Man and Nature Part 40

[435] American observers do not agree in their descriptions of the form and character of the sand grains which compose the interior dunes of the North American desert. C. C. Parry, geologist to the Mexican Boundary Commission, in describing the dunes near the station at a spring thirty-two miles west from the Rio Grande at El Paso, says: "The separate grains of the sand composing the sand hills are seen under a lens to be angular, and not rounded, as would be the case in regular beach deposits."--_U. S. Mexican Boundary Survey, Report of_, vol. i, _Geological Report of C. C. Parry_, p. 10.

In the general description of the country traversed, same volume, p. 47, Colonel Emory says that on an "examination of the sand with a microscope of sufficient power," the grains are seen to be angular, not rounded by rolling in water.

On the other hand, Blake, in _Geological Report, Pacific Railroad Rep._, vol. v, p. 119, observes that the grains of the dune sand, consisting of quartz, chalcedony, carnelian, agate, rose quartz, and probably chrysolite, were much rounded; and on page 241, he says that many of the sand grains of the Colorado desert are perfect spheres.

On page 20 of a report in vol. ii of the _Pacific Railroad Report_, by the same observer, it is said that an examination of dune sands brought from the Llano Estacado by Captain Pope, showed the grains to be "much rounded by attrition."

The sands described by Mr. Parry and Colonel Emory are not from the same localities as those examined by Mr. Blake, and the difference in their character may denote a difference of origin or of age.

[436] LAURENT (_Memoire sur le Sahara_, pp. 11, 12, and elsewhere) speaks of a funnel-shaped depression at a high point in the dunes, as a characteristic feature of the sand hills of the Algerian desert. This seems to be an approximation to the crescent form noticed by Meyen and Poppig in the inland dunes of Peru.

[437] _Travels in Peru_, New York, 1848, chap. ix.

[438] Notwithstanding the general tendency of isolated coast dunes and of the peaks of the sand ridges to a.s.sume a conical form, Andresen states that the hills of the inner or landward rows are sometimes _bow-shaped_, and sometimes undulating in outline.--_Om Klitformationen_, p. 84. He says further that: "Before an obstruction, two or three feet high and considerably longer, lying perpendicularly to the direction of the wind, the sand is deposited with a windward angle of from 6 to 12, and the bank presents a concave face to the wind, while, behind the obstruction, the outline is convex;" and he lays it down as a general rule, that a slope, _from_ which sand is blown, is left with a concavity of about one inch of depth to four feet of distance; a slope, _upon_ which sand is dropped by the wind, is convex.

It appears from Andresen's figures, however, that the concavity and convexity referred to, apply, not to the _horizontal longitudinal_ section of the sand bank, as his language unexplained by the drawings might be supposed to mean, but to the _vertical cross-section_, and hence the dunes he describes, with the exception above noted, do not correspond to those of the American deserts.--_Om Klitformationen_, p.

86.

The dunes of Gascony, which sometimes exceed three hundred feet in height, present the same concavity and convexity of _vertical_ cross-section. The slopes of these dunes are much steeper than those of the Netherlands and the Danish coast; for while all observers agree in a.s.signing to the seaward and landward faces of those latter, respectively, angles of from 5 to 12, and 30 with the horizon, the corresponding faces of the dunes of Gascony present angles of from 10 to 25, and 50 to 60.--LAVAL, _Memoire sur les Dunes de Gascogne, Annales des Ponts et Chaussees_, 1847, 2me semestre.

[439] Krause, speaking of the dunes on the coast of Prussia, says: "Their origin belongs to three different periods, in which important changes in the relative level of sea and land have unquestionably taken place. * * * Except in the deep depressions between them, the dunes are everywhere sprinkled, to a considerable height, with brown oxydulated iron, which has penetrated into the sand to the depth of from three to eighteen inches, and colored it red. * * * Above the iron is a stratum of sand differing in composition from ordinary sea sand, and on this, growing woods are always found. * * * The gradually acc.u.mulated forest soil occurs in beds of from one to three feet thick, and changes, proceeding upward, from gray sand to black humus." Even on the third or seaward range, the sand gra.s.ses appear and thrive luxuriantly, at least on the west coast, though. Krause doubts whether the dunes of the east coast were ever thus protected.--_Der Dunenbau_, pp. 8, 11.

