1902 Encyclopedia > Jura


JURA. This range may be roughly described as the block of mountains rising between the Rhine and the Rhone, and forming the frontier between France and Switzerland. The gorges by which these two rivers force their way to the plains cut off the Jura from the Swabian and Franconian ranges to the north and those of Dauphine to the south. But in very early days, before these gorges had been carved out, there were no openings in the Jura at all, and even now its three chief rivers—the Doubs, the Loue, and the Ain—flow down the western slope, which is both much longer and but half as steep as the eastern. Some geographers extend the name Jura to the Swabian and Franconian ranges between the Danube and the Neckar and the Main; but, though these are similar in point of composition and direction to the range to the south, it is most convenient to limit the name to the mountain ridges lying between France and Switzer-land, and this narrower sense will be adopted here.
The Jura has been aptly described as a huge plateau about 156 miles long and 38 miles broad, hewn into an oblong shape, and raised by internal forces to an average height of from 1950 to 2600 feet above the surrounding plains. The shock by which it was raised, and the vibra-tion caused by the elevation of the great chain of the Alps, produced many transverse gorges or "cluses," while on the plateaus between these subaerial agencies have exer-cised their ordinary influence.

Geologically, the sedimentary rocks of the Jura belong to the Mesozoic age, and were deposited in a sea of variable depth, traces of which survive in the vast salt mines from which Salins and Lons-le-Saunier derive their names. The special name of these fossiliferous strata is Oolitic; they are also called Jurassic, from the fact that the Jura is entirely made up of such layers. They include sands, sandstones, marls, clays, and limestones ; and the water that deposited these strata must have been highly charged with carbonate of lime, since calcareous rocks abound in the Jura. The action on these rocks of the carbonic acid gas discharged by all animals has been to transform them into bicarbonate of lime, a very soluble body, and hence the work of erosion has been much facilitated. The countless blocks of gneiss, granite, and other crystalline formations which are found in such numbers on the slopes of the Jura, and go by the name of " erratic blocks " (of which the best known instance—the Pierre à Bot—is 40 feet in diameter, and rests on the side of a hill 900 feet above the Lake of Neuchâtel), have been transported thither from the Alps by ancient glaciers, which have left their mark on the Jura range itself in the shape of striations and moraines.

The general direction of the chain is from north-east to south-west, but a careful study reveals the fact that there were in reality two main lines of upheaval, viz., north to south and east to west, the former best seen in the southern part of the range and the latter in the northern ; and it was by the union of these two forces that the lines north-east to south-west (seen in the greater part of the chain), and north-west to south-east (seen in the Villebois range at the south-west extremity of the chain), were produced. This is best realized if we take Besançon as a centre ; to the north the ridges run east and west ; to the south, north and south, while to the east the direction is north-east to south-west.
Before considering the topography of the interior of the Jura, it may be convenient to take a brief survey of its outer slopes.

1. The northern face dominates on one side the famous "Trouée" (or Trench) of Belfort, one of the great geographical centres of Europe, whence routes run north down the Rhine to the North Sea, south-east to the Danube basin and Black Sea, and south-west into France and so to the Mediterranean basin. It is now so strongly fortified that it becomes a question of great strategical im-portance to prevent its being turned by means of the great central plateau of the Jura, which, as we shall see, is a network of roads and railways. On the other side it overhangs the ' ' Trouée " of the Black Forest towns on the Rhine (Rheinfelden, Sackingen, Laufenhurg, and Waldshut) through which the central plain of Switzerland is easily gained. On this north slope two openings offer routes into the interior of the chain,—the valley of the Doubs belonging to France, and the valley of the Birs belonging to Swit-zerland. Belfort is the military, Mühlhausen the industrial, and Basel the commercial centre of this slope.

2. The eastern and western faces offer many striking parallels. The plains through which flow the Aar and the Saône have each been the bed of an ancient lake, traces of which remain in the lakes of Neuchâtel, Bienne, and Morat. The west face runs mainly north and south like its great river, and for a similar reason the east face runs north-east to south-west. Again, both slopes are pierced by many transverse gorges or "cluses" (due to fracture and not to erosion), by wdiich access is gained to the great central plateau of Pontarlier, though these are seen more plainly on the east face than on the west; thus the gorges at the exit from which Lons le Saunier, Poligny, Arbois, and Salins are built balance those of the Suze, of the Val de Ruz, of the Val de Travers, and of the Val d'Orbe, though on the east face there is but one city which commands al1 these important routes—Neuchâtel. This town is thus marked out by nature as a great military and industrial centre, just as Besançon on the west, which has besides to defend the route from Belfort down the Doubs. These easy means of communicating with the Free County of Burgundy or Franche Comté accounts for the fact that the dialect of Neuchâtel is Burgundian, and that it was held generally by Burgundian nobles, though most of the country near it was in the hands of the house of Savoy until gradually annexed by Bern. The Ohasseron (5286 feet) is the central point of the eastern face, commanding the two great railways which join Neu-châtel and Pontarlier. It is in a certain sense parallel to the valley of the Loue on the west face, which flows into the Doubs a little to the south of Dole, the only important town of the central portion of the Saône basin. South of the Val d'Orbe the east face becomes a rocky wall crowned by all the highest summits of the chain—the Mont Tendre (5512 feet), the Dale (5507 feet), the Reculet (5643 feet), the Crêi de la Neige (5653 feet), and the Grand Credo (5276

