The present book is devoted to the study of the deep Earth's interior structure, one of the most important problems of Earth sciences today. The drilling of the Kola superdeep well inaugurated a new stage in the study of the Precambrian continental crust. The well was sunk in the northeastern part of the Baltic Shield, in an area where the Precambrian ore-bearing structures, typical of the ancient platform basements, are in juxtaposition with each other. To the present the well has been drilled to a depth of 12 km, has traversed the full thickness of the Proterozoic complex and a considerable...