The basin of the Loire, with an area of about 47,000 sq. m., includes a great part of central and western France or nearly a quarter of the whole country. The Loire rises in Mont Gerbier de Jonc, in the range of the Vivarais mountains, flows due north to Nevers, then turns to the north-west as far as Orléans, in the neighbourhood of which it separates the marshy region of the Sologne (q.v.) on the south from the wheat-growing region of Beauce and the Gâtinais on the north. Below Orléans it takes its course towards the south-west, and lastly from Saumur runs west, till it reaches the Atlantic between Paimbœuf and St Nazaire. On the right the Loire receives the waters of the Furens, the Arroux, the Nièvre, the Maine (formed by the Mayenne and the Sarthe with its affluent the Loir), and the Erdre, which joins the Loire at Nantes; on the left, the Allier (which receives the Dore and the Sioule), the Loiret, the Cher, the Indre, the Vienne with its affluent the Creuse, the Thouet, and the Sèvre-Nantaise. The peninsula of Brittany and the coasts of Normandy on both sides of the Seine estuary are watered by numerous independent streams. Amongst these the Vilaine, which passes Rennes and Redon, waters, with its tributaries, an area of 4200 sq. m. The Orne, which rises in the hills of Normandy and falls into the Channel below Caen, is of considerably less importance.
The basin of the Seine, though its area of a little over 30,000 sq. m. is smaller than that of any of the other main systems, comprises the finest network of navigable rivers in the country. It is by far the most important basin of northern France, those of the Somme and Scheldt in the north-west together covering less than 5000 sq. m., those of the Meuse and the Rhine in the north-east less than 7000 sq. m. The Seine descends from the Langres plateau, flows north-west down to Méry, turns to the west, resumes its north-westerly direction at Montereau, passes through Paris and Rouen and discharges itself into the Channel between Le Havre and Honfleur. Its affluents are, on the right, the Aube; the Marne, which joins the Seine at Charenton near Paris; the Oise, which has its source in Belgium and is enlarged by the Aisne; and the Epte; on the left the Yonne, the Loing, the Essonne, the Eure and the Rille.
Lakes.—France has very few lakes. The Lake of Geneva, which forms 32 m. of the frontier, belongs to Switzerland. The most important French lake is that of Grand-Lieu, between Nantes and Paimbœuf (Loire-Inférieure), which presents a surface of 17,300 acres. There may also be mentioned the lakes of Bourget and Annecy (both in Savoy), St Point (Jura), Paladru (Isère) and Nantua (Ain). The marshy districts of Sologne, Brenne, Landes and Dombes still contain large undrained tracts. The coasts present a number of maritime inlets, forming inland bays, which communicate with the sea by channels of greater or less width. Some of these are on the south-west coast, in the Landes, as Carcans, Lacanau, Biscarosse, Cazau, Sanguinet; but more are to be found in the south and south-east, in Languedoc and Provence, as Leucate, Sigean, Thau, Vaccarès, Berre, &c. Their want of depth prevents them from serving as roadsteads for shipping, and they are useful chiefly for fishing or for the manufacture of bay-salt.
Climate.—The north and north-west of France bear a great resemblance, both in temperature and produce, to the south of England, rain occurring frequently, and the country being consequently suited for pasture. In the interior the rains are less frequent, but when they occur are far more heavy, so that there is much less difference in the annual rainfall there as compared with the rest of the country than in the number of rainy days. The annual rainfall for the whole of France averages about 32 in. The precipitation is greatest on the Atlantic seaboard and in the elevated regions of the interior. It attains over 60 in. in the basin of the Adour (71 in. at the western extremity of the Pyrenees), and nearly as much in the Vosges, Morvan, Cévennes and parts of the central plateau. The zone of level country extending from Reims and Troyes to Angers and Poitiers, with the exception of the Loire valley and the Brie, receives less than 24 in. of rain annually (Paris about 23 in.), as also does the Mediterranean coast west of Marseilles. The prevailing winds, mild and humid, are west winds from the Atlantic; continental climatic influence makes itself felt in the east wind, which is frequent in winter and in the east of France, while the mistral, a violent wind from the north-west, is characteristic of the Mediterranean region. The local climates of France may be grouped under the following seven designations: (1) Sequan climate, characterizing the Seine basin and northern France, with a mean temperature of 50° F., the winters being cold, the summers mild; (2) Breton climate, with a mean temperature of 51.8° F., the winters being mild, the summers temperate, it is characterized by west and south-west winds and frequent fine rains; (3) Girondin climate (characterizing Bordeaux, Agen, Pau, &c.), having a mean of 53.6° F., with mild winters and hot summers, the prevailing wind is from the north-west, the average rainfall about 28 in.; (4) Auvergne climate, comprising the Cévennes, central plateau, Clermont, Limoges and Rodez, mean temperature 51.8° F., with cold winters and hot summers; (5) Vosges climate (comprehending Epinal, Mézières and Nancy), having a mean of 48.2° F., with long and severe winters and hot and rainy summers; (6) Rhône climate (experienced by Lyons, Chalon, Mâcon, Grenoble) mean temperature 51.8° F., with cold and wet winters and hot summers, the prevailing winds are north and south; (7) Mediterranean climate, ruling at Valence, Nîmes, Nice and Marseilles, mean temperature, 57.5° F., with mild winters and hot and almost rainless summers.
