Premium
Mineralogical Methods in Soil Research: Part I. The Correlation of Soil Types and Parent Materials, with Supplementary Information on Weathering Processes
Author(s) -
Marshall C. E.,
Jeffries C. D.
Publication year - 1946
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1946.03615995001000c00068x
Subject(s) - citation , soil water , weathering , state (computer science) , library science , geology , archaeology , soil science , history , computer science , geochemistry , algorithm
T~»HE present report is strictly limited in scope to j. those methods which provide direct answers to certain problems encountered in soil survey and classification. The first problem concerns the establishment of the parent material. Field evidence is not always adequate, particularly where mixing may have occurred, and even detailed mechanical analyses sometimes fail to show clear relationships. The more advanced the stage of weathering, the greater these difficulties become. Semi-quantitative study of the resistant heavy minerals provides an exceedingly powerful tool, which, so far as the authors know, has never yet failed to give a clear answer. The second problem concerns soil maturity or stage of weathering. Certain minerals which slowly decompose under humid weathering conditions, by their variation in amount throughout the profile, provide a qualitative clue to maturity. This information is furnished in part by the heavy minerals (common hornblende and apatite are well known examples), but most of all by the constituents of the lighter fractions—the micas, feldspars, and quartz. For many purposes these methods should prove adequate in themselves. They may, however, also be used as essential preliminary steps in the precise quantitative study of processes of soil formation and development. They enable the pedologist to reject soil profiles whose quantitative study would be vitiated by the presence of geological or when combined with accurate mechanical analyses, of depositional differences. The procedures outlined are tentative, since so far they have only been used on a limited number of soils. The authors would appreciate suggestions for improvements or modifications. They have tried to provide a flexible framework which can be filled in and extended as our experience grows. Since few laboratories have so far undertaken this work some observations on general requirements are perhaps pertinent.