Česky
Weathering and erosion of sandstone landscapes often results in many amazing landforms such as arches, alcoves (rock shelters), pedestal rocks and pillars. Long-term research has produced numerous contrasting ideas for the origin of these landforms. The presence of salt and/or occurrence of freezing water and/or similar potential weathering/erosion processes at site are common causes of these landforms. The effect of gravity loading stress has been overlooked or assumed to increase the landform’s weathering rate. Research at the Institute of Rock Structure and Mechanics is based on field observations of locked sands and cemented sandstones and on physical experiments, followed by a numerical modelling. This may be the first time that the landforms cited above were reproduced in laboratory experiments. The Institute interpreted its findings by a novel mechanical model called “the concept of locus of fabric instability.” The results clearly show that an increase in stress within the landform (fabric interlocking) reduces weathering and erosion. Material with insufficient loading is rapidly removed by that weathering process and the remaining load bearing landform structure is protected by the fabric interlocking mechanism. The Institute concludes that its research that planar discontinuities in sandstone and negative feedback between stress and weathering/erosion processes are sufficient conditions to create landforms.