In 1988, Ahnert presented a special type of land form classification, with which a connection has been established between the approximate age of forms of land with their morphological size.
During operations with large geomorphologic maps of scale 1: 25000, the following studies are necessary:

1- Statistical analysis of simulated models and preparation of a geomorphometric basis (frequency analysis, hypsometric distribution and characterization of correlation values)
2- Extraction of units of basis of land lays
3- Study of statistical aspects and adjacent morphology units
4. Analysis of existing profiles (electronic maps and examination of slope, curvature and shape elements)
5. Step-by-step tests of land
6. Modification of methods and classification of process