This book presents the results of the Third International Symposium on Observation of the Continental Crust through Drilling held in Mora and Orsa, Sweden, September 7 - 10, 1987. Volume 2 reviews new and general information on geology, geophysics, rock mechanics, geochemistry, drilling techniques and drilling problems in very deep holes of the FRG, USA and the Soviet Union. The proceedings are invaluable for earth scientists as well as for exploiters of geoenergy and other natural resources in the crust. Volume 1 summarizes the results of the Deep Gas Project in the Siljan impact structure, Sweden, including papers dealing with general aspects of astroblemes. It is of interest to all researchers working in the drilling industry and those interested in the problem of "deep gas."

The drilling site of the KTB is located on the western margin of the Bohemian Massif, a few kilometers south of the structurally important Saxothur ing ian/Moldanubian boundary of the central European Hercynian orogene and several kilometers east of one of the most important Permian-Mesozoic strike-slip zones of central Europe, the Franconian line. The borehole will be drilled in the Moldanubian segment (Fig. 1). o -::: --. . . . . . . . -. . -. D Il1O, Fig. l: Geological map of the Central Europe Variscides and location of borehole From geographical and political points of view, the drill site is located in northern Bavaria in the Oberpfalz province near the towns of Windischeschenbach and Erbendorf about 40 km southeast of Bayreuth. TARGETS AND RESEARCH TOPICS 'The Continental Deep Drilling program of the Federal Republic of Germany (KTB) is a project of basic geoscientific research. The program and goals of this project have been set by a board of the Senate Commission on Geosciences of the German Research Foundation (DFG). The technical concept of the drilling, sampling, coring and logging programs corresponds to these goals. The upper limit of the budget of 450 million DM is approved by the Federal Ministry of Research and Development (Bundesministerium fuer Forschung und Technologie).