AMAZON - THE MAIN RIVER Physical Characteristics.—TheAMAZON MAIN RIVER is navigable for ocean steamers as far as Iquitos, 2,3oom. from the sea, and 486m. higher up for vessels drawing 14f t. of water, as far as Achual Point. Beyond that, according to Tucker, confirmed by Wertheman, it is unsafe ; but small steamers frequently ascend to the Pongo de Manseriche, just above Achual Point. The average current of the Amazon is about 3m. an hour; but, especially in flood, it dashes through some of its contracted channels at 5m. an hour. The U.S. steamer "Wilmington" as cended it to Iquitos in 1899. Commander Todd reports that the average depth of the river in the height of the rainy season is 120 feet. It commences to rise in November, and increases in volume until June, and then falls until the end of October. The rise of the Negro branch is not synchronous; for the steady rains do not commence in its valley until February or March. By June it is full, and then it begins to fall with the Amazon. The Amazon at times broadens to 4 and 6 miles. Occasionally, for long distances, it divides into two main streams, with inland, lateral channels, all connected by a complicated system of natural canals, cutting the low, flat igapo (recent alluvial) lands, which are never more than 15ft. above low river, into almost numberless islands. At the narrows of Obidos, 400m. from the sea, it is com pressed into a single bed a mile wide and over 2ooft. deep, through which the water flows at the rate of 4 to 5m. an hour. In the rainy season it inundates the country throughout its course to the extent of several hundred thousand square miles, covering the flood-plain, called vargem (land between the levels of moderate and high floods). The flood-levels are in places from 4o to soft high above low river. Taking four roughly equidistant places, the rise at Iquitos is loft., at Teffe 45, near Obidos 35, and at Para 12.
The first high land met in ascending the river is on the north bank, opposite the mouth of the Xingu, and extends for about i5om. up, as far as Monte Alegre. It is a series of steep, table topped hills, cut down to a kind of terrace which lies between them and the river. Monte Alegre reaches an altitude of several hundred feet. On the south side, above the Xingu, a line of low bluffs extends_ in a series of gentle curves with hardly any breaks nearly to Santarem, but a considerable distance inland, bordering the flood-plain, which is many miles wide. Then they bend to the south-west, and, abutting upon the lower Tapajos, merge into the bluffs which form the terrace margin of that river valley. The next high land on the north side is Obidos, a bluff, 56f t. above the river, backed by low hills. From Serpa, nearly opposite the river Madeira, to near the mouth of the Rio Negro, the banks are low, until approaching Mangos, they are rolling hills; but from the Negro, for 600m., as far up as the village of Canaria, at the great bend of the Amazon, only very low land is found, resembling that at the mouth of the river.
On the south side, from the Tapajos to the river Madeira, the banks are usually low, although two or three hills break the general monotony. From the latter river, however, to the Ucayali, a distance of nearly 1,5oom., the forested banks are just out of water, and are inundated long before the river attains its maxi mum flood-line. Thence to the Huallaga the elevation of the land is somewhat greater ; but not until this river is passed, and the Pongo de Manseriche approached, does the swelling ground of the Andean foot-hills raise the country above flood-level.
The Amazon is not a continuous incline, but probably consists of long, level stretches connected by short inclined planes of extremely little fall, sufficient, however, owing to its great depth, to give the gigantic volume of water a continuous impulse towards the ocean. The lower Amazon presents every evidence of having once been an ocean gulf, the upper waters of which washed the cliffs near Obidos. Only about io% of the water discharged by the mighty stream enters it below Obidos, very little of which is from the northern slope of the valley. The drainage area of the Amazon basin above Obidos is about 1,945,000sq.m., and, below, only about 423,000sq.m., or say 20%, exclusive of the sq.m. of the Tocantins basin.
