FLYSCH

flysch, in geology, a remarkable formation, composed mainly of sandstones, soft marls and sandy shales found extending from s.w. switzerland eastward along the northern alpine zone to the vienna basin, whence it may be followed round the northern flanks of the carpathians into the balkan 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 flysch is not of the same age in every place; thus in the western parts of switzerland the oldest portions probably belong to the eocene period, but the principal development is of oligocene age; as it is traced eastward we find in the east alps that it descends into the upper cretaceous, and in the vienna region and the carpathians it contains intercalations which clearly indicate a lower cretaceous horizon for the lower parts. it appears indeed that this type of formation was in progress of deposition at one point or another in the regions enumerated above from jurassic to late tertiary times. the absence of fossils from enormous thicknesses of flysch makes the correlation with other formations difficult; often the only indications of organisms are the abundant markings supposed to represent algae (chondrites, &c.), which have given rise to the term "hieroglyphic-sandstone." the most noteworthy exceptions are perhaps the oligocene fish-bed of glarus, the eocene nummulitic beds in calabria, and the _aptychus_ beds of waidhofen. local phases of the flysch have received special names; it is the "vienna" or "carpathian" sandstone of those regions; the "macigno" (a soft sandstone with calcareous cement) of the maritime alps and apennines; the "scagliose" (scaly clays) and "alberese" (limestones) of the same places are portions of this formation. the _gris de menton_, the _gris d'annot_ of the basses alps, and the _gris d'embrun_ of chaillot appear in switzerland as the _gris de taveyannaz_. at several places the upper layers of the flysch are iron-stained, as in the region of leman and at the foot of the dent du midi; it is then styled the "red-flysch." lenticular intercalations of gabbro, diabase, &c., occur in the flysch in calabria on the pyrenees. large exotic blocks of granite, gneiss and other crystalline rocks in coarse conglomerates are found near vienna, near sonthofen in bavaria, near lake thun (wild flysch) and at other points, which have been variously regarded as indications of glaciation or of coastal conditions. foca (pronounced _fawtcha_), a town of bosnia, situated at the confluence of the drina and cehotina rivers, and encircled by wooded mountains. pop. (1895) 4217. the town is the headquarters of a thriving industry in silver filigree-work and inlaid weapons, for which it was famous. with its territories enclosed by the frontiers of montenegro and novi bazar, foca, then known as _chocha_, was the scene of almost incessant border warfare during the middle ages. no monuments of this period are left except the bogomil cemeteries, and the beautiful mosques, which are the most ancient in bosnia. the three adjoining towns of foca, gorazda and ustikolina were trading-stations of the ragusans in the 14th century, if not earlier. in the 16th century, benedetto ramberti, ambassador from venice to the porte, described the town, in his _libri tre delle cose dei turchi_, as _cozza_, "a large settlement, with good houses in turkish style, and many shops and merchants. here dwells the governor of herzegovina, whose authority extends over the whole of servia. through this place all goods must pass, both going and returning, between ragusa and constantinople."