Online Encyclopedia
Search over 40,000 articles from the original, classic Encyclopedia Britannica, 11th Edition.
AMAZON BASIN
Online EncyclopediaEncyclopedia Home :: ALM-ANC
del.icio.us it!
|
See also:AMAZON See also:BASIN Mo,lelll •e la terra • _= See also:English See also:Miles \`` ((i i ' 0 50 See also:roc zoo 3w 400 rA t P • _ ;_~ o 'er • Fn° See also:Longitude See also:West 70° of See also:Greenwich °so "~/ , , bo° So° equal to that of See also:France and See also:Spain. The See also:waters find their way to the falls of the See also:Madeira by many See also:great See also:rivers, the See also:principal of which, if we enumerate them from See also:east to west, are the Guapore or Itenez, the Baures and Blanco, the Itonama or See also:San See also:Miguel, the See also:Mamore, Beni, and Mayutata or Madre de Dios, all of which are reinforced by numerous secondary but powerful affluents. The Guapore presents many difficulties to continuous See also:navigation; the Baures and Itonama offer hundreds of miles of navigable waters through beautiful plains; the Mamore has been sounded by the writer in the driest See also:month of the See also:year for a distance of 500 M. above Guajara-Merim, who found never less than from Io to 30 ft. of See also:water, with a current of from 1 to 3 M. an See also:hour. Its Rio Grande See also:branch, explored under the writer's instructions, was found navigable for See also:craft See also:drawing 3 ft. of water to within 30 M. of See also:Santa Cruz de la Sierra—a level sandy See also:plain intervening. The Grande is a See also:river of enormous length, rising in a great valley of the See also:Andes between the important cities of See also:Sucre and See also:Cochabamba, and having its upper waters in See also:close See also:touch with those of the Pilcomayo branch of the river See also:Paraguay. It makes a See also:long See also:curve through the mountains, and, after a course of about Boo m., joins the Mamore near 15° S. See also:lat. The Chapare, Secure and Chimore, tributaries of the Mamore, are navigable for launches up to the See also:base of the mountains, to within 130 M. of Cochabamba. The Beni has a 12-ft. fall 18 m. above its mouth called "La Esperanza "; beyond this, it is navigable for 217 m. to the See also:port of Reyes for launches in the dry See also:season and larger craft in the wet one. The extreme source of the Beni is the little river La Paz, which rises in the inter-Andean region, a few miles See also:south-east of See also:Lake Titicaca, and flows as a rivulet through the Bolivian See also:city of La Paz. From this point to Reyes the river is a torrent. The principal affluent of the Beni, and one which exceeds it in See also:volume, enters it 120 M. above its mouth, and is known to the See also:Indians along its See also:banks as the Mayutata, but the Peruvians See also:call it the Madre de Dios. Its ramifications drain the slopes of the Andes between 12° and 15° of See also:latitude. It is navigable in the wet season to within 18o m. of See also:Cuzco. Its upper waters are separated by only a See also:short transitable See also:canoe See also:portage of 7 M. in a straight See also:line from those of the Ucayali. The portage on the eastern See also:side terminates at the Cashpajali river 22 M. above its junction with the Manu. For the first 13 m. it is navigable all the year for craft drawing 18 in. of water, but the remaining 9 m. See also:present many obstacles to navigation. At the Manu junction the See also:elevation above See also:sea-level is 1070 ft., the river width 300 ft., See also:depth 8 ft., current 14 m. per hour. The See also:general direction of the Manu is south-east for 158 m. as far as the Pilcopata river, where under the name of Madre de Dios it continues with a flow of 22,000 cubic metres per See also:minute. Here its elevation is 718 ft. above the sea and its width Soo ft. During the above course of 158 m. the Manu receives 135 large and small affluents. Although the inclination of its See also:bed is not great, the obstacles to See also:free navigation are abundant, and consist of enormous trees and masses of See also:tree-trunks which have filled the river during the See also:period of freshets. From the See also:time it receives the Manu, the Madre de Dios carries its immense volume of waters 485 M. to the Beni over the extremely easy slope of a vast and fertile plain. Its banks are See also:low, its bottom pebbly. A greater See also:part of its course is filled with large and small islands some 63 in number. Its See also:average width is about 1500 ft. Below the mouth of the Tambopata, the flow is estimated at 191,250 cubic metres per. minute. The average current is 21 M. per hour. There are two important rapids and one See also:cataract on the See also:lower 300 M. of the river. The Mayutata receives three principal tributaries from the south—the Tambopata, Inambari and Pilcopata. The Peruvian See also:government has sought to open a