More Geomagnetic News (Albeit 565,000,000 Years Old)

Two days ago, Ferrebeekeeper wrote about Earth’s magnetic field, an underappreciated invisible force-field which keeps the planet habitable by preventing solar wind from blowing away our atmosphere and oceans (we need those!).  Long ago, Venus and Mars seemingly had liquid oceans and nice atmospheres, but something went wrong (?) with their magnetic fields a billion or so years ago, and just look at them now (tuts censoriously). But maybe we shouldn’t be so quick to judge our neighbors…Five hundred and sixty-five million years ago, the Earth underwent a magnetic crisis too.

Geologists have been studying fragments of  plagioclase and clinopyroxene from the ancient continental shield of Canada to learn about the state of the planet’s magnetic fields in the ancient past.  As they form, these crystals trap tiny magnetized iron fragments in place like the needles of little compasses.  Scientists can thus study the deep history of the magnetosphere.  As they studied magnetic crystals that were formed 565 million years ago, they found some troubling things: half a billion years ago, the Earth’s magnetic field was over 10 times weaker than what it is today.  Additionally the poles were rapidly fluctuating between north and south at an unexpected rate.

A closer reading of all of this suggests that 550 million years ago the Earth’s magnetic field nearly collapsed! (for a look at what that means, just walk around Mars).  Life was saved because the solid nickel iron core of Earth nucleated from the molten core at that time.  Instead of a field collapse, our magnetic field became much stronger as the spinning solid inner core and the convection cycles of the molten outer core worked together to form a super geodynamo.  Coincidentally, 541 million years ago is familiar to paleontologists as the inception of the Cambrian explosion, when multitudinous animal life forms appeared on Earth. It is such an important point that it divides the Phanerozoic (filled with mushrooms, megafauna, liverworts, and Roman centurions) from the Proterozoic (billions of years of bacterial soup).   Just a coincidence?

 

The Votive Crown of Oswald at Hildesheim

Gosh, we have looked at a lot of crowns, haven’t we?  You would think that, after all of these posts, we would have started to run out of royal headwear, but we haven’t even remotely begun to get to the back of history’s vast royal treasury.  Nothing seems to interest humans quite so much as status, and nothing says status like a gold hat which proclaims “I am better than than those around me”.  Today’s crown however is not meant for a human head: it is a votive crown which is devoted to the idea that there are  aspects of status which fundamentally transcend even our sad status-driven lives.  This idea is maybe at the heart of religion–which is an even more naked manifestation of the human need for hierarchical status and tribal belonging than politics and kingship (although they are all knit together in a disturbing way).

Enough philosophizing…above is the crown of of Saint Oswald made of gold, silver, pearls, shell, and gemstones.  It seems to date from the late 12th century AD but may be of earlier construction.  Elements of the crown, such as the Roman cameo and the intaglios are definitely ancient pieces which have been repurposed into the saint’s crown (the whole piece may have been donated by a king or prince as a devotional act, but the history is unclear).  The crown is kept at Hildesheim Cathedral in Germany on top of a reliquary statue of Saint Oswald made of gilded wood with disturbing niello eyes.

Oswald is a good illustration of the fungible nature of political and religious power.  He was a 7th century Saxon king who converted to Christianity and annealed the thrones of Bernicia and Deira together into the powerful Kingdom of Northumbria which was a high point in England’s dark age history (this business of putting kingdoms together out of disparate preexisting elements is reflected somewhat in the bricolage nature of  this saint’s crown from 500 years later).  Oswald was a warlord who died in battle, yet he was also a uniter, a spiritual leader, and a saintly king (at least in Bede’s estimation).  He became the focus of a particular cult later in the Middle Ages and there are at least 4 skulls attributed to him in continental Europe alone.