Chap. XV
Morosaglia, Seat of the Paolis.—Higher Valley of the Golo.—Orography of Corsica.—Its Geology.
On crossing to the right bank of the Golo at Ponte Nuovo, we enter the canton of Morosaglia, the former piève of Rostino, and the home of the Paoli family. The canton takes its present name from a Franciscan convent, still standing, and part of it used as an elementary school, founded by the will of Pascal Paoli.
It is about two hours’ walk from Ponte Nuovo to the hamlet in which the Paolis were born. The house is one of those gaunt, misshapen, rude structures, built of rough stones, and blackened by age, which one sees everywhere in the mountain villages; without even glass to the windows. Standing on the craggy summit of an insulated rock, the access to it is by a rough wooden staircase. Here Pascal Paoli resided, as a simple citizen, after the manner of his fathers, polished as his manners were, and highly as he was accomplished, after he had attained to almost sovereign power. The rooms are so small that he transacted public business in the neighbouring convent of Morosaglia.
There also his brother, Clemente Paoli, had a cell to which he often retired. His was a singular character. Of a saturnine cast of disposition, he seldom spoke to those by whom he was surrounded; a great part of his time was spent in religious observances, and in the practice of the most rigid austerities. In short, he was the monk when at home, and the most intrepid warrior when engaged with the enemy of his country. The sanctity of his private life procured him singular veneration, and his presence in battle produced a wonderful effect on the patriots. Even when pulling the trigger to destroy his enemy, he is said to have prayed for the soul of his falling antagonist.20 After the fatal field of Ponte Nuovo, declining to follow his brother to England, he spent twenty years in prayer and penance in the Benedictine Abbey of Vallombrosa, that shady and sequestered retreat in the heart of the Apennines, returning to his native Corsica only to die. Such was Clemente Paoli. Of his brother Pasquale, a fitting place for some more extended notice will be found at Corte, the seat of his island throne.
The country on the right bank of the river is rugged; rude paése crown the heights, and the hollows are shrouded in magnificent chestnut woods. The mountains seen from beyond Bigorno shut in the valley of the Golo so closely in some places, that it is a mere defile giving passage to the river and the road. The river is a torrent, and the valley is ascended at a sharp angle. At Ponte à la Leccia, we recrossed to the left bank of the river; the valley expanded, and there was much cultivated land, though the soil was poor. Rounded hills in the foreground were backed by a serrated range of mountains, Monte Rotondo being just visible.
Approaching now, through the high valleys, the central region of the mountain system of Corsica, this may be a proper place for a brief survey of the main features in its orography and geological structure. We have hitherto spoken of a central chain and its ramifications in a loose manner; but it would be desirable to convey more precise ideas of the structure of this mountain island; and, as the system happens to be very simple and intelligible, it affords an example, on a small scale, which may give the unscientific reader a general idea of the nature of grander operations. Having traversed the island from north to south, and from east to west, not without an eye to its general structure and composition, though making no pretensions to exact scientific knowledge, I may be able to furnish a not unfaithful digest of the observations of the foreign geologists Elie de Beaumont, Raynaud, Gueymard and others, as I find them quoted in Marmocchi’s work.
OROGRAPHY OF CORSICA.
At first sight, Corsica presents the aspect of a chaos of mountains piled one on another, with their escarped sides rising from the sea to great elevations; but on a closer examination, and with the assistance of an accurate map, it is soon perceived that these mountains, apparently heaped up in wild confusion, are distinctly arranged in three principal directions,—from north-east to south-west, from north-west to south-east, and from north to south.
The point which forms the main link of the whole system lies high, near the snowy sources of the Golo. This elevated part of the island, with the districts immediately surrounding it,—an Alpine and forest region in which the principal rivers and streams take their rise,—this region so sublime in its vast solitudes, so poetic, so savagely wild, so picturesque,—may be called the Switzerland of Corsica.
From this central link two great chains, forming, so to speak, the backbone of the island, diverge in opposite directions. One section, tending to the south-east, traverses the centre of the island, where the Monte Rotondo and Monte d’Oro lift to the skies their ever snowy peaks, and terminates at the Monte Incudine. This high chain throws out its longest branches to the south-west, each of them forming at its extremity a lofty promontory washed by the Mediterranean, and the successive ridges inclosing delightful and fertile valleys.
The other section of the central chain describes a curved line to the north-north-east, as far as Monte Grosso; and, over the Bevinco, links itself with the system of Capo Corso by the offsets of Monte Antonio and San Leonardo, by which latter col we crossed the ridge on the evening of our landing in Corsica. The spurs from this second chain take, in general, a north-west direction towards the sea. Less considerable than those connected with the first, they inclose narrower valleys, and form promontories less saillants, and of inferior elevation on the western coast.
