Abstract
Loess might be identified by two index properties: the granulomere composition and the dry unit weight. These two indices are necessary but not always sufficient for identification of loess. The 0.01–0.05-mm fraction is predominant in typical loess. On the basis of analyses of samples from three continents, it was concluded that the 0.01–0.5-mni fraction deserves the name loessial fraction. Based on the loessial fraction concept, a granulometric classification of loess is proposed. Loess-like deposits possess loessial properties, but to a lesser degree than pure loess. There is a gradual transition from loess to loess-like deposits with loessial characteristics. For this reason, authors of research papers on loess use a multitude of adjectives to describe qualitatively the loess they study. The granulomere composition chosen as the first essential and nonarbitrary characteristic of loess and loess-like formations in this paper provides a definite borderline to delineate loess from loess-like sediments. In addition, the proposed classification of loess and loess-like sediments based on the relative amount of coarse and fine fractions provides a numerical definition of the adjectives clayey and sandy as applied to loess and loess-like deposits. A triangular chart is used to classify loess. This abstract has been accepted for publication at the 27th International Geological Congress, 1984, Moskow.
