Almost circular in shape, largely bounded to the S by the Danube and to the E by its important tributary, the Prut, Romania occupies the eastern section of the Carpathian-Danube region. The large Romanian natural areas are harmoniously distributed in a concentric amphitheater; in the center is the Transylvanian plateau surrounded by the Carpathian chain, while on the outside the area of hills and plateaus passes through a strip of low plains that extend to the borders of the country: Wallachia to the S, towards the Danube, Moldavia to the E, towards the Prut. Finally, almost all of the Dobruja is included in Romania, an area of modest elevation between the terminal course of the Danube and the Black Sea. Cenozoic, when the Carpathian chain rose, which today dominates sedimentary expanses mostly belonging to the last period of the Cenozoic era (Pliocene) and to the Neozoic; there is no lack of outcrops of more ancient, paleozoic and mesozoic lands, well represented in Dobruja: indeed this rocky base forces the Danube to bend to the N, before flowing into the Black Sea.
According to findjobdescriptions, the essential morphological element is constituted by the Carpathians; raised during the mighty Alpine-Himalayan orogeny, they can be considered as a continuation of the Alps themselves, while at the so-called Iron Gates they connect with the Balkans. Their structure, however, is much less compact than the Alpine one, since the chain is formed in several orogenetic phases alternating with periods of peneplanation, which is responsible for the rounding of the peaks which represents, together with the lower elevation, one of the main elements of differentiation with the alpine reliefs. Although the Carpathians cover a large part of central-eastern Europe (Slovakia, Poland, Ukraine), Romania is the Carpathian country par excellence, including, of the three sections in which the chain is commonly divided, the entire southern stretch (or Transylvanian Alps) and almost all the oriental one. It is customary to consider the Prahova River Valley and the Predeal Pass as dividing elements between the Eastern and Southern Carpathians; in fact, the two sections present significant differences. The Eastern Carpathians consist of three roughly parallel chains, oriented mainly from N to S, of which the central one is formed by ancient rocks of compact crystalline schists and the lateral ones by Mesozoic sedimentary flyschformations (with sandstones, marls, etc.) resistant. A volcanic chain, the largest in Europe, leans on the western side, formed during the lifting of the Carpathian arc (Călimani mountains, Hărghita etc.), with a dense concentration of volcanic buildings, some of which are well preserved. The average altitude is 1200-1350 m, with the highest peak in Mount Pietrosu (2305 m) in the Rodnei group at the northern end of the chain; The fractionation due to both tectonic and erosive activity is very evident everywhere, which has created multiple depressions and a very varied landscape. The most picturesque regions, however, are those of limestone, where there are frequent karst phenomena and erosive manifestations. The Transylvanian Alps, whose course, from E to W, is perpendicular to that of the Eastern Carpathians, well justify the name attributed to them with their vigorous morphology. In fact, essentially made up of crystalline rocks, they have a more massive appearance, reveal a more intense glacial modeling and have higher peaks, exceeding 2500 meters in several points; Mount Moldoveanu, in the rugged massif of Făgăras (Făgărasului), reaches 2543 m. There are many passes, given the strong erosive action of the rivers that descend from both sides of the chain; the Olt (Oltul), a tributary of the Danube, has opened a furrow through the Transylvanian Alps, thus joining the opposing foothills plains.
The Romanian section of the Carpathian system includes another mountainous group, the Apuseni, or Western Mountains (for this reason these mountains are sometimes also called the Western Carpathians, which can cause confusion with the real Western Carpathians, the border between Slovakia and Poland.). Ancient block that the river Mures (Muresul), to the S, divides well from the Transylvanian Alps, fractured and deeply engraved by the rivers, the Apuseni massif is today considered an isolated fragment of the Carpathian system; it consists of crystalline rocks which are flanked, however, by recent volcanic reliefs, in correspondence with which there are numerous mineral deposits, already exploited in ancient times. Eastern Carpathians, Transylvanian Alps and Apuseni almost perfectly circumscribe Transylvania, which, as the name implies, forms a sort of open space “beyond the forests”, which, especially once, thickly covered the surrounding mountains. Tectonic sinking zone in which marine and fluvial deposits have accumulated, mainly Cenozoic, Transylvania is a plateau, or more exactly a set of hills alternating with wide valleys, high on average about 500 m and gently sloping towards the Hungarian plain which tends to drop down to 200 m, but from which it is largely separated by the Apuseni. Of the plains, which contribute just for a third to the formation of the Romanian territory, the largest and most important is that of Wallachia, which reaches the Danube from the southern slope of the Transylvanian Alps and which the great river has built with its recent floods. Another region outside the Carpathian arc – but in the Eastern Carpathians – is Moldavia, which the course of the Prut separates from the republic of the same name; partly flat, partly also hilly, Moldavia is made up of Cenozoic sands and clays alternating with more recent alluvial layers of the Neozoic. Banat, a monotonous plain that branches off from the last northwestern spurs of the Transylvanian Alps and morphologically fits into the great Pannonian lowland, E la Dobruja (of which the southern part is Bulgarian), a territory largely low and flat, but moved by hilly rises in the central-northern section. It is with the Dobruja coast that Romania faces the Black Sea for 234 km: the coast is characterized to the N by the tangle of the Danube delta, in the center by lagoons (limani) formed at the mouth of the rivers due to the sinking of the soils. in recent geological eras, while to the S the presence of a rocky escarpment overhanging the sea gives rise to a high and straight coastline.