FLYSCH, the term long used in geology to denote a peculiar formation occurring specially in the northern Alpine zone. In the Swiss-German dialect it means "slippery earth"; it is applied typically to very thick, light grey shales with intercalations of small beds of ferruginous sandstone and calcareous nodules. When modified by the predominance of calcareous or sandy elements it is usual to refer to "calcareous flysch," "sandy flysch," etc. The flysch extends from south-west Switzerland eastward along the northern Alpine zone to the Vienna basin, whence it may be fol lowed round the northern flanks of the Carpathians into the Bal kan peninsula. It is represented in the Pyrenees, the Apennines, the Caucasus and extends into Asia; similar flysch-like deposits are related to the Himalayas as the European formations are to the Alps. The deposits were laid down along the fringes of the great geosynclinal basin (the Tethys) which persisted from Jurassic until late Tertiary times. The flysch is not therefore of the same age throughout ; the oldest portions, such as those in the Car pathians, are lower Cretaceous but the greatest development was in upper Eocene (Priabonian or Bartonian) times and lower Oligocene. The absence of fossils from enormous thicknesses of flysch makes the correlation with other formations difficult. Local phases of the flysch have everywhere received special names—such as the Vienna or Carpathian sandstone. Large exotic blocks of granite, gneiss and other crystalline rocks in coarse conglomerates have been variously regarded as indications of gla ciation or of coastal conditions. (L. D. S.)