feet), the uniformity of level being as striking as on the west edge of the Jura, though there the absolute height is far less. The posi-tion of the Dole is similar to that of the Chasseron, as along the sides of it run the great roads of the Col do St Cergues (4159 feet) and the Col de la Faucille (4341 feet), the latter leading through the Vallée des Dappes, which was divided in 1862 between France and Switzerland, after many negotiations. The height of these roads shows that they are passages across the chain, rather than through natural depressions.

3. The southern face is supported by two great pillars—on the east by the Grand Credo and on the west by the ridge of Revermont (2529 feet) above Bourg en Bresse ; between these a huge bastion I : he district of Bugey) stretches away to the south, forcing the Rhone to make a long détour. On the two sides of this bastion the plains in which Amberieu and Culoz stand balance one another, and are the meeting points of the routes which cut through the bastion by means of deep gorges. On the eastern side this great wedge is ! steep and rugged, ending in the Grand Colombier (5033 feet) above • Culoz, and it sinks on the western side to the valley of the Ain, the district of Bresse, and the plateau of Dombes. The junction of the Ain and the Suraud at Pont d'Ain on the west balances that of the Valserine and the Rhone at Bellegarde on the east.

The Jura thus dominates on the north one of the great highways of Europe, on the east and west divides the valleys of the Saône and the Aar, and stretches out to the south so as nearly to join hands with the great mass of the Dauphiné Alps. It therefore j commands the routes from France into Germany, Switzerland, and • Italy, and hence its enormous historical importance.

Let us now examine the topography of the interior of the range. !
This naturally falls into three divisions, each traversed by one of
the three great rivers of the Jura—the Doubs, the Loue, and the
Ain. I

1. In the northern division it is the east and west line which j
prevails—the Lomont, the Mont Terrible, the defile of the Doubs
from St Ursanne to St Hippolyte, and the "Trouée" of the Black
Forest towns. It thus bars access to the central plateau from the
north, and this natural wall does away with the necessity of artificial
fortifications. This division falls again into two distinct portions.
(_) The first is the part east of the deep gorge of the Doubs after
it turns south at St Hippolyte ; it is thus quite cut off on this
side, and is naturally Swiss territory. It includes the basin of
the river Birs, and the great plateau between the Doubs and the
Aar, on which, at an average height of 2600 feet, are situated a
number of towns, one of the most striking features of the Jura.
These include Locle and La Chaux de Fonds, and are mainly occu-
pied with watchmaking, an industry which does not require bulky
machinery, and is therefore well fitted for a mountain district.
(_) The part west of the " Cluse" of the Doubs.—Of this, the
district east of the river Dessoubre, isolated in the interior of the
range (unlike the Locle plateau), is called the "Saute Montagne,"
and is given up to cheese making, curing of hams, saw mills, &e.
But little watchmaking is carried on there, Besançon being the
chief French centre of this industry, and being connected with
Geneva by a chain of places similarly occupied, which fringe the
west plateau of the Jura. The part west of the Dessoubre, or the
Moyenne Montagne, a huge plateau north of the Loue, is more espe-
cially devoted to agriculture, while along its north edge metal work-
ing and manufacture of hardware are carried on, particularly at
Besançon and Audineourt.

2. The central division is remarkable for being without the deep
gorges which are found so frequently in other parts of the range.
It consists of the basin of which Pontarlier is the centre, through
notches in the rim of which routes converge from every direction ;
this is the great characteristic of the middle region of the Jura. |
Hence its immense strategical and commercial importance. On the
north-east roads run to Morteau and Locle, on the north-west to !
Besançon, on the west to Salins, on the south-west to Dole and Lons- ;
le-Saunier, on the east to the Swiss plain. The Pontarlier plateau
is nearly horizontal, the slight indentations in it being due to
erosion, e.g., by the river Drugeon. The keys to this important
plateau are to the east the Fort de Joux, under the walls of which
meet the two lines of railway from Neuchâtel, and to the west
Salins, the meeting place of the routes from the Col de la Faucille, ;
from Besançon, and from the French plain.