See also:trade route between the Rio Ucayali and the See also:rich See also:rubber districts of the Mayutata. All of the upper branches of the river Madeira find their way to the falls across the open, almost level 1VIojos and Beni plains, 35,000 sq. m. of which are yearly flooded to an average depth of about 3 ft. for a period of from three to four months. They See also:rival if they do not exceed in fertility the valley of the See also:Nile, and are the healthiest and most inviting agricultural and grazing region of the basin of the Amazon. The PURUS, a very sluggish river, enters the Amazon west of the Madeira, which it See also:parallels as far .south as the falls of the latter stream. It runs through a continuous See also:forest at the bottom of the great depression lying between the Madeira river, which skirts the edge of the Brazilian See also:sandstone See also:plateau, and the Ucayali which hugs the base of the Andes. One of its marked features is the five parallel furos' which from the See also:north-west at almost See also:regular intervals the Amazon sends to the Purus; the most south-See also:westerly one being about 15o M. above the mouth of the latter river. They cut a great See also:area of very low-lying See also:country into five islands. Farther down the Purus to the right three smaller furos also connect it with the Amazon. Chandless found its elevation above sea-level to be only 107 ft. 590 M. from its mouth. It is one of the most crooked streams in the See also:world, and its length in a straight line is less than See also:half that by its curves. It is practically only a drainage ditch for the half-submerged, lake-flooded See also:district it traverses. Its width is very See also:uniform for r000 m. up, and for Boo m. its depth is never less than 45 ft. It is navigable by steamers for 1648 m. as far as the little stream, the Curumaha, but only by See also:light-draft craft. Chandless ascended it 1866 m. At 1792 M. it forks into two small streams. Occasionally a cliff touches the river, but in general the lands are subject to yearly inundations throughout its course, the river rising at times above 50 ft., the numerous lakes to the right and See also:left serving as reservoirs. Its See also:main tributary, the Aquiry or See also:Acre, enters from the right about 1104 m. from the Amazon. Its See also:sources are near those of the Mayutata. It is navigable for a period of about five months of the year, when the Purus valley is inundated; and, for the remaining seven months, only canoes can ascend it sufficiently high to communicate overland with the settlements in the great indiarubber districts of the Mayutata and lower Beni; thus these regions are forced to seek a canoe outlet for their rich products by the very dangerous, costly and laborious route of the falls of the Madeira. The Juaua is the next great See also:southern affluent of the Amazon west of the Purfis, sharing with this the bottom of the immense inland Amazon depression, and having all the characteristics of the Purus as regards curvature, sluggishness and general features of the low, half-flooded forest country it traverses. It rises among the Ucayali See also:highlands, and is navigable and unobstructed for a distance of 1133 M. above its junction with the Amazon. The JAVARY, the boundary line between See also:Brazil and See also:Peru, is another Amazon tributary of importance. It is supposed to be navigable by canoe for 900 M. above its mouth to its sources among the Ucayali highlands, but only z6o have been found suitable for See also:steam navigation. The Brazilian Boundary See also:Commission ascended it in 1866 to the junction of the Shino with its Jaquirana branch. The country it traverses in its extremely sinuous course is very level, similar in See also:character to that of the Jurua, and is a fostered See also:wilderness occupied by a few See also:savage hordes. The UCAYALI, which rises only about 7o M. north of Lake Titicaca, is the most interesting branch of the Amazon next to the Madeira. The Ucayali was first called the San Miguel, then the Ucayali, Ucayare, Poro, Apu-Poro, Cocama and Rio de Cuzco. Peru has fitted out many costly and ably-conducted expeditions to explore it. One of them (1867) claimed to have reached within 240 M. of See also:Lima, and the littlesteamer " Napo " forced its way up the violent currents for 77 M. above the junction with the Pachitea river as far as the river Tambo, 77o m. from ' A furo is a natural canal—sometimes merely a deviation from the main channel, which it ultimately rejoins, sometimes a connexion across low See also:flat country between two entirely See also:separate streams.the confluence of the Ucayali with the Amazon. The "-Napo " then succeeded in ascending the Urubamba branch of the Ucayali 35 M. above its See also:union with the Tambo, to a point 200 M. north of Cuzco. The See also:remainder of the Urubamba, as shown by See also:Bosquet in 1806 and See also:Castelnau