What is magnetic dating used for
By tracking and cross-dating past changes in the location of the magnetic field, geophysicists have reconstructed a series of magnetic polar positions extending back more than 2,000 years. At archaeological sites, hearths constructed of iron-bearing clays are ideal for archaeolomagnetic sampling because they were subjected to repeated hot firings.
Archaeomagnetic dating works because the earth’s magnetic field "wanders," continually changing its position in response to changes in the flow of liquid iron in the planet's core. As the clay cools, the alignment of the iron “fixes,” preserving a record of the magnetic field at a specific time in the past.In no way are they meant to imply there are no exceptions.For example, the principle of superposition is based, fundamentally, on gravity.Using these principles, it is possible to construct an interpretation of the sequence of events for any geological situation, even on other planets (e.g., a crater impact can cut into an older, pre-existing surface, or craters may overlap, revealing their relative ages).The simplest situation for a geologist is a "layer cake" succession of sedimentary or extrusive igneous rock units arranged in nearly horizontal layers.