Abstract
Quantitative representation of the erosional stage of landforms is attempted by means of HRT (Relief) diagram. It is necessary for construction of the diagram to obtain the rela-tive height of ridge and valley floor as well as their difference (relief) to the available relief which can be calculated by substracting elevation of channel floor from that of summit-plane. Based on these values, any erosional topography is represented by a point in a triangular diagram named HRT (Relief) diagram. Stage or relative age of the topography is given quantitatively by the position of the perpendicular on the base-line of the diagram.
An application of the diagram was attempted for a hilly land to the east of the River Kako in Hyogo Prefecture, Japan. It is known from the result that almost a quarter of the whole volume has been removed by erosion. Assuming the age of Meimi gravel to be ca. 300, 000 years B. P., denudational rate of the hilly land is found to be 0.08mm/year, which is acceptable compared with the rate known for other regions by other methods.