in 1846, is interrupted by cascades, reefs and numberless other obstacles to navigation. Senor Torres, who explored the See also:Alto Ucayali fbr the Peruvian government, gives it a length of 186 m., counting from the mouth of the Pachitea to the junction of the Tambo and Urubamba. Its width varies from 1300 to 4000 ft., due to the great number of islands. The current runs from 3 to 4 M. an hour, and a channel from 6o to 15o ft. wide can always be found with a minimum depth of 5 ft. There are five See also:bad passes, due to the See also:accumulation of trees and rafts of See also:timber. Sometimes enormous rocks have fallen from the mountains and spread over the river-bed causing huge whirlpools. " No greater difficulties present themselves to navigation by 10-See also:knot steamers drawing 4, ft. of water." The TAMBO, which rises in the Vilcanota knot of mountains south of Cuzco, is a' torrential stream valueless for commercial purposes. The banks of the Ucayali for 500 M. Up are low, and in the See also:rainy season extensively inundated. The HUALLAGA (also known as - the Guallaga and Rio de los Motilones), which joins the Amazon to the west of the Ucayali, rises high among the mountains, in about lo° 40' S. lat., on the See also:northern slopes of the celebrated Cerro de Pasco. For nearly its. entire length it is an impetuous torrent See also:running through a See also:succession of See also:gorges. It has See also:forty-two rapids, its last obstruction being the Pongo de Aguirre, so called from the traitor Aguirre who passed there. To this point, 140 M. from the Amazon, the Huallaga can be ascended by large river steamers. Between the Huallaga and the Ucayali lies the famous " See also:Pampa del See also:Sacramento," a level region of stoneless alluvial lands covered with thick, dark forests, first entered by the missionaries in 1726. It is about 300 M. long, from north to south, and varies in width from 40 to 100 M. Many streams, navigable for canoes, penetrate this region from the Ucayali and the Huallaga. It is still occupied by savage tribes. The river MARANON rises about roo m. to the north-east of Lima. It flows through a deeply-eroded Andean valley in a north-west direction, along the eastern base of the See also:Cordillera of the Andes, as far as 5° 36' S. lat.; then it makes a great See also:bend to the north-east, and with irresistible See also:power cuts through the inland Andes,, until at the Pongo de Manseriche2 it victoriously breaks away from the mountains to flow onwards through the plains under the name of the Amazon. Barred by reefs, and full of rapids and impetuous currents, it cannot become a commercial See also:avenue. At the point where it makes its great bend the river Chinchipe pours into it from southern See also:Ecuador. Just below this the mountains close in on either side of the Maranon, forming narrows or pongos for a length of 35 m., where, besides numerous whirlpools, there are no less than See also:thirty-five formidable rapids, the See also:series concluding with three cataracts just before reaching the river Imasa or Chunchunga, near the mouth of which La Condamine embarked in the 18th See also:century to descend the Amazon. - Here the general level of the country begins to decrease in elevation, with only a few See also:mountain spurs, which from time to time push as far as the river and See also:form pongos of See also:minor importance and less dangerous to descend. Finally, after passing the narrows of Guaracayo, the cerros gradually disappear, and for a distance of about 20 M. the river is full of islands, and there is nothing visible from its low banks but an immense forest-covered plain. But the last barrier has yet to be passed, the Pongo de Manseriche, 3 M. long, just below the mouth of the Rio See also:Santiago, and between it and the old abandoned missionary station of Borja, in 38° 30' S. lat. and 77° 30' 40" W. long. According to See also:Captain Carbajal, who descended it in the little 2 Pongo is a corruption of the See also:Quichua puncu and the See also:Aymara ponco, meaning a See also:door. The Pongo de Manseriche was first named' Maranon, then Santiago, and later Manseric, afterwards Mansariche and Manseriche, owing to the great See also:numbers of parrakeets found on the rocks there. steamer " Napo " in 1868, it is a vast See also:rent in the Andes about 2000 ft. deep, narrowing in places to a width of only See also:loo ft., the precipices " seeming to close in at the See also:top." Through this dark See also:canon the Maranon leaps along, at times, at the See also:rate of 12 M. an hour.' The Pongo de Manseriche was first discovered by the Adelantado See also:Joan de Salinas. He fitted out an expedition at Loxa in Ecuador, descended the Rio Santiago to the Maranon, passed through the perilous Pongo in 1557 and invaded the country of the Maynas Indians. Later, the missionaries of See also:Cuenca and See also:Quito established many See also:missions in the Pais