If one of these events were to occur today, modern society could be destroyed by the effect of CMEs on electronics.
This event did not occur at all during a 40-million-year period during the Cretaceous, known as the Cretaceous Superchron. A similar phenomenon occurs in the sun with greater periodicity than on Earth, and is largely responsible for the sunspot cycle. If one of these events were to occur today, modern society could be destroyed by the effect of CMEs on electronics. These events are believed to be the result of irregularities in iron convection in the outer core. A test proposed by Vine, Matthews, and Morley based on the existence of this phenomenon provides the most convincing evidence for Hess's hypothesis of seafloor spreading, since a certain property that changes each time one of these events occurs is crystallized in seafloor igneous rocks at the time of their solidification. The most recent of these events occurred 780,000 years ago, and was named for Brunhes and Matsuyama. For 10 points, identify these events wherein the polarity of a certain global field interchanges North and South over the course of thousands of years.
This event did not occur at all during a 40-million-year period during the Cretaceous, known as the Cretaceous Superchron.
{geomagnetic reversals} [or {reversals of Earth's magnetic field;} or reasonable equivalents]