The width of the mouth of the river is usually measured from Cabo do Norte to Punto Patijoca, a distance of 207 statute m.; but this includes the ocean outlet, 4om. wide, of the Para river, which should be deducted, as this stream is only the lower reach of the Tocantins. It also includes the ocean frontage of Marajo, an island about the size of the kingdom of Denmark lying in the mouth of the Amazon. Following the coast, a little to the north of Cabo do Norte, and for mom. along its Guiana margin up the Amazon, is a belt of half-submerged islands and shallow sand banks. Here the tidal phenomenon called the bore, or Pororoca, occurs, where the soundings are not over 4 fathoms. It com mences with a roar, constantly increasing, and advances at the rate of from 10 to 15m. an hour, with a breaking wall of water from 5 to 12 f t. high. Under such conditions of warfare between the ocean and the river, it is not surprising that the ocean is rapidly eating away the coast and that the vast volume of silt carried by the Amazon finds it impossible to build up a delta.
The Amazon averages five miles in width for a long distance but is 400 miles wide in its lower course. In the wet season a belt of as much as 20 miles width may flood on each side.
The economic vicissitudes through which the Amazon basin has passed in late years are traceable largely to changes in the rubber industry. Although crude rubber was sent from the Amazon as early as 1827, several decades passed before the annual exportation attained commercial importance. With the remark able increase in the demand for rubber, prices rose, and gatherers in the forests were sent further afield.
About 1910-11 prices reached their highest point, yearly ex portations amounted to thousands of tons and numerous river craft plied on the Amazon and its tributaries. The inhabitants of the valley were almost exclusively engaged in rubber exploitation. The growing of foods was largely abandoned, even necessary commodities being imported. About this period, however, planta tion rubber trees of the East Indies were coming into bearing and the result was a collapse by 1915 of the one great industry of the region. During the five years ending in 1927 there was a gradual increase of rubber exportation from the Amazon region, the total shipments for 1927 being in excess of 28,700 long tons.
A land concession of 3,70o,000ac. granted by Brazil in 1927 to the Ford Motor Company, Detroit, Mich., and the formation of a Brazilian subsidiary with Brazilian stockholders provide large capital for the development of plantation rubber. The land lies along the eastern side of the Tapajos river 125 to 15om. south of Santarem on the Amazon. The two rivers afford suf ficient water depth for ocean-going vessels to traffic directly with the plantations, work upon which is progressing.
Estimates place the population of the Amazon basin at about 2,000,00o, all but 200,000 being credited to Brazil. The city of Belem had 279,491 in 1930; Mangos, 83,736; Iquitos, io,000; San tarem, 6,000; Obidos, 30,000. It is estimated that in the Amazon basin about 30,000 labourers might be recruited for agricultural or other purposes. Quantities of rubber, Brazil-nuts, fish and other products were being exported in 1925. The region's imports were also on the increase.
Expeditions.—Duringthe period 1910-27 there were numer ous expeditions, exploratory and scientific, into regions watered by the Amazon and its tributaries. Roosevelt and Rondon in 1913-14 in a notable trip down the so-called River of Doubt in two months covered 470 miles of this river, hitherto unknown except to rubber-gatherers and found it to be a branch of the Madeira, joining it at 5° 21' S. lat. The Fleming expedition (1919) studied the industrial possibilities of the region and Rice in a series of expeditions (1910 to 1924) made accurate surveys of the Negro, Uaupes and Branco. A Carnegie Museum expedi tion made a study of fishes; the Ellsworth, Farabee, Fawcett and other parties obtained geographic, geological and ethnographical data. In 1923-24 the American Rubber Mission financed by the U.S. Government conducted a survey along a total of 37 water ways including the Tocantins, Xingu, Tapajos, Madeira, Mamore, Beni, Madre de Dios, Acre, Purus, Ucayali, Huallaga, Negro and Branco. Special parties penetrated inland and examined soils and agricultural possibilities particularly with a view to the cul tivation of rubber and sugar cane. Its leader, Dr. W. L. Schurz, was assisted by specialists from the U.S. Departments of Com merce and Agriculture (among them Dr. C. F. Marbut of the Bureau of Soils) and from the business world, and by experts from Brazil, Bolivia and Peru. In 1927 and 1928 the American Geographical Society, in connection with its work of collecting source material for the new map of Hispanic America on the millionth scale which the Society is producing from original sources, sponsored two expeditions to the Amazon Basin. Joseph H. Sinclair, the leader of one of these parties continued his sur veys of the sources of the Napo River begun in 1921 and located a new volcano. The other, conducted by O. M. Miller, of the Society's. School of Surveying, made reconnaissance surveys in Central Peru, including a topographic survey of the sources of the Maranon.
