This book is addressed mainly to younger geoscientists and students of geologically related subjects. It discusses: (1) the concepts, definitions and experience of strength, particularly rock strength, with application of experimental techniques; (2) the physical-chemical aspects of the strength of pure phases; (3) strengthening of grain packings by "intermolecular forces"; (4) the behaviour of Buntersandstone samples underwater and lessons for understanding weathering processes; (5) deductions concerning the distribution of substances and forces in Buntersandstone samples from observing the response of samples underwater.The urgency of environmental studies has been the main driving force for this book. The discussion of single problems is wide-ranging, particularly for chemical and physical topics, so as to enhance the reader's understanding. The book is more a research account than a textbook. Thus, no "completed", well-defined subject area is presented; on the contrary, many questions are raised which should form the basis for future research. The book has been written to stimulate lively debate.