Flora and Fauna.—The flora of southern France and the Mediterranean is distinct from that of the rest of the country, which does not differ in vegetation from western Europe generally. Evergreens predominate in the south, where grow subtropical plants such as the myrtle, arbutus, laurel, holm-oak, olive and fig; varieties of the same kind are also found on the Atlantic coast (as far north as the Cotentin), where the humidity and mildness of the climate favour their growth. The orange, date-palm and eucalyptus have been acclimatized on the coast of Provence and the Riviera. Other trees of southern France are the cork-oak and the Aleppo and maritime pines. In north and central France the chief trees are the oak, the beech, rare south of the Loire, and the hornbeam; less important varieties are the birch, poplar, ash, elm and walnut. The chestnut covers considerable areas in Périgord, Limousin and Béarn; resinous trees (firs, pines, larches, &c.) form fine forests in the Vosges and Jura.
The indigenous fauna include the bear, now very rare but still found in the Alps and Pyrenees, the wolf, harbouring chiefly in the Cévennes and Vosges, but in continually decreasing areas; the fox, marten, badger, weasel, otter, the beaver in the extreme south of the Rhône valley, and in the Alps the marmot; the red deer and roe deer are preserved in many of the forests, and the wild boar is found in several districts; the chamois and wild goat survive in the Pyrenees and Alps. Hares, rabbits and squirrels are common. Among birds of prey may be mentioned the eagle and various species of hawk, and among game-birds the partridge and pheasant. The reptiles include the ringed-snake, slow-worm, viper and lizard.
(R. Tr.)
Geology.—Many years ago it was pointed out by Élíe de Beaumont and Dufrénoy that the Jurassic rocks of France form upon the map an incomplete figure of 8. Within the northern circle of the 8 lie the Mesozoic and Tertiary beds of the Paris basin, dipping inwards; within the southern circle lie the ancient rocks of the Central Plateau, from which the later beds dip outwards. Outside the northern circle lie on the west the folded Palaeozoic rocks of Brittany, and on the north the Palaeozoic massif of the Ardennes. Outside the southern circle lie on the west the Mesozoic and Tertiary beds of the basin of the Garonne, with the Pyrenees beyond, and on the east the Mesozoic and Tertiary beds of the valley of the Rhône, with the Alps beyond.
In the geological history of France there have been two great periods of folding since Archean times. The first of these occurred towards the close of the Palaeozoic era, when a great mountain system was raised in the north running approximately from E. to W., and another chain arose in the south, running from S.W. to N.E. Of the former the remnants are now seen in Brittany and the Ardennes; of the latter the Cévennes and the Montagne Noire are the last traces visible on the surface. The second great folding took place in Tertiary times, and to it was due the final elevation of the Jura and the Western Alps and of the Pyrenees. No great mountain chain was ever raised by a single effort, and folding went on to some extent in other periods besides those mentioned. There were, moreover, other and broader oscillations which raised or lowered extensive areas without much crumpling of the strata, and to these are due some of the most important breaks in the geological series.
The oldest rocks, the gneisses and schists of the Archean period, form nearly the whole of the Central Plateau, and are also exposed in the axes of the folds in Brittany. The Central Plateau has probably been a land mass ever since this period, but the rest of the country was flooded by the Palaeozoic sea. The earlier deposits of that sea now rise to the surface in Brittany, the Ardennes, the Montagne Noire and the Cévennes, and in all these regions they are intensely folded. Towards the close of the Palaeozoic era France had become a part of a great continent; in the north the Coal Measures of the Boulonnais and the Nord were laid down in direct connexion with those of Belgium and England, while in the Central Plateau the Coal Measures were deposited in isolated and scattered basins. The Permian and Triassic deposits were also, for the most part, of continental origin; but with the formation of the Rhaetic beds the sea again began to spread, and throughout the greater part of the Jurassic period it covered nearly the whole of the country except the Central Plateau, Brittany and the Ardennes. Towards the end of the period, however, during the deposition of the Portlandian beds, the sea again retreated, and in the early part of the Cretaceous period was limited (in France) to the catchment basins of the Saône and Rhône—in the Paris basin the contemporaneous deposits were chiefly estuarine and were confined to the northern and eastern rim. Beginning with the Aptian and Albian the sea again gradually spread over the country and attained its maximum in the early part of the Senonian epoch, when once more the ancient massifs of the Central Plateau, Brittany and the Ardennes, alone rose above the waves. There was still, however, a well-marked difference between the deposits of the northern and the southern parts of France, the former consisting of chalk, as in England, and the latter of sandstones and limestones with Hippurites. During the later part of the Cretaceous period the sea gradually retreated and left the whole country dry.