The mountains of Capo Corso, extending in a chain nearly north and south, at a short distance from the east coast, form the third orographic division of the island; this chain, as observed in a former chapter, being cut by deep valleys of short extent, the channels of torrents discharging themselves into the Tuscan Sea.
Between this long chain, extending from Monte Antonio to Monte Incudine, and the tortuous ranges detached obliquely from it, lies a central area equal in surface to a fifth part of the whole island of which it forms the heart—the interior. The general inclination of this area, with the openings of the valleys, tends to the east. It does not form one single bason, but, intersected as it is in various directions by secondary ranges, and by mountains linking the principal chain, its contour is composed of a series of deep and generally narrow valleys, rising one above the other. The grandest as well as the most elevated of these basons is that of the Niolo, the citadel of Corsica.
These lofty mountain chains, with the numerous ramifications detached from them, and extending in all directions, render the communications between one place and another, between the coasts on opposite sides of the island, extremely difficult. The passage from the western to the eastern shore can only be effected by climbing to great elevations, through long and narrow gorges, through deep ravines of savage aspect, and covered with dense forests. The Corsicans give a lively idea of some of these toilsome paths by calling them scale,—ladders, staircases;—and such, indeed, they are, the steps, often prolonged for miles, being partly the work of Nature, partly cut in the rock by the hand of man.
GEOLOGY OF CORSICA.
In the present state of science there can be no difficulty in ascribing the origin of the three great lines of the Corsican mountains, to which all the others are subordinate, to three vast upheavings of the soil in the direction they take. The order of these elevations above the surface of the ancient sea thrice repeated in the long series of past ages, giving the first existence to the island, and by successive conglomerations shaping its present bold and irregular profile, may be also distinctly traced.
The masses first raised to the surface of the sea, supposed to be of igneous origin, lifted by the intense action of fire or subterranean heat from vast depths, and called by English geologists “Plutonic rocks,” as differing from “Volcanic,”—these masses constitute nearly the whole south-western coast of Corsica, one half of the whole island.
If an ideal line be drawn diagonally from a point so far north-west as Cape Revellata, near Calvi, to the point of Araso, far down the south-east coast near Porto Vecchio, this primary eruption may be traced in the several ranges, perpendicular to the ideal line and parallel with each other, which descending to the sea in the direction of from north-east to south-west, terminate in the principal promontories on the western coast, and form the numerous valleys which appear in succession from the Straits of Bonifacio to the Gulf of Porto.
Thus at the earliest epoch the principal axis of the island had its direction from the north-west to the south-east. The Capo Corso of those times lifted its head above the Sea of Calvi, and who can say how far the island extended at the opposite extremity? All we know is, that the group of rocky islets called the Isole Cerbicale, south-west of Porto Vecchio, with the Isola du Cavallo, and that Di Lavazzi off the coast at Bonifacio; and again, the islets Die Razzoli and Budelli on the opposite side of the Straits, with the larger islands of La Madaléna and Caprera, all of a similar formation with the primary Corsican range,—like detached fragments of some vast ruined structure,—appear to form the links of a chain which united Corsica with the mountain system of the north-eastern portion of the island of Sardinia.
These primitive masses are almost entirely granitic; and thus, at the epoch of its first emergence from the waters of the Mediterranean, no spark of animal or vegetable life existed in the new island.
So also one half of the masses raised by the second upheaval, having the same general direction, are granitic. But, as we advance towards the north-east, the granites insensibly resolve themselves into ophiolitic rocks,—a name given by French geologists to certain volcanic eruptions of the cretaceous era,—which are also found in the Morea.21 There are but few traces remaining of this second upheaval, which evidently laid in ruins great part of the northern extremity of the former one, cutting it at right angles to the east of the Gulf of Porto. This line, ranging from the south-west to the north-east into the heart of the Nebbio, is broken up and destroyed through nearly its whole length.
The disorder and ruin of these several points of the original system, and the almost total destruction of its northern part, were undoubtedly caused by the third and last upheaval which gave the island the form it presents at the present day. Its direction was from north to south, and so long as the mass then raised did not come in contact with the land created by former upheavals, it preserved its regular line, as we find in the mountain-chain of Capo Corso. But when, on emerging above the surface of the sea, this mass had to overcome at its southern extremity the resistance of the primary rocks upheaved long before, and now become hard and consolidated,—in that terrible shock, on the one hand, it changed, crushed, or ruined all that obstructed its progress, while, on the other, it varied its own direction and was itself broken up in many places, as appears from the openings of the valleys communicating from the interior with the plains of the eastern littoral and giving a passage to the torrents which fall into the sea on this coast,—the Bevinco, the Golo, the Tavignano, the Fiumorbo.