The Ain rises on the south edge of this plateau, and on a lower
shelf or step, which it waters, are situated two points of great
military importance—Kozeroy and Champagnole. The latter is
specially important, since the road leading thence to Geneva
traverses one after another, not far from their head, the chief valleys
which run down into the South Jura, and thus commands the
southern routes as well as those by St Cergues and the Col de la
Faucille from the Geneva region, and a branch route along the Orbe
river from Jougne. The fort of Les Rousses, near the foot of the
Dole, serves as an advanced post to Champagnole, just as the
Fort de Joux does to Pontarlier. t

The above sketch will serve to show the character of the central Jura as the meeting place of routes from all sides, and the import-

ance to France of its being strongly fortified, lest an enemy ap-proaching from the north-east should try to turn the fortresses of the " Trouée de Belfort." It is in the western part of the central Jura that the north and south lines first appear strongly marked. There are said to be in this district no less than fifteen ridges run-ning parallel to each other, and it is these which force the Loue to the north, and thereby occasion its very eccentric course. The cultivation of wormwood wherewith to make the tonic " absinthe" has its headquarters at Pontarlier.

3. The southern division is by far the most complicated and en-tangled part of the Jura. The lofty ridge which bounds it to the east forces all its drainage to the west, and the result is a number of valleys of erosion (of which that of the Ain is the chief instance), quite distinct from the natural " cluses " or fissures of those of the Doubs and of the Loue. Another point of interest is the number of roads which intersect it, despite its extreme irregularity. This is due to the great " cluses " of Nantua and Virieu, which traverse it from east to west. The north and south line is very clearly seen in the eastern part of this division ; the north-east and south-west is entirely wanting, but in the Villebois range south of Ambérieu we have the principal example of the north-west to south-east line. The plateaus west of the Ain are cut through by the valleys of the Valouse and of the Surand, and like all the lowest terraces on the west slope do not possess any considerable towns. The Ain receives three tributaries from the east:—

(a) The Bienne, which flows from the fort of Les Rousses by St Claude, the industrial centre of the South Jura, famous for the manufacture of wooden toys, owing to the large quantity of box-wood in the neighbourhood. Septmoncel is busied with cutting of gems, and Morez with watch and spectacle making. Cut off to the east by the great chain, the industrial prosperity of this valley is of recent origin.

(b) The Oignon, which flows from south to north. It receives the drainage of the lake of Nantua, a town noted for combs and silk weaving, and which communicates by the "cluse" of the Lac de Silan with the Valserine valley, and so with the Rhone at Belle-garde, and again with the various routes which meet under the walls of the fort of Les Rousses, while by the Val Romey and the Séran Culoz is easily gained.

(c) The Albarine, connected with Culoz by the "cluse" of Virieu, and by the Furan flowing south with Belley, the capital of the district of Bugey (the old name for the South Jura).
The "cluses" of Nantua and Virieu are now both traversed by important railways ; and it is even truer than of old that the keys of the South Jura are Lyons and Geneva. But of course the strategic importance of these gorges is less than appears at first sight, because they can be turned by following the Rhone in its great bend to the south.

The name Jura, which occurs in Caesar and in Strabo, is a form of a word which appears under many forms {e.g., Joux, Jorat, Jorasse, Juriens), and is a synonym for a wood or forest. The German name is Leberberg, Leber being a provincial word for a hill.

Politically the Jura is French (departments of the Doubs, Jura, and Ain) and Swiss (parts of the cantons of Geneva, Vaud, Neuchâtel, Bern, Solothurn, and Basel) ; but at its north extremity it takes in a small bit of Alsace (Pfirt or Ferrette). In the Middle Ages the southern, western, and northern sides were parcelled out into a number of districts, all of which were gradually absorbed by the French crown, viz., Gex, Val Bomey, Bresse, and Bugey ^exchanged in 1601 by Savoy for the marquisate of Saluzzo), Franche Comté, or the Free County of Bur-gundy, an imperial fief till annexed in 1674, the county of Montbéliard (Miimpelgard), acquired in 1793, and the county of Ferrette (French 1648-1871). The northern part of the eastern side was held by the bishop of Basel as a fief of the empire, but was given to Bern in 1815 (as a recompense for its loss of Vaud), and now forms the Bernese Jura, a French-speaking district. The centre of the eastern slope formed the principality of Neuchâtel and the county of Vallangin, which were generally held by Burgundian nobles, came by succession to the kings of Prussia in 1707, and were formed into a Swiss canton in 1815, though they did not become free from formal Prussian claims until 1857. The southern part of the eastern slope originally belonged to the house of Savoy, but was con-quered bit by bit by Bern, which was forced in 1815 to accept its subject district Vaud as a colleague and equal in the Swiss Confederation. It was Charles the Bold's defeats at Grandson and Morat which led to the annexa-tion by the Confederates of these portions of Savoyard territory.

See E. F. Berlioux, Le Jura, Paris, 1880 ; Adolphe Joanne, Jura et Alpes Françaises, Paris, 1877 ; Id., Géographies Départementales (the Doubs, Jura, and Ain volumes) ; Charles Sauria, Le Jura pittoresque. (W. A. B. C.)

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