Ancient Romania had as its border the main ridge of the Carpazî; the new one has about half of the chain itself, which crosses it for a length of 600 km., dividing it in almost two equal parts. Romania can therefore now be ascribed to both the Carpathian states and the Danubian ones.
According to ehotelat, the continuity of the Carpathian system with respect to that of the Alps is well known: the Carpathian arch, which extends the Austrian Eastern Alps, from which the Vienna basin separates it, is in turn continued, beyond the Iron Gates, by that Balkan. This whole complex belongs to the era of tertiary corrugation chains. The Romanian Carpazî, less high than the Alps (maximum altitude 2540 m.), However, like them include nuclei of ancient soils, more or less completely metamorphosed, incorporated into the complex of tertiary wrinkles (see Carpazî, IX, pl. XXXIX and XL). To them we must reconnect the massif of the Bihor Mountains, which, with its main arch curved from Bucovina to Banat, encloses the Transylvanian Basin, a region of hills carved in uncorrugated Neogenic soils. The Carpathian regions as a whole represent 124,000 sq km, that is 42% of Romania. This elevated country is surrounded by plains and hills that extend for about 137,000 sq km, or 47% of the country.
In the interior of the Carpathian arc, the alluvial plain of the middle Danube, a large sinking region commonly known as the Hungarian Plain, does not remain completely alien to Romania, which occupies its eastern edge up to a border established in such a way as to secure the main cities, Satu-Mare (Szatmár), Oradea-Mare (Nagy Várad), Arad and Timişoara (Temesvár).
Around and outside the Carpathian arc lie the plains or hills of Moldavia-Bessarabia to the east, and Wallachia to the south. The uncorrugated Neogenic soils are found here, probably resting everywhere on an ancient plinth, with the intermediary of the horizontal Cretaceous period. Deeply hidden in the southern part, where the deepest perforations did not cross the Cretaceous period, this hoof is closest to the surface in the eastern part, where the Bessarabia attaches itself to the Russian platform, and where the recessed meanders of the Dniester are carved, through the layers. horizontal primaries, up to the archaic (Jampol rapids). But this outcrop is very limited and the geologically oldest region of Romania remains Dobruja, of which the northern part,
The Dobruja. – Overall, it is a 200 km long shelf stretched like a kind of embankment, between the Black Sea and the swampy valley latitude of Constance, ever wider and higher towards the south (260 m.), And even higher towards the north, so much to assume the character of small rugged chains (Pricopan, 415 m.).
To the south the ancient base is not visible: in the so-called Quadrilateral, about 150 km wide, the Cretaceous plateau of the Bulgarian platform extends, furrowed by deep valleys that descend to the Danube. A layer of Neogenic limestone (Sarmatic) covers it, making the table even more arid: cut into picturesque banks by marine erosion towards Balcic, to the north it progressively lowers, always covered by a veil of löss, up to the arid Medjidia valley, through which passes the railway that connects Bucharest to Constanta.
Continuing northwards, from this mantle of löss you can see reliefs of ancient rocks, schists and primary sandstones more or less transformed, granite and porphyry, which form crests oriented from north-west to south-east, according to the direction of the folds of the Cimmerian chain, while the sandstones of the Triassic and the Cretaceous, both in transgression, form large tables. The boldness of some peaks of granite or porphyry or quartzite is in contrast with the gentle slopes of the vast depressions that separate them. These very worn reliefs were revived by a movement that raised the Dobruja pillar to the north-west at the end of the Tertiary, and by an erosion that began again in conditions of a drier climate than today.
The geological interest of these high hills of Dobruja goes beyond the horizons that they allow to discover. This isolated testimony of the ancient Cimmerian range must undoubtedly be linked to the Crimea and the Caucasus, while its extension, buried under the sandstone ridges of the Moldovan flysch, is revealed in the abundance of green rock pebbles, characteristic of Dobruja, found in the tertiary conglomerates.
Hills of the Transylvanian Basin. – The Transylvanian Basin, a region depressed in comparison with the mountains that surround it, is however far from being a plain. The differences in level between the valley floor and the neighboring peaks often reach several hundred meters. But all this relief is the work of a basic erosion of the Hungarian and Wallachian plains. The material affected by the erosion offered weak resistance, being formed by clays and neogenic sands with some rock salt lenses and some not very thick sandstone banks, generally resting on Eocene or Oligocene layers, which appear to the west and north on the edges raised due to of the orogenetic uplift, while to the east the Tertiary disappears under powerful eruptive accumulations, which determine only the peaks exceeding 1000 m.