The fundamental rocks brought up by this third and last upheaval are ophiolitic, and metamorphic, or primary, limestone, overlaid in some places by secondary formations. “The granites on the west, as well as the south, of the island include some beds of gneiss and schistes at their extremities.”—(Gueymard). Almost everywhere the granite is covered—an evident proof that the epoch of its eruption preceded that when the deposits were formed in the depths of the sea, and deposited in horizontal strata on the crystalline masses of the granite.
Masses of euritic and porphyritic rocks intersect the granites, and a distinct formation of porphyries crowns Monte Cinto, Vagliorba, and Pertusato, the highest summits of the Niolo, covering the granite. These porphyries are pierced by greenstone two or three feet thick, and the granites are intersected by numerous veins of amphibolite (hornblende) and greenstone, generally running from east to west.
Transition rocks, as they are called, occupy the whole of Capo Corso and the east of the island. They consist of talcose-schiste, bluish-grey limestone, talc in beds, serpentine, black marble similar to the oldest in the Alps, quartz, feldspar, and porphyries.
The tertiary strata are only found at certain points in isolated fragments. One of these occupies the bottom of the Gulf of San Fiorenzo and part of its eastern shore. There the beds rest with a strong inclination against the lower declivities of the chain of Capo Corso, rising from upwards of 600 to 900 feet above the level of the Mediterranean,—a distinct proof that their formation at the bottom of the sea was anterior to the upheaval of that chain, and of the whole system of mountains having their direction north and south.
In the deep escarped valleys between San Fiorenzo and the tower of Farinole, the tertiary deposits are seen in successive layers forming beds which in some places are in the aggregate from 400 to 500 feet thick, and the calcareous beds contain great quantities of fossil remains of marine animals of low organisation, such as sea-urchins, pectens, and other shells; forming a compact mass, of which the greater part of the formation consists. The singular phenomenon of the presence of rounded boulders of euritic porphyry, resembling that of the Niolo, embedded in these strata, proves to a certainty that at an epoch anterior to the upheaval of the system running north and south, and of the mountains of La Tenda depending on it, the high valleys of the present bason of the Golo, and especially that of the Golo, were prolonged to the sea.
A second tertiary deposit exists near Volpajola, on the left bank of the Golo, nearly eight miles from the eastern coast. The beds lying horizontally are full of shells.
We find a third fragment of a tertiary formation on the part of the littorale stretching from the mouth of the Alistro to that of the Fiumorbo, in the middle of which stood the ancient city of Aleria. In some places these beds have been lifted without any sensible alteration of their original form of deposit in horizontal strata, and throughout they bear a close resemblance to the tertiary formation of San Fiorenzo.
A fourth, and more striking, example of the same formation is exhibited at the southern extremity of the island. There we find an horizontal plateau from 200 to 300 feet high between the Gulf of Sta-Manza and Bonifacio. The promontory on which that town and fortress stands, and the whole adjoining coast along the straits, present exactly the same appearances as the white chalk cliffs of Dover; and at the Cala di Canetta these calcareous rocks rise à pic over the sea 150 and 200 feet. There is a perfect analogy between this formation and those of San Fiorenzo and the Fiumorbo already mentioned. Only, this last contains a much greater variety of fossil remains, both animal and vegetable, consisting of lignites, oyster-shells, large pectens, operculites, and fragments of sea-urchins, polypi, &c. We shall have an opportunity of mentioning hereafter the curious caverns worn in the soft calcareous rock by the force of the waves lashing this coast with so much violence in the storms to which the Straits of Bonifacio are exposed.
Coming now to the alluvial deposits, we find them extending over the great plains on the eastern coast of the island, the littorale mentioned in an early chapter of this work. The plain of Biguglia, for instance, was formed by one of those vast inundations which have received the name of diluvial currents, and swept away a great number of species of animals. In fact, we find traces of one of these inundations in a breccia formed of the fossil bones of animals in the hills near Bastia. Among these fossil bones Cuvier has remarked the head of a lagomys, a little hare without any tail,—a species still existing in Siberia.22 It would too much lengthen these remarks were we to enter on an inquiry into the age and character of these osseous breccia, but the curious reader is referred to Lyell’s “Elements”23 for some interesting observations on fossil mammalia found in alluvial deposits alternating with breccia. We are not aware, however, that the hills near Bastia are connected with volcanic action as those of Auvergne, to which Mr. Lyell refers.
Indeed, in concluding this notice of Corsican geology, we have only to remark that, although Corsica has no existing volcanoes, it would appear, from fragments preserved in the cabinets of Natural History, that, here and there, a few rare traces of extinct volcanoes of very ancient date have been discovered, in the neighbourhood of Porto Vecchio, Aleria, Cape Balistro, in the Gulf of Sta Manza, and some other places.