Die Verwitterung Basischer Vulkanite
In two weathering profiles on pyroclastic material several phases of volcanic activity were found. By means of different methods of investigation (microscopy, SEM and microprobe, X -ray, chemical analyses, determination of absolute ages) distinct eruption cycles could be based on various primary minerals and the secondary minerals fo~med by weathering processes were defined. Halloysite (in 10 A..- and. 7 A-modification) ...