Paleomagnetism is the study of the terrestrial magnetic field recorded by rocks at the time of their formation or during relevant geological processes that took place afterwards (e.g. metamorphism). It is based on this three basic assumptions:

• Axial geocentric dipole: The terrestrial magnetic field is similar to that produced by a geocentric dipole that is parallel to the rotational axis of the Earth (at least the mean over a specific period of time). Therefore, the paleomagnetic poles calculated within a specific area will coincide with those of the rotational axis.
• Record of the primary magnetic field: The ferromagnetic minerals contained in rocks can record the past terrestrial magnetic field.
• Unchanged record over time: The magnetization acquired by a rock at the time of its formation may remain unchanged over time.

The laboratory deals mainly with magnetic stratigraphy issues (reverse polarity), rock magnetism and anisotropy of magnetic susceptibility in various sedimentary environments.

Individual samples (of up to 12 cubic centimeters), or 2 x 2 cm probes of 150 cm in length, are used to obtain records of a higher resolution and greater continuity. Furthermore, the characterization of the remanence-carrying magnetic phases in rocks and sediments is carried out, along with the study of sedimentary fabrics based on measurement of the preferred orientation of minerals (AMS).

At present, laboratory techniques, along with superconductive instruments, make it possible to precisely establish the orientation, polarity and intensity of the record for almost any type of rock, thus obtaining highly valuable information of two different kinds:

Geochronology: The sequence of changes in magnetic polarity (called inversions) makes it possible to date local stratigraphic sequences. Paleo-orientation of geological bodies: The deviation of the orientation of the magnetic field recorded in rocks in relation to the expected benchmark enables the reconstruction of the deformation processes on different scales.