de los Maynas, and made extensive use of the Pongo de Manseriche as an avenue of communication with their several convents on the Andean plateau. According to their accounts, the huge rent in the Andes, the Pongo, is about five or six m. long, and in places not more than 8o ft. wide, and is a frightful series of torrents and whirlpools interspersed with rocks. There is an See also:ancient tradition of the savages of the vicinity that one of their gods descending the Maranon and another ascending the Amazon to communicate with him, they opened the pass called the Pongo de Manseriche. From the northern slope of its basin the Amazon receives many tributaries, but their combined volume of water is not nearly so great as that contributed to the See also:parent stream by its affluents from the south. That part of Brazil lying between the Amazon and See also:French, Dutch and See also:British See also:Guiana, and bounded on the west by the Rio See also:Negro, is known as Brazilian Guiana. It is the southern See also:watershed of a tortuous, low See also:chain of mountains running, roughly, east and west. Their northern slope, which is occupied by the three Guianas first named, is saturated and river-torn; but their southern one, Brazilian Guiana, is in general thirsty and semi-barren, and the driest region of the Amazon valley. It is an area which has been left almost in the undisturbed See also:possession of nomadic See also:Indian tribes, whose scanty numbers find it difficult to solve the See also:food problem. From the divot-limn aquarum between French Guiana and Brazil, known as the Tumuc-humac range of highlands, two minor streams, the Yary and the Parou, reach the Amazon across the intervening broken and barren tableland. They are full of rapids and reefs. The TROMBETAS is the first river of importance we meet on the northern side as we ascend the Amazon. Its confluence with this is just above the See also:town of Obidos. It has its sources in the Guiana highlands, but its long course is frequently interrupted by violent currents, rocky barriers, and rapids. The inferior See also:zone of the river, as far up as the first fall, the Porteira, has but little broken water and is low and swampy; but above the long series of cataracts and rapids the character and aspect of the valley completely See also:change, and the See also:climate is much better. The river is navigable for 135 M. above its mouth. The NEGRO, the great northern tributary of the Amazon, has its sources along the watershed between the See also:Orinoco and the Amazon basins, and also connects with the Orinoco by way of the Casiquiare See also:canal. Its main affluent is the Uaupes, which disputes with the headwaters of the Guaviari branch of the Orinoco the drainage of the eastern slope of the " See also:oriental " Andes of See also:Colombia. The Negro is navigable for 450 M. above its mouth for 4 ft. of water in the dry season, but it has many sandbanks and minor difficulties. In the wet season, it overflows the country far and wide, sometimes to a breadth of 20 m., for long distances, and for 400 M. Up, as far as Santa See also:Isabella, is a succession of lagoons, full of long islands and intricate channels, and the slope of the country is so See also:gentle that the river has almost no current. But just before reaching the Uaupes there is a long series of reefs, over which it violently flows in cataracts, rapids and whirlpools. The Uaupes is full of similar obstacles, some fifty rapids barring its navigation, although a long stretch of its upper course is said to be free from them, and to flow gently through a forested country. Despite the impediments, canoes ascend this stream to the Andes. ' One of the most daring deeds of exploration ever known in South See also:America was done by the engineer A. Wertheman: He fitted out three rafts, in See also:August 1870, and descended this whole series of rapids and cascades from the Rio Chinchipe to Borja. The See also:Branco is the principal affluent of the Negro from the north; it is enriched by many streams from the sierras which separate See also:Venezuela and British Guiana from Brazil. Its two upper main tributaries are the Urariquira and the Takutu. The latter almost links its sources with those of the See also:Essequibo. The Branco flows nearly south, and finds its way into the Negro through several channels and a chain of lagoons similar to those of the latter river. It is 350 m. long, up-to its Urariquira confluence. It has numerous islands, and, 235 m. above its mouth, it is broken by a bad series of rapids. Additional information and CommentsThere are no comments yet for this article.
» Add information or comments to this article.
Please link directly to this article:
Highlight the code below, right click, and select "copy." Then paste it into your website, email, or other HTML. Site content, images, and layout Copyright © 2006 - Net Industries, worldwide. |
|
|
[back] AMAZON |
[next] AMAZONAS |