[440] LAVAL, _Memoire sur les Dunes de Gascogne, Annales des Ponts et Chaussees_, 1847, 2me semestre, p. 231. The same opinion had been expressed by BReMONTIER, _Annales des Ponts et Chaussees_, 1833, 1er semestre, p. 185.

[441] "In the Middle Ages," says Willibald Alexis, as quoted by Muller, _Das Buch der Pflanzenwelt_ i, p. 16, "the Nehrung was extending itself further, and the narrow opening near Lochstadt had filled itself up with sand. A great pine forest bound with its roots the dune sand and the heath uninterruptedly from Danzig to Pillau. King Frederick William I was once in want of money. A certain Herr von Korff promised to procure it for him, without loan or taxes, if he could be allowed to remove something quite useless. He thinned out the forests of Prussia, which then, indeed, possessed little pecuniary value; but he felled the entire woods of the Frische Nehrung, so far as they lay within the Prussian territory. The financial operation was a success. The king had money, but in the elementary operation which resulted from it, the state received irreparable injury. The sea winds rush over the bared hills; the Frische Haff is half-choked with sand; the channel between Elbing, the sea, and Konigsberg is endangered, and the fisheries in the Haff injured. The operation of Herr von Korff brought the king 200,000 thalers. The state would now willingly expend millions to restore the forests again."

[442] STARING, _Voormaals en Thans_, p. 231. Had the dunes of the Netherlandish and French coasts, at the period of the Roman invasion, resembled the moving sand hills of the present day, it is inconceivable that they could have escaped the notice of so acute a physical geographer as Strabo; and the absolute silence of Caesar, Ptolemy, and the encyclopaedic Pliny, respecting them, would be not less inexplicable.

The Old Northern language, the ancient tongue of Denmark, though rich in terms descriptive of natural scenery, had no name for dune, nor do I think the sand hills of the coast are anywhere noticed in Icelandic literature. The modern Icelanders, in treating of the dunes of Jutland, call them _klettr_, hill, cliff, and the Danish _klit_ is from that source. The word Dune is also of recent introduction into German. Had the dunes been distinguished from other hillocks, in ancient times, by so remarkable a feature as the propensity to drift, they would certainly have acquired a specific name in both Old Northern and German. So long as they were wooded knolls, they needed no peculiar name; when they became formidable, from the destruction of the woods which confined them, they acquired a designation.

[443] The sands of Cape Cod were partially, if not completely, covered with vegetation by nature. Dr. Dwight, describing the dunes as they were in 1800, says: "Some of them are covered with beach gra.s.s; some fringed with whortleberry bushes; and some tufted with a small and singular growth of oaks. * * * The parts of this barrier, which are covered with whortleberry bushes and with oaks, have been either not at all, or very little blown. The oaks, particularly, appear to be the continuation of the forests originally formed on this spot. * * * They wore all the marks of extreme age; were, in some instances, already decayed, and in others decaying; were h.o.a.ry with moss, and were deformed by branches, broken and wasted, not by violence, but by time."--_Travels_, iii, p.

91.

[444] Bergsoe (_Reventlovs Virksomhed_, ii, 3) states that the dunes on the west coast of Jutland were stationary before the destruction of the forests to the east of them. The felling of the tall trees removed the resistance to the lower currents of the westerly winds, and the sands have since buried a great extent of fertile soil. See also same work, ii, p. 124.

[445] "We must, therefore, not be surprised to see the people here deal as gingerly with their dunes, as if treading among eggs. He who is lucky enough to own a molehill of dune pets it affectionately, and spends his substance in cheris.h.i.+ng and fattening it. That fair, fertile, rich province, the peninsula of Eiderstadt in the south of Friesland, has, on the point toward the sea, only a tiny row of dunes, some six miles long or so; but the people talk of their fringe of sand hills as if it were a border set with pearls. They look upon it as their best defence against Neptune. They have connected it with their system of dikes, and for years have kept sentries posted to protect it against wanton injury."--J. G. KOHL, _Die Inseln u. Marschen Schleswig-Holsteins_, ii, p. 115.

[446] Sand banks sometimes connect themselves with the coast at both ends, and thus cut off a portion of the sea. In this case, as well as when salt water is enclosed by sea dikes, the water thus separated from the ocean gradually becomes fresh, or at least brackish. The Haffs, or large expanses of fresh water in Eastern Prussia--which are divided from the Baltic by narrow sand banks called Nehrungen, or, at sheltered points of the coast, by fluviatile deposits called Werders--all have one or more open pa.s.sages, through which the water of the rivers that supply them at last finds its way to the sea.

