It is the only geographical region that possesses clearly defined limits for natural accidents as they are the rivers Uruguay and Paraná that, next to some of their tributaries, they separate it of the plains pampeana and chaqueña and of the republics of the Paraguay, Brazil and Uruguay. They can be pointed out highly in her four subregiones different: the missionary plateau, the tidelands and lagoons correntinas, the kitchen knives correntino-entrerrianas and the delta. The missionary plateau constitutes the maximum elevation of the area (800 m) corresponding to the southern border of the solid one of Brasilia with gritty red and meláfiros, of arched surface traveled by serranías of scarce height, clipped by numerous rivers and streams that form jumps and cascades when finding the meláfiro, standing out the arch of the waterfalls of the lguazú.
It enjoys a subtropical climate without dry station, with superior precipitations to the exceptional annual and icy 1.600 mm that originate a dense forest where they stand out araucaria copies, jacaranda, lapacho and guatambú that give place to an important forest exploitation.
In spite of the value maderable of these trees, the one that has promoted the colonization of this area is the dull herb that is presented more or less in groups extensive amid the forest. Today it cultivates it to him on wide previously subjected areas to it dismounts and where they have also been introduced citric, tung and tea that it has found good conditions of floor here (laterítico) and climate.
The intense reforestations carried out especially with diverse types of pines, of those that one obtains cellulose, serve from base to the industry papelera.
To the West of the river Aguapey is presented a low area and inundable where they stagnate the rain waters forming tidelands and lagoons, the biggest is those of lberá and that of Moon. The tidelands are skirted by a series of dunes of sand making the drainage of the very imperfect area. Lagoons and tidelands are distinguished because the first ones present their mirror of free water, as long as these have it covered with aquatic vegetation.
The corners or high areas, as well as the coastal areas of the rivers Paraná and Uruguay, they are the only ones profitable permanently; in them they settle the stays that lead the livestocks to pasture in the area of the tidelands in dry seasons. In these areas they are also carried out cultivations of dull herb, cotton, tobacco, rice and citric.
In the South of Corrientes is Mercedes' plateau, worked in Mesozoic, specially gritty rocks and it constitutes a center dispersor of waters and a sector of certain cattle aptitudes, especially for the ovinos.
Toward the South they are presented a series of drops that don't overcome the 100 meters, product of the conjunction of recent tectonic movements of ascent and of the fluvial erosion. The most important are those “kitchen knives” Grande and of Montiel that continue forking toward the South until ending up determining four at least dividing of waters that separate the valley of the rivers Paraná and their flowing Nogoyá and Gualeguay; Gualeguaychú and their collector Uruguay.
The warm climate with a brief period of icy and abundant rains in the North (more than 1.000 mm) you restitution tempered in the South, resembling each other to that of the plain pampeana. The vegetation is presented in park form and it follows the course of the rivers forming forests in gallery, being the predominant copies the urunday, the espinillo and the pruning.
They are also yatay palmares and caranday and in the fields, gramineous; the open mounts and the fields have been favorable for the cattle raising, I didn't seize the palmares because the livestock injures with the thorns of the palm. Although an important number of heads exists of bovine and ovinos, as well as of corral birds, the agriculture constitutes the predominant activity, being cultivated diverse cereals, oleaginous and forrajeras as well as citric fruits.
Between the town of Diamante and the river de la Plata, expands the inferior course of the river Paraná, in a labyrinth of islands, streams and channels that constitute their delta. The process of sedimentation of the particles suspended in the waters begins with the formation of banks that usually stop the floating vegetation of the "camalotal."
Later on the appears "juncal" when the sedimentation that goes elevating the land on which take root grarníneas and marshy species as the reed-mace that constitute the increasing "pajonal". Then, when consolidating the land, they settle the species of the "ceibal" where the ceibo prevails, being also lecherón, sarandí and some bushes that multiply until conforming the "it mounts white" or riverside forest to which are added laurel, higuerón, the palm pindó and the tacuara, besides climbings, lianas and epífitas.
The islands are depressed in the center, containing many times a lagoon in the interior, with the borders risen by the albardones where notices the arboreal vegetation. The floor aluvional is favorable for the plantation of species maderables like the poplar and the sallow, as well as formio and fruit-bearing, among those that the peach and the citric fruits stand out; during the periods of bajante the islands are dedicated to the shepherding. The delta has engendered a form of own life, where the boat is the only means of mobility of the islero whose activities link it to the coast.
Although for their limits the region mesopotámica pretends to be isolated, the man has been able to integrate it to the rest of the country and the nations that limit it by means of the construction of the tunnel subfluvial "Hernandarias" and numerous bridges like the complex Long Zárate-arm, the bridge "Grl. Manuel Belgrano", that of the "Liberator Gral. San Martin" and the recently inaugurated one "Padre Roque González."