List M - Soils
These thesaurus lists, lists A-R, are used by GeoRef indexers for selecting index terms and by searchers for additional information not necessarily found in individual term records in the body of the Thesaurus. In most cases, an hierarchical list is given. In some cases, an alphabetical or other list is provided.
The notes under Searching attempt to guide the searcher in the use of the list. Searchers might also read the notes on Indexing for further clues but should be aware that these notes reflect current practice which in some cases differs from past practice. Further notes on specific terms are in the body of the Thesaurus and additional notes on searching are in the GeoRef Thesaurus, 11th edition Introduction section on searching beginning on page x. Information specific to searching and the individual list topics is included, e.g., a section including soils begins on page xii.
Under Indexing the current indexing practice is given. These notes should be read along with the instructions under the individual terms in the body of the Thesaurus.
The classification of soils has undergone several changes in American practice. Two of the classifications used are detailed in the lists American Soil Classification System - 1938 and American Soil Classification System 1965 et seq. (Soil Taxonomy). There are many other classifications of soil used. In GeoRef index terms, we allow use of taxonomic names from a classification system, e.g. Hapludults, when they are provided rather than local names or soil series mapping units such as Sassafras series. In addition to the two lists, there is a third list of German and French Equivalents of English Terms which includes names from the two American classification systems as well as some common names from other classification systems.
To search for a soil group, one must search for all possible varieties, including different names in different classifications and in different languages. For example, to search for Latosols, you must also search for Sol-ferralitique. The American names have been used most commonly in GeoRef indexing.
Use the soil classification terms given in the source documents. Do not attempt to interpret types of soil according to one of the available classifications. The list of German and French Equivalents of English Terms may be used to translate from those languages.