Abstract In the depths of planet Earth there is a layer composed essentially by molten iron, which moves in a complex and constant manner on a planetary scale (Earth's outer core). This movement is responsible for the generation of the magnetic field that encompasses the planet, which in turn has (today) a predominantly dipolar geometry. Asymmetries in the dynamics of the Earth's outer core, provided by its (magneto)hydrodynamics and the physical heterogeneities of the structures above and below this fluid layer, can be observed on Earth's surface via non-dipolar features in the geomagnetic field. Studying these features is a passport to understand the unreachable interior of our planet, and some multidisciplinary correlations. For this purpose, we need to comprehend the magnetic field at present (e.g., via geomagnetic observatories and satellites), as well as its fossil record in archaeological and geological materials collected on the surface, especially in regions where non-dipolar behaviour are significantly expressed. Currently, an outstanding feature that displays a major non-dipolar contribution is mostly located over the southern portion of South America, where the intensity manifests remarkably low values – called South Atlantic Anomaly. In this context, the region of the Jequitinhonha and Mucuri river valleys (Southeast Brazil) emerges as an excellent natural laboratory since it is located within this outstanding non-dipolar feature of the modern geomagnetic field. In this article, I present a brief review of the Earth's magnetic field for the past four centuries and discuss some of its main features from the perspective of the valleys region. At the end, I emphasize the advantage of the valleys region in the study of the Earth's magnetic field in geographical, archaeological, and geological terms.

中文翻译：

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从Jequitinhonha 和Mucuri 河谷看过去几个世纪的地球磁场：巴西南大西洋异常的自然观测站

摘要 在地球深处有一层主要由铁水组成的层，铁水在行星尺度（地球的外核）上以复杂和恒定的方式运动。这种运动导致了环绕行星的磁场的产生，而行星又（今天）具有主要的偶极几何形状。通过地磁场中的非偶极特征，可以在地球表面观察到由（磁）流体动力学和该流体层上方和下方结构的物理异质性提供的地球外核动力学的不对称性。研究这些特征是了解我们星球无法到达的内部以及一些多学科相关性的通行证。为此，我们需要了解当前的磁场（例如，通过地磁观测站和卫星），以及在地表收集的考古和地质材料中的化石记录，特别是在非偶极行为显着表现的地区。目前，一个显示主要非偶极贡献的突出特征主要位于南美洲南部，在那里强度表现出非常低的值——称为南大西洋异常。在这种情况下，Jequitinhonha 和穆库里河谷地区（巴西东南部）由于位于现代地磁场的这一突出的非偶极特征内，因此成为了一个极好的自然实验室。在这篇文章中，我简要回顾了地球' 过去四个世纪以来的磁场，并从山谷地区的角度讨论了它的一些主要特征。最后，我强调了山谷地区在地理、考古和地质方面的地球磁场研究中的优势。