Not all of these questions are universally important, nor is the list complete. The answer to these questions, however, can be important in satisfying the needs for the soil survey. Promising sources of reference material have been mentioned. The amount and significance of existing information varies widely, but in most parts of the United States it is substantial. Preliminary research can provide much, if not most, of the information about the soils of the area and their geography that is needed to start field studies and prepare a preliminary mapping legend.
Preliminary research provides the basic data for interpreting the soils.