A general note is the monotony of the relief: wide flat-bottomed valleys with terraces, slopes that rise in a gentle slope, with irregular slopes due to the sliding of the sands on the clays, rounded ridges, sometimes interrupted by the steep banks produced by these slips. The presence of rock salt makes these phenomena more frequent in the region extending east of Cluj (in Romanian Câmpia, meaning “bare countryside”).
The Paleogenic form higher hills at the foot of the Bucovina Massif and also at the edge of the Bihor west of Cluj, since the inclination of the layers produces asymmetrical crests of the cuestas type. There is no such thing in the south and east. It seems that a relative subsidence movement made itself felt until the end of the Tertiary sector; some lakes persisted up to the Levantian. The Olt meanders in the midst of alluvial plains staggered from 400 to 800 m. (basins of Făgăraş, Treiscaune and Ciuc), undoubtedly due, like the lakes that preceded them, to the damming by the volcanoes. These are formidable eruptive apparatuses, which form a real chain aligned on the axis of the sunken crystalline massifs, over a length of 130 km. The age of the eruptions seems older in the north, where the reliefs are higher and more desiccated by erosion (Petrosul 2102 m.):south of the Hargitta (1798 m.) the flows begin to be identified, and finally small craters appear, just as fresh as those of central Italy, for example. the one where the St. Anna Lake near Tuşnad shines.
Plains and hills of Moldavia-Bessarabia. – The foreland of the Carpazî has a completely different aspect to the east and south. The relief is more rugged, still reaching about 400 m. between the Prut and the Dnestr: the structure appears more complex.
Two great facts dominate: the presence of the Russian platform, raised to the north until it reaches the recessed meanders of the Dniester, and the influence of the Carpathian corrugations. The first fact determines the hydrographic network, formed by numerous rivers, descending towards the south; the second is probably responsible for the formation of the furrow of the Siret and the raising of the hills above 400 m. between Roman and Chisinău. All the topographical details are however due to the erosion of the Neogenic layers (sands and clays with one or two thin intercalations of Sarmatic limestone layers) inclined from north to south with sufficient regularity, without noticing a significant difference between Bessarabia and Moldova proper.
The distinction that is imposed is that of southern plains, high central hills and northern plateaus. To the south, Moldavia, more depressed, extends the collapse area of Galaţi, with floodplains and arid löss terraces; Bessarabia offers a wider base, with a more pronounced inclination, known under the Turkish name of Budgeac, in which the steppe extends over the broad ridges of löss between the humid valleys that end in liman.
In the center, the ground rises and a dense network of valleys carves the sands and clays in ridges that go beyond 500 m. in Moldavia (593 m. near Hârlău) and reach 475 m. in Bessarabia (Codru Bâcului). A peak of the cuestas type develops in an arc of a circle open northwards from Hârlău to Bălţi, passing through Târgu-Frumos and Iaşi: the Prut seems to have opened a consequent furrow.
To the north, the relief becomes more monotonous, with the exception of ancient Bucovina, where the influence of the Carpazî translates into an elevation of the layers that gives rise to high hills carved in cuestas near Cernăuţi (576 m.). Everywhere else you find yourself in front of a plateau of 250-300 m. above sea level, where the löss more or less veils the Sarmatian clays and limestones: the primary base, covered by the Cretaceous period of the Russian platform, is so close to the surface that the Dnestr bares it everywhere between Hotin and Soroca.
The edge of the Hungarian plain. – The description of the relief would not be complete without a few words about the plains area, on which the Romanian territory lies west of the Banat and Bihor mountains, a small entirely Quaternary foothills plain, probably in the process of sinking. The rivers have rambled there on vast dejection fans, cut into terraces at the mouth of the mountain, particularly in the surroundings of Lugoj (Timiş) and Arad (Mureş). To the north of Oradea-Mare and to the south of Timiş0ara there are ancient abandoned, marshy beds, often flooded after the spring rains: the soil is sometimes too dry and too wet, especially in the Banat plain.