Early in 1925 Col. P. W. Fawcett, British explorer, with a small party left Cuyaba to explore the Xingu-Tapajos region of Brazil. After some months news ceased to come from the party and it was feared that they were lost. In 1928 Commander G. M. Dyott, of England, sailed from New York with a relief party, retraced Fawcett's route for some distance and reported that he had found evidence that the party had been killed by Indian. (X.) BIBLIOGRAPHY.-S. Fritz, Journal of the Travels and Labors of Bibliography.-S. Fritz, Journal of the Travels and Labors of Father Samuel Fritz in the River of the Amazons Between 1686 and 1723, trans. and edit. by G. Edmundson (1922) ; J. A. Williamson, Eng lish Colonies in Guiana and on the Amazon, 16°4-1668 (1923) ; G. MacCreagh, White Waters and Black (1926) ; W. M. McGovern, Jungle Paths and Inca Ruins (1927) Flora.—In diversity of forms and profusion of individuals the plant life of the Amazon river basin is probably the richest on the globe. Within the area drained by this river system, species of practically every oecological type find homes. Here most of the idiosyncrasies of the plant kingdom are in evidence, for this enormous territory presents a myriad-faced environment, and each face has its own peculiar complement of plant inhabitants. There are few parts of the earth's surface where the struggle for exist ence appears so intense, for plants literally swarm here.
Nearly all types of plant associations occur and many of these have native names, such as monte, montana (forest), varzia (overflow forest), curiche (swampy meadow), campo, pampa (prairie or park-like country), aninga (araceous swamps, mostly of the arborescent relative of the calla-lily, Montrichardia arbores cens), terra firma (in Brazil, land rarely, if ever, overflowed), ceja (bush, copse or chaparral), pajonales (small grass lands), paramos and paramillos (large and small alpine meadows).
The dominant feature of this area is the great forest—an ex panse of green-topped columns that stretch from a Zoom. front on the Atlantic in an ever-widening angle, almost across the con tinent to the snow-capped Andes. It ranges from the swampy tidewater mangrove thickets at sea-level to the bush country that marks the tree limit on the Andes at from 1 o,000 to 12,000f t. alti tude, where the last arborescent remnants hug the stream borders.
The most striking characteristics of these vast woods are the comparative absence of pure stands of any tree species; the pau city of forest giants in large groups; the division of the vertical height of the forest into storeys or floors on account of the mass effects of the various growths as regards size ; the multitudes of very different types, both as to form and habit, jumbled together, often in the most tangled confusion ; the general absence of sea sonal leaf-fall and flowering time; the small percentage of soft woods; th8 number of tree forms with prop-roots or buttressed trunks; the long distance between the forest floor and the first branches; the absence of great masses of floral colour and, com paratively speaking, the light colour of the bark.
In the temperate zones, solid forests of one or a few species are characteristic, so that they are designated under the name of their dominant species, such as oak or pine forests. On an acre of Amazon forest, in most regions, scores of species occur, but only a few individuals of each, although there are considerable areas that might be called laurel forests.
Palms, myrtles, laurels, acacias, bignonias, cedrelas, cqcropias, rosewoods, bombacaceas, Brazil-nuts, rubber trees, figs, purple hearts and dozens of others often grow on one small area. Within a half-mile square, Agassiz counted different woods. In some regions, particularly rain forest on certain mountain slopes, tree ferns add to the variety. Conifers are practically absent.
In general, forest giants stand alone and are conspicuous against the sky-line because they number so few. They rarely exceed 2ooft. and probably the average tree height of the larger growing species is not over zoo feet. Examples of species that attain the greatest height are the Brazilian cow-tree or massarandicba (Mimu sops elata), the silk-cotton (kapok) or samauma (Eriodendron sp.), pau d'arco (Tecoma sp.), liacori (Symphonea sp.), Brazil nut or castanheira (Bertholletia sp.), and the cream-nut or sapu caia (Lecythis ollaria). Species of fig and garlic trees (Gallesia) also reach huge proportions. As one stands in the midst of a typical section of the Amazonian wilderness, nothing is perhaps more impressive or full of greater contrast than the changing scenes presented as one glances from the forest floor to its blue apertured, sky-faced ceiling.
