Technical Abstract: Photographs and descriptions of insitu geologic materials with known headcut erodibility index values are presented in order of increasing headcut erodibility index. These photographs and descriptions allow potential users to become familiar with the index and to obtain a rough estimate of index values for other materials through qualitative comparison nto those presented. Although developed in hard copy format as a training aid, the material has been converted to a hypertext format for release in electronic form (CD ROM) as an application aid for the Natural Resources Conservation Service SITES software. A hypertext browser with GIF grpahics viewing capability is required for optimal utilization of the material in electronic format.