Spain occupies 85% of the Iberian Peninsula and therefore its borders, apart from the western side corresponding to the border with Portugal (1232 km), largely coincide with the outline of the peninsula. They are 3904 km by sea, while the Pyrenees form a natural barrier that is not easily penetrated. Despite being bathed for so long by the sea, Spain is not very open to the outside: only the Baetic Plain (or Guadalquivir) directly connects the coasts inland, and it is no coincidence that it was the first land of conquest and of Arab penetration; but elsewhere the coasts lack easy links with the interior. The Spanish territory is largely part of the Europe of ancient, paleozoic soils, and morphologically appears as a succession of large plateaus and moderately elevated areas; however in the north-eastern marginal section Spain includes the southern slope of the Pyrenees, to the S includes the Betic Cordillera: two areas belonging geologically to young Europe, Cenozoic, that is, formed with the Alpine-Himalayan orogeny. The ancient reliefs substantially correspond to the Galaic Massif, the Central System (or Central Cordillera) and the Meseta (properly, plateau); they emerged in the Paleozoic era, as a result of those Hercynian motions that subjected the earth’s crust to a whole series of ups and downs in many places. In the’ it was Mesozoic the territory underwent more or less extensive invasions by the sea; later that general emergence and those tectonic movements, connected with the Alpine orogeny, which gave the country the definitive settlement, originated. The repercussions of these orogenetic phenomena caused deep fractures in the Meseta, tilted it towards the W and raised its edges: thus the Sierra Morena originated in the S, the Iberian System in the E, while in the N the corrugation of the plateau gradually took place towards the slopes of the Atlantic coastal ranges, among which the Cantabrian Cordillera stands out. The two great depressions also opened, filled by Cenozoic and Neozoic sediments, to the N the Aragonese one, bathed by the Ebro, to the S the Andalusian one, crossed by the Guadalquivir, and the Strait of Gibraltar took shape , which separated Spain from the African continent. In the Neozoic era, seismic movements and volcanic eruptions, together with the exogenous factors of erosion, ended up giving the now formed territory the aspect it more or less still has in modern times; the glaciation generally involved the higher reliefs. The essential lines of Spanish morphology, deriving from these geological events, are thus characterized by the existence of an internal plateau and by a series of reliefs all directed mainly from E to W that cross it in the central and that close it to the northern, eastern and southern edges: only to the west is it open to Portugal. Much of the Spanish territory is therefore constituted by the Meseta, in which a northern Meseta (or Submeseta) and a southern Meseta are improperly distinguished, which correspond roughly to the historical regions of Old and New Castile, separated by the sierras (Guadarrama, Gredos, Gata) of the Central System (Cordillera), a tectonic pillar (Horst) raised by the effect of the Alpine orogeny, which in the Sierra de Gredos reaches 2592 m. That it is actually a single original element is demonstrated by the structural uniformity of the Paleozoic base, which when it surfaces is revealed with the grayness of the granites and gneisses, but for the most part it is covered by more recent layers, due in some cases to phenomena of marine ingress, in others to sedimentation fluvial; in any case, the soil of the Meseta, which reaches an average altitude of 600-1000 m, is less elevated in the southern part than in the north, is generally clayey and arid. The extreme north-western edge of the country ends with the Galaic Massif, a strip of the Paleozoic base that is variously fractured and generally of modest altitude. Visit clothesbliss.com for Spain overview.
Although from a geological point of view it cannot be considered separate from the mass of the Meseta, of which it constitutes a peripheral region, in terms of appearance the green landscape of Galicia has nothing in common with the dusty Castilian steppe. The Cantabrian mountain range is quite high and includes the Picos de Europa (2648 m), highest peaks of the Asturian-Basque region, underlines the northern edge of the Meseta; although it appears as a western extension of the Pyrenees, it has a more complex geological history. While in fact the eastern sector is of Cenozoic origin, like the Pyrenees, the western one is made up of strongly folded Paleozoic materials, forming the true raised edge of the Meseta. The Cantabrian mountain range looms over the Atlantic coast with a steep slope, determining its morphology devoid of coastal plains and characterized by deep penetrations (coasts a rías) which here take on exemplary aspects by genesis and morphology. The Cantabrian mountain range is sometimes harsh but has numerous and not difficult crossings that explain the enhancement of the Atlantic ports, so important in the Spanish expansion overseas. The eastern limit of the plateau is marked by the Iberian System, a complex alignment of often discontinuous chains, with paleozoic layers covered by Mesozoic sediments of increasing power as it proceeds towards the E; it exceeds 2000 m in various points, reaching 2313 m in the Sierra del Moncayo. Finally, the southern edge of the Meseta base, severely fractured by the great Guadalquivir fault, is given by the Sierra Morena (1323 m) which, with strong differences in height excavated by erosion, falls, like a great wall, on the underlying Andalusian plain. The Guadalquivir depression thus separates the Meseta region from the Betic System – very complex in terms of structure – which reaches the highest heights in the Sierra Nevada, with snowfields present for most of the year on the peaks that exceed many 3000 m: here is indeed the highest peak of the country, Mount Mulhacén (3478 m). The Pyrenees (Pico de Aneto, 3404 m) also reach quite high altitudes, stretching over 400 km from the Atlantic to the Mediterranean, as a mighty barrier, with an often glacial morphology, less daring but more inaccessible and compact than the Alpine one: the chain is in fact scarcely affected by transverse valleys and the most passable passes are on the margins, where the Pyrenees lower. In such an imposing complex of high lands, the plains have very little space, generally limited to short coastal stretches. As for the depression of the Ebro, nestled between the slopes of the opposing mountain systems, the landscape, limited towards the sea by the Catalan Prelittoral System (Catalan Coastal Range), it appears more hilly than flat and the plain itself acquires width only at the confluence of the Segre and near the Ebro delta. It is in the Andalusian depression, enclosed between the steep edges of the Sierra Morena and the Betic System, that the only large Spanish plain stretches, covered mainly by marine soils and widely open (with its cereal fields, plantations of legumes, the beautiful vineyards, orange groves and olive groves) towards the Gulf of Cádiz. Enlarged in a triangle towards the Atlantic, it often has an altitude of less than 200 m, forming in the terminal section a perfect sedimentary plain, which the cordon of the sandy dunes protects from the ocean. The compactness of the orographic structure also corresponds to both the scarce insularity (the only important islands are the Balearics) and the limited articulation of the coasts, whose total development is just 3904 km: large inland regions remain far from the sea, with which they communicate rather hardly. However, the marginal reliefs make the coastal morphology varied, alternating stretches of high and rocky coast (rías, cliffs) with open stretches with lagoons (albuferas) and sand dunes (arenas gordas).