Often the floor level is covered by a mosaic of carpet forms (selaginellas, acantheas, thalias, ferns and bromeliads), beautiful both in design and colour. Beneath the willow-like Tessaria thickets on the sandy river flats meibomias form extensive mats. Gorgeous-hued amaryllids flower in clumps here and there. Our greenhouse lantana is a colourful fragrant weed. Sprays of various orchids cling to sticks, logs and small twigs. Several diminutive species remind one of tiny yellow, brown-splotched pansy sprays made up with equally delicately dimensioned iris leaves. Be gonias, various in foliage and flower colour, are common. Pro fusions of fallen flowers in brilliant vivid shades of red, orange, yellow and pink frequently cover many square yards. Flowering trunks of the wild chocolate, huge buttresses of various forest giants, prop roots of certain palms and many vines and shrubs carry the eye upward to where they branch and leaf.
The second level is where the bushes, tall herbs and slender walking-stick palms flower, leaf and reach their maximum height. Red and yellow heliconias with their enormous banana-like leaves produce luxuriant tropical effects. Slender palms, with orange yellow panicles of male flowers, scent the glades. If fortune fa vours the visitor, the more open areas may be floriferous with the fugitive plum-like bloom of hirtellas and eugenias, or with the clambering types of pink and yellow orchids, sometimes with sprays 5f t. long. Along the river fronts in the higher altitudes (2,00o to 3,000ft.), calliandras with their of brilliant henna-red cockades leave an unforgettable impression. Other typ ical plants of this level in some regions are the panama-hat plant (toquilla), the ivory-nut-palm (tagua), various passion-flowers and bignoniad vines, papayas and cassavas.
Still further the eye ascends to meet the crowns of the various shade-loving trees that form the third storey of the Amazonian forest. These include numerous species of palms (Mauritia, Euterpe, Attalea, Guilielma, Iriartea), the chocolate-tree, the ant-protected tree member of the buckwheat family, Triplar4 or palo de santo, besides hordes of perching orchids, pipers, ferns, cacti, tradescantias, bromeliads and aroids. Finally there is the canopy that fronts the sky, where the sun-loving vines, perchers and larger trees flower and fruit.
Although the valley lies wholly within the tropics, on account of the range in altitude, temperate as well as tropical plants occur, and every marked change in elevation results in a consequent change in the characteristic species. The greatest differentiation in plant life between the various areas is found, generally speak ing, on the outer edge or rim of the basin, where the streams start and the mountain spurs are barriers to the mixing of floras. Hence each mountain valley may have a distinctive flora, and the greater the distance from the delta, in general, the more varied the vege tation over large areas. In some of the peripheral Andean regions, the ascent is so rapid that within a few miles tropical, subtropical and temperate climates are experienced. Bananas, coffee and oranges are grown on the valley floor, while toward the top of the mountain, the climate makes potatoes and barley successful crops. Tropical and temperate types under such conditions are present in strange companionships, such as the trail-side alder (Alnus) loaded with bright-flowered, perching bromeliads, cousins of the pineapple.
The region of the Amazon basin richest in flowers and colour is the ceja or bush country that fringes the tree limit on the eastern flanks of the Andes. Many of the plants recall the tem perate zones, although the species are generally different. Lupines, gentians, barberries, fuchsias, viburnums, lycopodiums, buddleias, raspberries and clematis are typical types.
The high altitudes are treeless and often bleak, barren, stony and full of moors. Grasses (Stipa, Festuca, Calamagrostis) and rushes bulk large, while here and there peculiar relatives of the pineapple (Puya, Pourretia) form small colonies, sentinel-like in habit. Yareta (Azorella), a moss-like cushion plant of the carrot family, furnishes the dwellers in the higher altitudes with part of their fuel. Potatoes, barley, broad beans and native root crops thrive. A lichen (Lecanora sub f usca), growing at i 8,000f t., is said to be the highest altitude reached by plants in these regions.
