n
When scientists recently examined bricks dating from the third to the first millennia BC in Mesopotamia \u2014 which encompassed present-day Iraq and parts of what is now Syria, Iran and Turkey \u2014 they detected magnetic signatures in those from the first millennium, indicating that the bricks were fired at a time when Earth\u2019s magnetic field was unusually strong. Stamps on the bricks naming Mesopotamian kings enabled researchers to confirm the time range for the magnetic spike. <\/p>\n
Their findings corresponded with a known magnetic surge called the \u201cLevantine Iron Age geomagnetic Anomaly,\u201d which took place between 1050 and 550 BC. It had previously been documented in artifacts from the Azores, Bulgaria and China using archaeomagnetic analysis \u2014 examining grains in pottery and ceramic archaeological objects for clues about Earth\u2019s magnetic activity, scientists reported December 18 in the journal Proceedings of the National Academy of Sciences. <\/p>\n
\u201cIt is really exciting that ancient artifacts from Mesopotamia help to explain and record key events in Earth history such as fluctuations in the magnetic field,\u201d said study coauthor Mark Altaweel, a professor of Near East archaeology and archaeological data science at the University College London\u2019s Institute of Archaeology. <\/p>\n
When an ancient artifact contains organic matter, such as bone or wood, scientists can learn how old it is through radiocarbon dating, which compares ratios of decay preserved in carbon isotopes. But for inorganic artifacts \u2014 pottery or ceramic objects \u2014 archaeomagnetic analysis is necessary to reveal their age, said lead study author Matthew Howland, an assistant professor in the department of anthropology at Wichita State University in Kansas. <\/p>\n
\u201cArchaeomagnetic dating can be applied to any kind of magnetically sensitive materials that have been heated up,\u201d Howland said. And its usefulness extends beyond archaeology. <\/p>\n
\u201cGeologists often use analysis of rocks to study Earth\u2019s magnetic fields, but in more recent times when there\u2019s not the possibility of studying very recent rocks because they haven\u2019t had the time to form yet, we need to use archaeological artifacts,\u201d he said. \u201cWe can think of mud bricks or pottery as human-made rocks to study Earth\u2019s magnetic fields.\u201d <\/p>\n
Before this new study, there was little precise archaeomagnetic evidence from Mesopotamian artifacts dating to this time. <\/p>\n
\u201cThe lack of data there really restricted our ability to understand the conditions of Earth\u2019s magnetic field in that region,\u201d Howland said. It also meant that archaeologists couldn\u2019t accurately calculate the ages of many sites in Mesopotamia, \u201can incredibly important region in world archaeology.\u201d <\/p>\n
Earth is surrounded by a magnetosphere \u2014 an invisible bubble of magnetism generated by the powerful churning of molten metals at Earth\u2019s core. It prevents our atmosphere from being stripped away by solar winds blasting it from the sun. While the magnetosphere has been a constant presence for billions of years, its strength waxes and wanes over time. (Human health is not directly affected by magnetic field fluctuations, according to the US Geological Survey.) <\/p>\n
Clay artifacts that were baked at high temperatures retain a \u201cfingerprint\u201d of Earth\u2019s magnetism at the time in minerals such as iron oxide affected by magnetism. Retrieving that fingerprint involves a series of magnetic experiments that repeatedly heat and cool the object, exposing it to magnetic fields and then removing them. This process creates a series of new fingerprints, which are compared with the object\u2019s original magnetic intensity. <\/p>\n
Scientists can then match the object to a specific period of activity in Earth\u2019s magnetic field. <\/p>\n
\u201cOverall, this is exciting work because it is helping us understand what Earth\u2019s magnetic field is doing through time and will also help determine the age of artifacts that otherwise would be impossible,\u201d said Cau\u00ea S. Borlina, a postdoctoral fellow in the department of Earth and planetary sciences at Johns Hopkins University. Borlina, who was not involved in the study, conducts research on ancient and modern magnetic fields, and their impact on planet formation and habitability. <\/strong> <\/p>\n The new analysis not only filled an important data gap\u2014it also revealed new clues about that period\u2019s magnetic anomaly. <\/p>\n Of the 32 stones that the researchers sampled, five bore stamps linking them to the reign of Nebuchadnezzar II, between 604 and 562 BC. Measurements of magnetism in the stones showed that the magnetic field strengthened quickly and intensely when the bricks were made. The stamps on the bricks therefore created a snapshot of a magnetic power surge that spanned just a few decades. <\/p>\n \u201cThe next steps are to continue this work, apply it to more mud bricks from Mesopotamia and further improve the curve that we can produce of the intensity of Earth\u2019s magnetic field over time,\u201d Howland said. <\/p>\n \u201cBut perhaps even more exciting is that archaeologists working at sites in Iraq and Syria can look at our data and apply the same techniques to undated artifacts,\u201d he added. \u201cThis can help resolve a lot of the chronological debates that occur in the region, about the chronology of kings.\u201d <\/p>\n Mindy Weisberger is a science writer and media producer whose work has appeared in Live Science, Scientific American and How It Works magazine.<\/em><\/em> <\/p>\n\n Thousands of years ago, Earth\u2019s magnetic field underwent a significant power surge over a part of the planet that included the ancient kingdom of Mesopotamia. People at the time probably never even noticed the fluctuation, but signs of the anomaly, including previously unknown details, were preserved in the mud bricks that they baked, new research <\/p>\n","protected":false},"author":0,"featured_media":13349,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[23],"tags":[],"class_list":{"0":"post-13348","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-world"},"_links":{"self":[{"href":"https:\/\/shareperformanceinsight.com\/index.php\/wp-json\/wp\/v2\/posts\/13348","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/shareperformanceinsight.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/shareperformanceinsight.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"replies":[{"embeddable":true,"href":"https:\/\/shareperformanceinsight.com\/index.php\/wp-json\/wp\/v2\/comments?post=13348"}],"version-history":[{"count":0,"href":"https:\/\/shareperformanceinsight.com\/index.php\/wp-json\/wp\/v2\/posts\/13348\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/shareperformanceinsight.com\/index.php\/wp-json\/wp\/v2\/media\/13349"}],"wp:attachment":[{"href":"https:\/\/shareperformanceinsight.com\/index.php\/wp-json\/wp\/v2\/media?parent=13348"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/shareperformanceinsight.com\/index.php\/wp-json\/wp\/v2\/categories?post=13348"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/shareperformanceinsight.com\/index.php\/wp-json\/wp\/v2\/tags?post=13348"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}