Several mountain masses of considerable height occupy the centre of the country, and separate these riverine hills from the main range of the Pyrenees. They consist for the most part of chalk, through which the bounteous rivers descending from the Pyrenees have excavated their beds. These channels, with their precipices, defiles, and cascades, form one of the most picturesque mountain districts of Spain. The most famous of these Pyrenean foot-hills is the Sierra de la Peña, which is separated from the Pyrenees by the deep valley of the Aragon. At the eastern extremity of this chain, high above the ancient city of Jaca, rises the pyramidal sandstone mass of the Peña de Oroel (5,804 feet), from which we are able to embrace an immense horizon, extending from the Pyrenees to the Moncayo. The wild district which occupies the centre of this magnificent panorama is the famous country of Sobrarbe, held in high veneration by patriotic Spaniards, for it was there they commenced their struggles against the Moors.
MONSERRAT, CATALONIA.
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An elevated saddle connects the Sierra de la Peña with the irregular mountain mass of the Sierra de Santo Domingo, to the south of it, whose spurs descend in terraces into the rugged plain of the Five Towns. It is separated by a narrow cleft, through which passes the Gallego from the Sierra de Guara, which extends to the river Cinca in the east, and several minor chains run parallel with it. This parallelism in the mountain ranges may be traced, likewise, as far as the river Segre.
The Monsech, thus called from its arid calcareous ravines, presents the appearance of an unbroken rampart from the south, but is intersected at right angles by the gorges of two Nogueras—the Ribagorzana and Pallaresa. The Peña de San Gervas and the Sierra de Boumort, which rise to the north of it, are much less regular in their contours, but exceed it in height.
The Pyrenees terminate with the gigantic mountains surrounding the valley of Andorra, and with the Peak of Carlitte (9,583 feet). The Sierra del Cadi (8,322 feet) belongs to a detached chain hardly inferior to them in height, and culminating on French soil in the superb pyramid of the Canigou (9,140 feet). Numerous spurs extend from this sierra towards the sea.
In this rugged mountain region we meet with geological formations of every age, from the Silurian to the cretaceous. Iron, copper, and even gold abound, and might be worked with great profit if roads and railways penetrated into the upper valleys. A coal-field on the Upper Ter, near San Juan de las Abadesas, is being worked very sluggishly, and others on the western slope of the Cadi have not even been touched. The famous rocks of salt at Solsona and Cardona lie at the foot of the Sierra del Cadi, and that of Cardona alone, though it has been worked for centuries, is estimated to contain nearly 400,000,000 cubic yards.
The abundance of mineral veins is due, perhaps, to the existence of subterranean lava lakes. The only volcanic hills in the north of Spain are those near Olot and Santa Pau, in the upper basin of the Fluvia. Immense sheets of basaltic lava have been ejected there during the tertiary age from fourteen craters, one of them, upon which stands the old town of Castelfollit, forming a huge rampart of picturesque aspect. Jets of steam issue even now from many fissures in the rocks.
The mountains along the coast of Catalonia resemble in every respect those of Valencia, from which they are separated by the gorge of the Ebro. Near the mouths of that river the rugged and mountainous region extends about thirty miles inland, as far as the Llanos del Urgel; but farther north it widens, until it finally merges in the spurs descending from the Pyrenees. The principal summits are the Mont Sant (3,513 feet), the Puig de Montagut (2,756 feet), the Monserrat (4,057 feet), and Monseny (5,276 feet). The best-known passes are at the head of the Francoli, through which runs the railway from Tarragona to Lérida, the pass at the head of the Noya, and the Pass of Calaf.