Between the forest and the low water-line, particularly on the upper Amazon and many of its southern tributaries, but not on the Rio Negro and other "black water" rivers, large areas, often a mile or more in width, are dominated by the tall plumed cane grass, cana brava, a giant relative of the well-known pampas grass. Forest and river usually meet on the "black water" rivers, and small streams of this character are often completely arched by the jungle flora of tree and vine. The grass lands largely lie between the forested valleys of the tributaries or at their head. For the most part, they are park-like in character, sprinkled here and there either with single trees, or with islands of forests from lac. to ioac. or more in extent. Marshy, sluggish, plant-choked streams drain them. Cannas, water-lettuce, water-hyacinth and azqlla cover enormous underwater areas, while much of the up land recalls a temperate prairie.
Some of the most valuable economic plants are indigenous to the Amazon valley. In addition to those already cited, mention should be made of quinine, cacao, cassava (Manihot utilitissima) 'from which tapioca is derived, sarsaparilla, ipecacuanha (the source of ipecac), copaiba, tonka-beans for flavouring tobacco, arnotto (Bixa orellana) for colouring butter and cheese, Para rubber (Hevea), balata, rosewood, snakewood, guava, calabash, coca from which cocaine is derived, chirimoya (one of the world's premier fruits), beans, pineapple and probably the tomato and potato. The giant water-lily (Victoria regia) is not uncommon throughout the basin below i,000ft. altitude, while here the Brazil-nut, bignonia and the potato families attain their greatest development.
the fauna of the Amazon valley is note worthy for the variety and number of its genera and species, it is very deficient not only in species of the larger mammals but also in the individuals of these comparatively few species. In contrast to other regions of the world, a large percentage of the mammals are tree-dwellers. None of them will attack man un provoked, under ordinary circumstances. The monkeys are all arboreal and are common below 3,000f t. altitude. The best known are the red howlers, or guaribas, which make the great forest resound with their morning and evening chorus. Other common species are the spider, night, saki, marmoset, titi and squirrel monkeys. A scarlet-faced, almost tailless species occurs near Ega. All forms are hunted and eaten by the aborigines. There are six species of the cat family, among which are the jaguar, puma or cougar and the ocelot. A small fox or fox-like dog lives on the prairies. A species of Procyon is described as a crab-eating racoon, and the two species of coati (Nasua) also belong with the racoons. The janauhy (Icticyon) or caclzorro de matto com bines the characteristics of a dog, badger, martin and beaver. Other Amazonian carnivores are the papa-mel (Galictis), kinkajou, otter, grison or ferret (Grisonia) and weasel (Putorius), the latter rather rare.
This region is particularly rich in rodents, the largest rodent species in the world, the capybara, being indigenous and common along the stream banks. It is said to attain a length of over aft. and a weight of over 5o kilograms. Other common rodents are the paca (Coelogenys), cutia or agouti (Dasyprocta), sauia or spiny rat, toro (Loncheres), several species of squirrels, rats and mice, and two species of porcupines. Paca meat is highly esteemed, but the capybara and a number of other forms are frequently used as food.
The largest animal is the anta or tapir, which makes its home in the giant cane-brakes along the streams. There are two species of peccary (Dicotyles). One of these, the queixada or porco de matto, lives in bands of too or more and twice invaded the small city of Obidos.
Five species of armadillos or tatu occur, both the giant and the pygmy species being represented. The former reaches a length of 3 feet. Of the three species of anteaters, two of them are tree dwelling, while the giant ant-eater or tamandua bandeira is generally a prairie animal. The two sloths are both forest forms, and one species lives largely on cecropia leaves, while the other has a more varied plant diet of foliage and fruit. The flesh of the latter recalls mutton.
Four species of deer are found on the prairies and neighbouring woods, and thousands of hides are exported. The three species of opossums range in size from the mucura, as large as a cat, to the mouse-dimensioned mucura cbichica with large eyes.
Bats by the million fan the Amazon night air, and represent numerous species and genera. Among them are the blood-sucking vampires (Dysopes, Phyllostoma), although these are by no means as dangerous as we are led to infer from travellers' tales.
The sea-cow or manatee is common in the lakes and hunted for its meat, which resembles pork. It is one of the most peculiar mammals of the region, with its cow-like face, its small eyes and its two large, well-developed pectoral mammae. Fresh-water dolphins of several species disport themselves in small schools.
