About the So-Called Fluvioglacial Deposits and the Place of Diluvial Processes Take in the Lithodynamic Succession
The article deals with the existing definitions of fluvioglacial deposits that are chiefly developed in the mountain lands. It also points out the main contradictions in field and laboratory diagnostics of fluvioglacial deposits contained in the fact that lithologic criteria for such diagnostics do not exist in the nature. It refers to all the facies of fluvioglacial deposits in the pre-glacial zone. The absence of lithologic criteria of distinguishing between the so-called fluvioglacial and mountainous alluvium is explained by the structure of all these deposits. It is conditioned by hydrodynamic peculiarities of the floods in which they are developed. Pre-glacial fluvial sediments undergo the process of laying many times both immediately by the glacier margin and under the glacier itself. Thus, it means that according to the well-spread classifications all the melt-water deposits (except pre-glacial lake deposits) should be called «alluvium». Besides, it often happens that some forms of a principally different genesis-diluvial origin-would be taken for the deposits of melt glacier water. The former it their turn have been formed by cataclysmic (i.e. - temporary) floods from ice-dammed lakes which outburst. Unclear diagnostics of water deposits leads to the difficulties in defining criteria to seek alluvial placers. The article shows the place of diluvial deposits in the row of other genetic types of loose sediments. The second part of the article deals with the energy essence of the diluvial morpholithogenesis from the points of natural risks.
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Issue: 4, 2003
Series of issue: Science
Rubric: Geography
Pages: 80 — 85
Downloads: 990