A brief historical review of geological and geophysical research of the Antarctic continent is given. Methods of seismic, gravimetric and geomagnetic observations conducted by the First-the Fifth Soviet Antarctic Expeditions are described. The thickness of the Earths crust in the East Antarctica is determined according to Bouguer anomalies. It is found that the thickness of the crust about 35 km is prevailing on the larger part of the investigated territory and this is characteristic of a platform structure of the region. Some sections of the platform have undergone a considerable activization in the recent geological time. The activized sections are grouped into two types according to the thickness of the crust 1 Sections the activization of which was not accompanied by an increase of the crusts thickness. These are located mainly in the peripheral zone of the East Antarctic platform. 2 Sections the acticization of which was accompanied by a considerable increase up to 55 km of the Earths crust. These constitute the Gambourtsev Mountains.