Hydrography.,-- No rivers of importance take their rise in Portugal, and yet few coun tries in proportion to their extent are better supplied with large and navigable streams. The Minho in the north, forming the boundary be tween Spain and Portugal in the lower part of its course; the Douro, first skirting the east frontier and then pursuing its course west to its mouth at Oporto; and the Tagus, all flow east to west; the Guadiana is the only large river of Portugal which deviates from the general westerly direction, and flows mainly south, forming part of the boundary line with Spain. In addition to these rivers, for which Portugal is indebted to Spain, the purely local rivers are the Vouga, Mondego and Sado. Numerous small lakes are scattered over the plains and among the mountains and valleys. The fish eries, especially those of sardine and tunny, are of considerable commercial importance, giving employment to about 45,000 people. The yearly catch is worth $5,000,000.
Geology and Mineral Resources.— The nu cleus of the mountains is usually granite, over lain in the north by micaceous schist and other metamorphic rocks. Crystalline rocks and Palaeozoic formations (especially Silurian) oc cupy about two-thirds of the surface, but the Jurassic, the Cretaceous and various Tertiary formations are also represented in the more southerly parts of the country. Volcanic for mations are very apparent in the Serra de Caldeirao, forming a continuation of that of Monchique. The mineralogical treasures seem more remarkable for their variety than for their value, though some are, and many more it is supposed might be, worked to advantage. They include argentiferous lead, copper, iron, cobalt, bismuth, antimony, fine marble, slate, saltpeter, lithographic stones, mill-stones and porcelain earth. Some gold also is washed from the sands of the Douro, Mondego and other streams, and in several serras, particularly those of Estrella and Gerez-Larouco; and many valuable pebbles and rock-crystals are found in a great number of places. Large quantities of salt are formed in bays along the coast by natural evaporation; there are numerous salt marshes; and over 200 mineral springs, mostly impregnated with sulphur.
Climate.— The climate is greatly modified by the proximity of the sea and the height of the mountains, the former tempering the excessive heat of summer by refreshing breezes and the latter making the winter more rigorous than usual in countries under the same latitude. In general, however, winter is both short and mild, and in some places never completely interrupts the course of vegetation. In consequence of this many parts of Portugal enjoy the benefit of a double spring. Early in February vegetation is in full vigor; the plants shoot forth rapidly, attain maturity and either wither away or if of economical value are gathered and harvested. During the month of July the heat is often extreme, and, rain seldom falling, the whole country, particularly at its lower levels and along the coast, assumes a very parched appear ance. The drought generally continues through
out August and far into September; but at last the sky, which had previously been serene, becomes overcast and copious showers descend. The second spring now begins, and the fields again become covered with flowers and verdure. Winter begins at the end of November. In the mountainous districts the loftier summits qbtain a covering of snow and retain it for a greater or less period according to their altitude; but in all the country south of the Douro, and at a moderate elevation, snow generally soon melti away. The mean annual temperature in the north of Portugal is about 50° F., and of the south 65°. Deluges of rain, however, continue to fall, with occasional violent hurricanes thunderstorms. Shocks of earthquake are some times felt, particularly in the vicinity of the metropolis, where those of 1755 were over whelmingly disastrous.
Forestry, Flora and Fauna.— Many of the mountains are clothed with fine forests, chiefly pine and oak, both the ordinary species, or Quercus robur, and the cork-tree, or Q. sober, are conspicuous. In the central provinces, at a moderate elevation, magnificent chestnuts are very prevalent. Nearly one-sixth of the country's area is in timber, there being 2,000,000 acres of pines, over 1,000,000 acres of oaks, 800,000 acres of cork-trees and 210,000 of chest nut. In the south, in the province of Algarve, both the date and the American aloe are not uncommon. There are few countries with a more varied flora than Portugal. The number of species has been estimated to exceed 4,000, and of these more than 3,000 are phanerogam ous. Both the flora and fauna of the kingdom are similar to those of Spain (q.v.).
Land Tenure, Agriculture and Stock-Rais ing.— The common forms of land tenure are peasant proprietorship, tenant farming, metay age and emphyteusis (ground rent). Large estates and tenant farming are common in the south; peasant proprietorship and emphyteusis prevail in the north. Agriculture is just about equal to the country's needs, one-fourth of the area being in cereals or grass and 7 per cent in vineyards and fruit orchards, 17 per cent under forest and 43 per cent is waste land. Barley and rye are important crops in the north, else where wheat and maize are of more importance. In swampy localities some rice is grown. The production in 1916 was: wheat, 7,115,790 bushels; rye, 2,676,107 bushels; oats, 3,189,078 bushels; barley, 1,158,461 bushels; beans, 1,102, 401 bushels; potates, 1,709,527 hundredweight. In the north the chief products are maize and oxen, in the central region, wheat and maize and in the south, wheat and swine. Wine is produced in large quantities. In 1917 the vin tage amounted to 109,808,265 gallons. Olive oil was produced the same year to the extent of 362,094,084 gallons. Figs and tomatoes are also important crops.