Humming-birds are not so numerous at low altitudes in the main valley, but in the Andean headwaters region, especially in the bush country, they are a striking feature of the scene. One of the common birds is the Clay-John or ovenbird, with its peculiar oven-shaped nest on a forked prairie-tree limb. Egrets roost beside the campos lakes. Muscovy and teal ducks swim about in quiet lagoons. In the marshes, the jabiru or great South American marabou stork is not an infrequent sight. There are two species of geese. Herons, gulls, anhingas, cormorants, roseate spoonbills, scarlet ibises and jacanas are among the com mon water-birds. Gorgeous trogons, cock-of-the-rocks, cotingas and tanagers are natives, while on the prairies between the Mamore and the Beni rivers the rhea or South American ostrich is found.
One of the principal food supplies of the valley is the tartaruga turtle (Podocnemis). The swamps, sluggish streams and lakes usually contain one or more species of cayman. Lizards of vari ous sizes and colours dart back and forth across the trails. The snakes, relatively speaking, are not numerous, but representatives of both poisonous groups occur (Lachesis, Crotalus, Cophais, Elaps). The constrictors (Eunectes, Epicrates) reach huge pro portions, 18 to 2of t. not being rare. Snakes, however, are not a prominent feature of Amazon life ; perhaps the poisonous indi viduals observed are not more than one in 20 or 3o. One of the deadly Lachesis species (rattlesnake) is considered a royal dish by the Indians. The frogs and toads abound in vivid contrasts both in shape and colouring; they are very noisy at night, and are not as edible as temperate-zone frogs.
The fish species of the Amazon have been estimated to be any where from 521 to 1,800 or 2,000, but only a few of them are of economic importance. Of these, the pirarucu is the most sought after. The scales of one species are utilized for making artificial flowers. In the half-covered forest pools, the electric eel is at home. Most of the streams are well stocked with the blood thirsty piranha (Serrasalmo). Giant catfish are common and sting rays are present.
As to insects, their name in Amazonia is legion. Countless multitudes of ants work night and day. Their work varies with the species. Some are farmers like the saubas or leaf-cutters, others are always on marauding expeditions, while still others live in certain types of trees, and sting as well as bite. Termites, the so-called "white ants," abound and cause great destruction to nearly anything of wood. Fireflies with yellow, red and green lights make toy fairylands of little brooks, while a host of other insects by various devices, depending on the region, turn a para dise into purgatory. The bees are stingless, but hornets and wasps are plentiful. Titanus giganteus, the largest beetle known (5-6in. long), is native. The larvae of some of the palm-beetles are relished when fried. Cockroaches are ever-present. Part of the afternoon and evening music is furnished by several species of cicadas, one of which sounds like a shrill steam whistle. Centi pedes, scorpions, ticks, red bugs and giant spiders are often met with. Finally there are the moths and butterflies, hundreds of kinds and thousands of individuals, in marvellous assortments of brilliant colours and patterns. Within an hour's walk of Para, 700 species have been collected, as compared with 321 species for all Europe. Around Ega, Bates collected 7,00o species of insects, of which S5o were species of butterflies.
BIBLIOGRAPHY.-Paul Le Cointe, L'Amazonie bresilienne, Le paysBibliography.-Paul Le Cointe, L'Amazonie bresilienne, Le pays- ses habitants, ses ressources, notes et statistiques jusqu'en 1920; H. W. Bates, Naturalist on the River Amazon; Richard Spruce, Notes of a Botanist on the Amazon and the Andes; A. R. Wallace, Narrative of Travels on the Amazon, etc.; K. F. P. von Martius, A. W. Eichler and I. Urban, Flora Brasiliensis; James Orton, The Andes and the Amazon; O. E. White, The Amazon Valley, Naturalists' Guide to the Americas. Theodore Roosevelt, Through the Brazilian Wilderness (1914) ; H. M. Tomlinson, The Sea and the Jungle (1912) ; J. F. Woodroffe, The Upper Reaches of the Amazon (1914) ; and Recenseamento do Brazil (1922) by the director general of statistics, Rio de Janeiro. (O. E. W.)