The evolution of the profile paradigm in the history of pedology and quaternary geology: Concepts and applications.

摘要

The soil profile concept in pedology and the weathering profile in Quaternary geology are essentially the same, but have been treated in ways to cause interdisciplinary conflict and confusion. The purpose of this study was (1) to research the history of the conflict and confusion through elucidating the evolution of the soil profile and weathering profile concepts, and (2) propose a unifying profile concept, the pedo-weathering profile, that would attempt to resolve these interdisciplinary issues by facilitating the communication of soil information across disciplinary boundaries.; The soil profile concept, symbolized by A-B-C, developed first in Germany and Denmark, and then Russia in the 1870s. It did not reach the United States until 1914 and was not incorporated into earth science thinking until the 1920s. In 1923 prominent pedologists and Quaternary geologists defined profile-based zones of study. The soil or pedological profile emphasized the solum, the A and B horizons, and de-emphasized the subsolum region, the C horizon and below. In contrast the Quaternary weathering profile emphasized the subsolum region and de-emphasized the solum.; This study proposes a unified profile paradigm through the introduction of the pedo-weathering profile (PWP) concept. The pedo-weathering profile demands a re-examination of the pedological subsolum region; a region that has been studied closely by Quaternary geologists. The PWP subsolum contains a C horizon concept of more precisely defined scope than that traditionally used in pedology. In the traditional sense the interval between the solum and bedrock is designated as the C, whether pedogenically modified or not. In the PWP, the C horizon is limited to the part of the traditional C that is pedogenically altered. That part of the subsolum unaltered by pedogenic processes and not having the hardness of bedrock (R) is redefined here as the D horizon. These subsolum horizons exist worldwide in all terranes where fresh geologic materials are exposed at the earth surface and become modified by pedogenic processes; they are the evidence for land surfaces throughout the geologic record. The PWP concept should be useful in disciplines that, in reality, have overlapping interests with pedology.