What is the theory of pediplanation and the theory of etchplanation in slope development?

The theory of pediplanation suggests that slopes are developed by the gradual lowering of a land surface due to weathering, erosion, and mass wasting processes. The theory of etchplanation, on the other hand, proposes that slopes are formed through the selective removal of material by chemical weathering and erosion, such as through the dissolution of rocks or minerals. Both theories contribute to our understanding of slope development in different geological contexts.