Flysch and molasse 

GSA Bulletin
By:  and 



By definition European geologists consider a sequence of limestones, sandstones, and shales, the beds of which are thin, regular, and alternating, and which are deposited in a geosyncline or foredeep shortly before a major orogeny, as the flysch. The waste products that accumulate as a deposit flanking mountains and built in part of the deformed flysch make up the molasse. In field practice the groups of sediments called flysch and molasse, or facies of them, are formations in the American sense. However, the Europeans would not recognize all groups of beds deposited in a geosyncline just before an orogeny as flysch; the beds must possess the proper lithologic and bedding characteristics.

Europeans have tacitly tied the variable of lithology and stratification to the variable of orogeny, with attendant difficulties. Originally only the first was denoted, but later the second was emphasized in definition if not in field use. Americans have considered the terms chiefly in their orogenic sense and thereby have called certain sequences flysch that do not fully meet the requirements of European usage.

The writers are of the opinion that little is gained by the use of the words; by their application no new fact is told or discovery made. They simply elaborate a conclusion by way of analogy. On the other hand, a possibility of confusion is introduced by the use of the terms, and in America it is best to avoid them.

Publication type Article
Publication Subtype Journal Article
Title Flysch and molasse 
Series title GSA Bulletin
DOI 10.1130/0016-7606(1947)58[979:FAM]2.0.CO;2
Volume 58
Issue 11
Year Published 1947
Language English
Publisher Geological Society of America
Description 12 p.
First page 979
Last page 990
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