put up again, and in the second set higher. Goury thus describes how this raising is effected. The top of each plank is gripped by pincers with a long handle. A lever is passed through the ring of the handle and the plank is thus raised. The soil is then pressed down with the feet. Or the plank is bound round with a cord or chain through which a lever is passed. One end of the lever rests on the next plank and the [free] end is raised. At all the works the setting-up of blown-down palisades and the raising of buried ones is paid for at the rate of, in the first case, 5 c. or 6 c.; in the other 10 c. These prices apply to the linear metre of palisade set up or raised. The amount of this setting-up and raising has varied greatly. At the Biscarrosse works, the plan of which provides for 7,430 metres of palisades, comprising 3,415 metres along the sea, particularly exposed, it was foreseen that 20,000 metres of setting-up and 100,000 metres of raising would be required-that is an average of about three settings-up and thirteen raisings [per metre]. In fact, only 6,600 metres of settings-up and 47,000 metres of raisings have been done. The planks of the palisades were 1.80 m. long; others at the less exposed parts were 1:35 m. only. The palisades were paid for, including material, at 1 franc to 2 francs the linear metre, according to the works, a cost which was much affected by transport. CLAYONNAGES AND CORDONS. "The clayonnages are single or double [in height]: the first consist of a row of stakes 2-4 in. in mean diameter and 4 ft. 9 in. long, spaced 19 in. from centre to centre; they are driven 19 in. into the sand, and interwoven to the height of 3 ft. 3 in. above the ground. "For double [in height] clayonnages the stakes are to be 8 ft. 2 in. long and 31 in. mean diameter; but the interlacing with branches at first is done to a height of only 3 ft. 3 in. above the ground, so as to leave an equal height for a second interlacing when the first becomes crowned' [with sand]. "The cordons of defence are to be formed of bundles of brushwood chosen 7 in. in diameter at the base and 273 in. at least in height, planted in quincunx in two or three rows, according to circumstances, and driven 11 in. into the sand." Cost per linear metre at this works: Single clayonnages, 1d.; double, 1d. At this same Lacanau works double clayonnages are planned instead of palisades at the boundaries of dunes which are little exposed to sanddrift; in other places, according to the plan. 66 Single clayonnages interwoven for a height of only 1 ft. 7 in. are to be constructed at the foot of the dunes at all points where the flats, at the time the planting is done, are sandy enough to cause encroachments." THE LITTORAL DUNE. We have seen that the Biscarrosse works stretch right to the beach, and that they had to be protected against the encroachment of sand by a palisade 3,735 yards long, the length of that side of the works. The accumulation of a great volume of sand has thus been produced which *Clayonnage might be translated by "brushwood fence." has built up a veritable dune-the littoral dune. In conformity with the plan clayonnages parallel to the palisade have been established. The design and the manner of proceeding are not indicated in the plan for this clayonnage, but they are explained in the works that I have cited of Grandjean and Bert. That Inspector and that Administrator of Forests were so much the better acquainted with it that the Forest Service was led to apply to the littoral dune all along the coast such considerable repairs as were equivalent to a reconstruction. In order that this dune may not be damaged by the winds it is necessary that it should not exceed a certain height without being widened at the summit. In this design, on the dune APB (fig. 8), according to Grandjean, they have erected at 2 metres to the west of the palisade P a clayonnage C. Between these two defences bunches of brushwood were planted. The sand accumulates and the dune takes the outline DCPB. The palisade is then raised to P', the clayonnage (C) is heightened by a second clayonnage (C'), and the intervening platform is consolidated by new bunches of brushwood; the result is a new outline IC'P'H. And these operations are repeated till the desired height is realized. Often they prepare a good width and a gentle slope in establishing, even at the beginning of the formation of a dune, a clayonnage (C), but placed at a greater distance from the palisade P, and (during this commencing period) without bunches of brushwood in the intervening space: this is probably the clayonnage of the Biscarrosse works. The littoral dune is fixed with marram-grass by means of a plantation, or, failing plants, by sowing seed under covering at the rate of 33 lb. of seed per 2 acres. Grandjean considers that in order that it may suffer the least damage the littoral dune should not be made more than 323 ft. in height, and its slope towards the coast should be made gradual by means of brushwood to an inclination of 26 to 27 in the 100, but not more gradual. If a breach is made by the wind in a littoral dune, it is checked and repaired by one or several cordons planted with plenty of marramgrass; or, indeed, the bottom of the breach is stocked with tufts of brushwood planted vertically. If in the course of time the wind forms a lump (called a truc) the marram-grass [on it] is pulled up and the surface loosened with a mattock, and the wind is not long in carrying it away. Irregularities [of surface] greatly favour attack by the wind. In actual fact the littoral dune, when fully brought into a state of repair, has neither a palisade nor bunches of brushwood. It has only the clayonnage, as c, almost level with the ground, to mark the arrest. This dune is enormously widened towards the east. DIVERSE CONDITIONS. The plan of the Lacanau works stipulates : "The contractor is responsible for success until three years after the last sowings have germinated. The annual examination is declared favourable to the contractor when the seeds have sprouted-during the first year, fifteen stalks of pine, and the same of broom, per square metre; the second year, ten stalks of each species; the third year, six stalks of each species. The surfaces of sown areas are measured horizontally, without taking into account the inclination of the slopes." Documents on other files show that it is dangerous to suspend work for long: the sown area becomes buried in sand, the covering blown away, first from the borders, and