Suhard Massif. A geomorphological study

Abstract

Suhard Mts., part of the Northern Carpathians, stretch over an area of 323 sq km, in the shape of a  northwest-oriented ridge. This massif is composed of crystalline schists  (meso- and epimetamorphic), as well as sedimentary rocks pertaining to the trans-Carpathian flysch deposits (i.e. various types of sandstone, conglomerates and marls) in the southwestern sector. Whereas this region is characterized by the occurrence of a wide range of carbonate rocks, we noted the scarcity of karst forms. Geological survey maps of the area indicate the occurrence of few folded structures; moreover, the massif is mostly part of an ample anticline whereby the axis underlies the valley of Bistrita Aurie river, accompanied by a large syncline underlying Cosna river valley (tributary of Dorna river). The prevalence of crystalline rocks within this anticlinorium results in the overall massif shape of these mountains (hence, the name), which is the foundation for the detail structural and lithological relief forms. The array of structural relief forms includes structural plateaus on sedimentary and crystalline carbonate rocks, and steep slopes in the form of both hogbacks and overthrust scarps. The lithological relief occurs primarily as a result of the contrasting chemical composition of various crystalline rocks, whereas sedimentary rocks seldom generate such forms and solely when favored by the structure, as well. Consequently, carbonate rocks are rather discrete and only stand out in the form of clints (lapies) and gorges, or hums. As regards the matter of denudation surfaces, which has proved rather difficult to solve, we were able to determine the presence of an erosion surface ranging from 1200-1300 m to 1500-1600 m, wherein neotectonics played a significant role by fragmenting the original surface, particularly in the northwestern sector, where its fragments descend in the shape of consecutive steps towards Rotunda saddle. Periglacial modeling of the relief resulted in a variety of forms of both erosion (scarps, ridges, hums) and accumulation (scree) located in the highest areas, particularly along the main ridge (summit).