[447] ANDRESEN, _Om Klitformationen_, pp. 68-72.

[448] Id., pp. 231, 232. Andresen's work, though printed in 1861, was finished in 1859. Lyell (_Antiquity of Man_, 1863, p. 14) says: "Even in the course of the present century, the salt waters have made one eruption into the Baltic by the Liimfjord, although they have been now again excluded."

[449] FORCHHAMMER, _Geognostische Studien am Meeres-Ufer_. LEONHARD und BRONN, _Jahrbuch_, 1841, pp. 11, 13.

[450] ANDRESEN, _Om Klitformationen_, pp. 68, 72.

[451] _Voormaals en Thans_, pp. 126, 170.

[452] See a very interesting article ent.i.tled "Le Littoral de la France," by eLISeE RECLUS, in the _Revue des Deux Mondes_, for December, 1862, pp. 901, 936.

[453] _De Bodem van Nederland_, i, p. 425. See _Appendix_, No. 60.

[454] The movement of the dunes has been hardly less destructive on the north side of the Gironde. Sea the valuable article of eLISeE RECLUS already referred to, in the _Revue des Deux Mondes_, for December, 1862, ent.i.tled "Le Littoral de la France."

[455] LAVAL, _Memoire sur les Dunes du Golfe de Gascogne, Annales des Ponts et Chaussees_, 1847, p. 223. The author adds, as a curious and unexplained fact, that some of these pools, though evidently not original formations but mere acc.u.mulations of water dammed up by the dunes, have, along their western sh.o.r.e, near the base of the sand hills, a depth of more than one hundred and thirty feet, and hence their bottoms are not less than eighty feet below the level of the lowest tides. Their western banks descend steeply, conforming nearly to the slope of the dunes, while on the northeast and south the inclination of their beds is very gradual. The greatest depth of these pools corresponds to that of the sea ten miles from the sh.o.r.e. Is it possible that the weight of the sands has pressed together the soil on which they rest, and thus occasioned a subsidence of the surface extending beyond their base? See _Appendix_, No. 61.

[456] ANDRESEN, _Om Klitformationem_, pp. 56, 79, 82.

[457] STARING, _De Bodem van Nederland_, i, pp. 329-331. Id., _Voormaals en Thans_, p. 163. ANDRESEN, _Om Klitformationen_, pp. 280, 295.

The creation of new dunes, by the processes mentioned in the text, seems to be much older in Europe than the adoption of measures for securing them by planting. Dr. Dwight mentions a case in Ma.s.sachusetts, where a beach was restored, and new dunes formed, by planting beach gra.s.s.

"Within the memory of my informant, the sea broke over the beach which connects Truro with Province Town, and swept the body of it away for some distance. The beach gra.s.s was immediately planted on the spot; in consequence of which the beach was again raised to a sufficient height, and in various places into hills."--_Dwight's Travels_, iii, p. 93.

[458] STARING, i, pp. 310, 332.

[459] There is some confusion in the popular use of these names, and in the scientific designations of sand plants, and they are possibly applied to different plants in different places. Some writers style the gourbet _Calamagrostis arenaria_, and distinguish it from the Danish Klittetag or Hjelme.

[460] Bread, not indeed very palatable, has been made of the seeds of the arundo, but the quant.i.ty which can be gathered is not sufficient to form an important economical resource.----ANDRESEN, _Om Klitformationen_, p. 160.

[461] BERGSoE, _Reventlovs Virksomhed_, ii, p. 4.

[462] Measures were taken for the protection of the dunes of Cape Cod, in Ma.s.sachusetts, during the colonial period, though I believe they are now substantially abandoned. A hundred years ago, before the valley of the Mississippi, or even the rich plains of Central and Western New York, were opened to the white settler, the value of land was relatively much greater in New England than it is at present, and consequently some rural improvements were then worth making, which would not now yield sufficient returns to tempt the investment of capital. The money and the time required to subdue and render productive twenty acres of sea sand on Cape Cod, would buy a "section" and rear a family in Illinois. The son of the Pilgrims, therefore, abandons the sand hills, and seeks a better fortune on the fertile prairies of the West.

