The concept of soil geomorphology relies heavily on the summary and assessment,as weathering progresses,soil become reduced, in the sense that there is a reduction in it's average particle size. the potiential mobility of the soil increases as the particle size decreases and all reduced material above a local base level is metastable i.e vulnerable to removal.The maximum rate of natural denudation is the rate at which surface material which is almost but not quite mobile,becomes mobile,furthermore on any particular gradient there is a degree of reduction beyond which soil is too mobile to remail in situ.so the development of the landscape will be a function of this metastability of the soil,which is a function of the ease with which soil is detached and transported.Also the landscape development depends on the metastablility of the particular site which is a function of slope gradient and proximity to the next major break or change of slope on the slope profile.An encroaching pediment will therefore affect the soil on the upper surface long before that soil is affected physically by erosion.However analysis has shown that the relationship between gradient and degree of reduction applies only to those part of a slope on which there is no accumulation of transported material.The theory of soil geomorphology deals with the arrangement of landforms and the processes that have been or are shaping them geomorphological process may create disstinctive landforms such as erosion surfaces,which have a great influnce on soil type and superficial material in harness which is of greatest significance.Investigation of how landforms develop and of rates and result of processes has relied on the study of surfaces and sediments.