The electrical structure of mantle lithosphere Alan G. Jones Fossil structures within the mantle lithosphere contain clues to its formation and deformation processes. These strucutres can be imaged using geophysical methods, and predominently seismic techniques have been used. However, modern electromagnetic imaging, using high-precision magnetotellurics, offers an alternative, usually complementary, approach. This paper will present inferences from MT studies that can be taken about such processes, focussing particularly on the results from Archean cratonic regions.