later progressively from more of the surface. It is necessary, as Deschamps junior pointed out in 1833, to mark out the limits of the covering north and south according to the same principle as with palisades. It is also sometimes necessary to defend them by cordons. All damage should be repaired at once and palisades erected [where necessary]. Works abandoned in consequence of the calamitous political troubles in 1813 suffered great damage. It is very important to prevent stock from pasturing [on the dunes]. Le Boullenger, in his report of 1817, even asserts, with some exaggeration, "It is probable that if the dunes were left to themselves, and not covered with numerous cattle which shave off and tear out all plant-life which grows there, the vegetation would soon get the upper hand, and overcome by degrees all the moving sands. The passage of stock alters the dunes in this way their steps break down the demi-aggregation which binds the particles of sand and make it mobile to the force of the winds. Thus the dunes over which cattle daily pass become through that alone a depression, and soon a valley.' In 1823 Saint-Aubin justly expressed the opinion that but for the cattle many dunes would be fixed naturally, and nothing more would have to be done than to plant them with a shovel to get them covered with forest." Since the commencement of fixation the wandering of cattle has been forbidden in sown areas and in their proximity, and likewise upon dunes that it is proposed to fix in a few years, and on flats destined to furnish covering-material. It is largely a question of cows and horses living in little groups in a wild state, and belonging to nobody. The rangers have orders to shoot these horses with their rifles. Even in 1839 a ranger of the Porge complains of "the havoc wrought by the wild horses this winter." A crop of young pines, protected by thick brushwood, is very favourable to fires, but nevertheless outbreaks of fire have been very few during the fixation of the dunes. This is because, the country being uninhabited (because unproductive), there is almost no one who, wilfully or not, could start a fire. I have turned up in the files accounts of certain fires which were lighted by shepherds desiring to revenge themselves for prosecution for pasturing their flocks in sown grounds; accounts of other fires due to the carelessness of hunters; of others arising from the spread of fires kindled annually in the moor, east of the dunes, to renew the grass. All these causes have been made the object of regulations for their suppression or decrease. I add by way of an historical curiosity that on the 11th April, 1814, at the close of the war, an English troop of seven sailors * In 1848 Conte-Grandchamps [considered that he] saw in that a way to excavate roads across the dunes of Mimizan without incurring any expense. came to Verdon to destroy by fire the dwelling of the chief of works and the cottage and stables of the contractor without any one knowing the reason. RECKONING OF THE EXPENSE. It appears to me that it would be interesting to close this examination of operations in detail by a reckoning of the expenses of the two works that I have taken throughout as examples. I have found only the expenses made in the contract. I am unaware as to what they have been (though certainly small) during administration. LACANAU WORKS. Reckoning of Work done by the Contractor, dated 24th November, 1859. 340 hect. 53 ares sown in pine, broom, and marram-grass seed, at 15 fr. 60 c. per hectare 86 hect. 18 ares 5 cent. sown with seed of marram-grass only, at 3 fr. 40 c. per hectare 340 hect. 53 ares fixation with full covering, at 96 fr. 60 c. per hectare 93 hect. 25 ares 60 cent. fixation with halfcovering, at 49 fr. 60 c. per hectare C. Fr. C. Fr. 5,312 27 32,895 293 3 20 4,625 50 Total ... Deduct discount on contract at 3 per cent.... Cost in toto of work done It is therefore seen that the protective works have cost relatively little -about a seventy-fifth. BISCARROSSE WORKS. Reckoning of Work done by the Contractor, dated 15th October. 1860. The price of 164 francs the hectare sown is an average price, applicable to the whole works. The contract gave the enormous rebate of 33 per cent. 9,219.85 m. clayonnages on stakes 2.50 m. long, at 30 c. per linear metre This reckoning does not include a part of the palisades constructed of old boards taken from the defences of other works which had become useless by the juxtaposition of new works. 645 hect. 10 ares 90 cent. sown and covered, at 164 fr. per hectare ... 62 hect. 51 ares 26 cent., plantation of marram-grass, at 92 fr. per hectare Fr. 105,797 88 C. ... 5,751 16 2,765 95 12,263 metres clayonnages on stakes 150 m., at 25 c. per linear metre 3,065 75 5,828 metres new palisades (planks 1.80 m.), at 2 fr. per linear metre .... 9,668 raising of clayonnages by interweaving branches on 6,586 metres setting up blown-down palisades, at 5 c. per 273 metres new lower palisades (planks 1.35 m.), at 1 fr. Total Deduct discount of 33 per cent.... Sum total It follows from this reckoning that out of 135,997 francs of total cost, discount (rebate) included, the defences (palisades, clayonnages) cost 24,448 francs, not counting the palisades made of old planks used again. This is almost a fifth, which is a considerable proportion, although the explanations that I have given made it to be expected. VARIOUS QUESTIONS. ECONOMIC YIELD. The authors of the fixation of the Gascony dunes considered, although as a secondary matter, the pecuniary advantage of transforming these sterile regions into productive territory. At present, thanks to them, these sands, formerly bare, are covered with magnificent pine forests which produce resin and timber in abundance. Do the receipts from these operations cover the cost? Omitting those dunes and flats that have been restored to their ancient owners or alienated, the State now possesses 47,000 hectares (21,000 in Gironde and 26,000 in Landes), including in that area the littoral zone, which is not wooded and is unproductive. During the last four years (1910-13) this area has produced in timber, resin, &c., a return, varying but little, which on an average is something over 2,100,000 francs. On the other hand, the expenses of administrationthe chief items being, of course, the work done and the wages of staffare slightly above 300,000 francs per year. The net receipts are therefore 1,800,000 francs from 47,000 hectares-that is to say, on an average, 38 francs per hectare. |