Dr. Dwight, who visited Cape Cod in the year 1800, after describing the "beach gra.s.s, a vegetable bearing a general resemblance to sedge, but of a light bluish-green, and of a coa.r.s.e appearance," which "flourishes with a strong and rapid vegetation on the sands," observes that he received "from a Mr. Collins, formerly of Truro, the following information:" "When he lived at Truro, the inhabitants were, under the authority of law, regularly warned in the month of April, yearly, to plant beach gra.s.s, as, in other towns of New England, they are warned to repair highways. It was required by the laws of the State, and under the proper penalties for disobedience; being as regular a public tax as any other. The people, therefore, generally attended and performed the labor. The gra.s.s was dug in bunches, as it naturally grows; and each bunch divided into a number of smaller ones. These were set out in the sand at distances of three feet. After one row was set, others were placed behind it in such a manner as to shut up the interstices; or, as a carpenter would say, so as to break the joints. * * * When it is once set, it grows and spreads with rapidity. * * * The seeds are so heavy that they bend down the heads of the gra.s.s; and when ripe, drop directly down by its side, where they immediately vegetate. Thus in a short time the ground is covered.

"Where this covering is found, none of the sand is blown. On the contrary, it is acc.u.mulated and raised continually as snow gathers and rises among bushes, or branches of trees cut and spread upon the earth.

Nor does the gra.s.s merely defend the surface on which it is planted; but rises, as that rises by new acc.u.mulations; and always overtops the sand, however high that may be raised by the wind."--_Dwight's Travels in New England and New York_, ii, p. 92, 93.

This information was received in 1800, and it relates to a former state of things, probably more than twenty years previous, and earlier than 1779, when the Government of Denmark first seriously attempted the conquest of the dunes.

The depasturing of the beach gra.s.s--a plant allied in habits, if not in botanical character, to the arundo--has been attended with very injurious effects in Ma.s.sachusetts. Dr. Dwight, after referring to the laws for its propagation, already cited, says: "The benefit of this useful plant, and of these prudent regulations, is, however, in some measure lost. There are in Province Town, as I was informed, one hundred and forty cows. These animals, being stinted in their means of subsistence, are permitted to wander, at times, in search of food. In every such case, they make depredations on the beach gra.s.s, and prevent its seeds from being formed. In this manner the plant is ultimately destroyed."--_Travels_, iii, p. 94.

On page 101 of the same volume, the author mentions an instance of great injury from this cause. "Here, about one thousand acres were entirely blown away to the depth, in many places, of ten feet. * * * Not a green thing was visible except the whortleberries, which tufted a few lonely hillocks rising to the height of the original surface and prevented by this defence from being blown away also. These, although they varied the prospect, added to the gloom by their strongly picturesque appearance, by marking exactly the original level of the plain, and by showing us in this manner the immensity of the ma.s.s which had been thus carried away by the wind. The beach gra.s.s had been planted here, and the ground had been formerly enclosed; but the gates had been left open, and the cattle had destroyed this invaluable plant."

[463] ANDRESEN, _Om Klitformationen_, pp. 237, 240.

[464] "These plantations, perseveringly continued from the time of Bremontier now cover more than 40,000 hectares, and compose forests which are not only the salvation of the department, but const.i.tute its wealth."--CLAVe, _etudes Forestieres_, p. 254.

Other authors have stated the plantations of the French dunes to be much more extensive.

[465] KRUSE, _Dunenbau_, pp. 34, 38, 40.

[466] These processes are substantially similar to those employed in the pineries of the Carolinas, but they are better systematized and more economically conducted in France. In the latter country, all the products of the pine, even to the cones, find a remunerating market, while, in America, the price of resin is so low, that in the fierce steamboat races on the great rivers, large quant.i.ties of it are thrown into the furnaces to increase the intensity of the fires. In a carefully prepared article on the Southern pineries published in an American magazine--I think Harper's--a few years ago, it was stated that the resin from the turpentine distilleries was sometimes allowed to run to waste; and the writer, in one instance, observed a ma.s.s, thus rejected as rubbish, which was estimated to amount to two thousand barrels. See _Appendix_, No. 62.

[467] ANDRESEN, _Om Klitformationen_, pp. 78, 262, 275.

[468] LAVAL, _Memoire sur les Dunes du Golfe de Gascogne, Annales des Ponts et Chaussees_, 1847, 2me semestre, p. 261. See _Appendix_, No.

63.