Hunting the Magnetic Field
Webinar Format: Webex
Contact Ken Miller for Access Information
Speaker: Dr. Lisa Tauxe, Scripps Institution of Oceanography
Earth’s magnetic field has been the target of scientific investigation for over four centuries yet the basic fact that the field switches polarities, though suspected for over a century was not proven until the early sixties. This fact was key to the plate tectonic revolution and part of the rationale to begin drilling the ocean floor with the Deep Sea Drilling Project over fifty years ago. And the study of the Earth’s magnetic field has remained an integral part of ocean drilling throughout the history of endeavor.
In addition to flipping polarity, the Earth’s magnetic field changes both direction and strength on time scales from decades to millennia. Human observations of field directions provide constraints for field behavior since the age of maritime exploration starting in the 15th century but field strength measurements only started in the 19th century, so understanding of the geomagnetic field requires the use of “accidental” records such as sediments and igneous rocks. Because 70% of the surface of the Earth is covered by ocean, marine records are essential to get a global view of history of the Earth’s magnetic field and records beyond a few million years require ocean drilling.
Magnetic measurements on International Ocean Discovery Program cores continue to provide clues as to the timing and nature of magnetic reversals, attempted reversals (excursions), and the rise and fall in field strength since the Jurassic. Prof. Tauxe will share paleomagnetic results not only from her most recent experience on IODP Expedition 382 to the “Iceberg Alley” in the Scotia Sea but also from previous expeditions since DSDP Leg 73.