very complete sequence of formations from the Lias to those of recent date. An interesting and orderly petrological sequence of Tertiary igneous rocks has been determined.
Archean rocks form the cores of the ancient crystalline masses within the littoral zone from Algiers to Bona. They consist of gneiss, mica-schist, quartzites, crystalline limestones and conglomerates. Primary deposits are doubtfully represented by the detached fragments of unfossiliferous strata of Traras, Blida and east of Orleansville. Carboniferous and Permian strata are possibly represented by some black and grey micaceous shales with beds of coal in the Jurjura. At Jebel-kahar and west of Traras, Pomel attributes certain conglomerates, red sandstones and purple and green shales to the Permian. The rocks of Secondary and Tertiary ages have been profoundly affected by the Alpine movements, and are thrown into a series of complex folds, so that in numerous instances their stratigraphy is imperfectly understood. The gypsiferous and saliferous marls of Shellata, Suk Ahras and Ain Nussi have yielded Triassic fossils. Triassic rocks are considered to be present in Constantine and in the Jurjura. Rhaetic beds (Infra Lias), consisting of dolomites and siliceous limestones, have been recognized at Saida. The lower and middle divisions of the Jurassic, composed of massive limestones more or less siliceous and overlain by the marls and highly fossiliferous limestones of the Upper Lias, play an important part in the constitution of the chief mountains of the Tell. In south Oran they determine the principal axes of the mountain ranges. The Inferior Cretaceous rocks include the Neocomian and Gault (Albian and Aptian) subdivisions, and form the flanks of the mountains in the Tell. In the south the Albian subdivision of the Gault is alone represented. Rocks of Upper Cretaceous age are represented in all their stages. The Cenomanian presents two distinct facies. North of the Atlas it belongs to the European type, in the south it contains a fauna of oysters and sea-urchins belonging to the facies “africano-syrian” of Zittel. There is a continuous transition between the Senonian and Danian, proving that the Algerian region did not participate in the immersion which occurred in Provence and in the Corbieres of southern France during the Danian epoch. The Lower Eocene rocks contain the chief phosphatic deposits of Algeria, those of the Tebessa region being the best known. Certain species of nummulites, which are very common, distinguish the various subdivisions of the Eocene. The highest beds, consisting of quartzites, shales, marls and sandstones with the remains of fucoids, are found in the Jurjura and Shellata. The Oligocene period consists of a marine phase confined to the littoral zone of Kabylia, and of a continental phase occupying vast areas composed of lacustrine, alluvial, gypsiferous marls, sandstones and conglomerates. The Miocene formation obtains its greatest development in Oran and is much expanded in the Tell. At the close of the Lower Miocene period (beds with Ostrea crassissima) great modifications in the relief and limits of the Algerian formations took place. Hitherto marine conditions were confined to the littoral; in Middle Miocene times (Helvetian) the sea broke in and spread in a south-east direction in the form of long ramified fjords but did not extend as far as the Sahara. To the Pliocene period the marine deposits of the Sahel of Algiers and of the Sahel Jijelli must be attributed; also the lacustrine marls and limestone of the basin of Constantine, and the ancient alluviums of the basins and depressions which bear no relation to the existing valleys. Among the Tertiary volcanic rocks those of acid types (granites, granulites) were the first to appear and are developed latitudinally; rocks of intermediate type (dacites, andesites) characterize the Miocene and early Pliocene periods; while the basic rocks (ophites, elaeolite syenites and basalts) attained their maximum in later Pliocene and Quaternary times. Their development, feeble as compared with the acid rocks, is meridional. The Quaternary period includes an older stage containing fragments of fossils from the underlying formations; a later stage containing the bones of Hippopotamus, Elephas, Rhinoceros, Camelus, Equus; and finally the vast accumulations of sand which began to be formed in prehistoric times. The broad platforms of the hamada are covered with Quaternary deposits. (W. G.*)]
Climate.—Although Algeria enjoys a warm climate, the temperature varies considerably in different parts, according to the elevation and configuration of the country. Along the coast the weather is very mild, the thermometer rarely falling to freezing-point even in winter. The coldest month is January, the hottest August. The mean annual temperature in the coast plains is 66° F. Heavy rains prevail from December to March, and rain is not uncommon during other months also, excepting June, July, August and September, which are very hot and rainless. The average annual fall is 29 in. On the mountains and the high plateaus the winter is often very severe; snow lies for six months on the higher peaks of the Kabyle mountains. On the plateaus the temperature passes from one extreme to the other, and rain seldom falls. (For the climate of the Saharan region see Sahara.) Throughout Algeria, especially in the summer, there is a great difference between day and night temperature, notably in the inland districts. Between May and September the sirocco, or hot wind of the desert, sweeps at intervals over the country, impregnating the air with fine sand; but in general, with the exception of the vicinity of the marshes, the climate is healthy. Its salubrity has been increased by the draining of many marshes in the neighbourhood of the larger towns.
Fauna and Flora.—The fauna of Algeria resembles that of the Mediterranean system generally, though many animals once common to South Europe and North Africa—such as the lion, panther, hyena and jackal—are now extinct in Europe. Lions, formerly plentiful, have disappeared, and leopards and panthers are rare; but jackals, hyenas and Algerian apes are not uncommon. Wild boars are found in the oak forests, and brown bears in the uplands. In the south are various species of antelope and wild goat. Red deer (Cervus elaphus barbarus), which differ from the typical European species only in the fact that the second tine is absent from their antlers, a peculiarity which they share with the red deer of Spain and Corsica, are still found in the forest of Beni Saleh in the department of Constantine, but are being exterminated by forest fires and poaching Arabs. Of domestic animals the camel and sheep are the most important. The chief wealth of the Arab tribes of the plateaus consists in their immense flocks of sheep. The horses and mules of Algeria are noted; and the native cattle are an excellent stock on which to graft the better European varieties. Of birds, eagles, vultures, hawks, owls and quails are common; snipe, curlews, plovers, storks and herons frequent the marshy parts; and the ostrich the desert. Partridges and woodcocks are fairly common. Among the reptiles are various species of serpents, tortoises, turtles, lizards, &c. Locusts are common and sometimes do great damage. Scorpions are numerous in the arid regions. Algerian prawns, especially those of Bona, are large and of a delicate flavour. Of the twenty-one species of freshwater fish, five are peculiar to the country, but none is of much economic value save the barbel and eel. A species of trout is found in the streams near Collo, but in none of the other rivers.
The flora of Algeria consists of about 3000 species, of which some 450 are indigenous to the country, 100 being peculiar to the Sahara. The flora of the Tell is South European in character. The agave and prickly pear, the myrtle, the olive and the dwarf palm grow luxuriantly; and the fields are covered with narcissus, iris and other flowers of every hue. Roses, geraniums, and the like, bloom throughout the winter. The flora of the high plateaus consists chiefly of grasses, notably various kinds of alfa or esparto, and aromatic herbs. In the Saharan oases the characteristic tree is the date palm—“the king of the desert.” Over 11,000 sq. m. of the mountainous country near the coast are covered with forests of various species of oak, pine, fir, cedar, elm, ash, maple, olive, many of them of gigantic size, and other trees; and on the slopes of the mountains up to 3800 ft. above the sea the fig is common. Its fruit forms one of the staple articles of food among the Kabyles. Cork and carob trees are also very common. A magnificent conifer, the Atlantic
