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19-568: The river originates in the central part of the island, on the southern side of the Maoke Mountains (Digul or Star Mountains), which rise above sea level at 4,700 m. After leaving the mountainous section, it cuts througth lowland swamps in a south-southwest direction and then flows by delta into the Arafura Sea , across Dolak Island . Its marshy, swampy floodplain is lined with reed beds. As there are no accessible and developed roads in

38-652: A very winding course over flat land to the sea. The swamplands upstream were known by the name " Boven-Digoel " (Above the Digul, in Dutch) and hosted a penal colony at Tanahmerah (Red Earth) in the early 20th century, when Indonesia was a colony of Holland . As a result of the abortive 1926 revolt by the Communist Party of Indonesia (PKI), the Dutch exiled 823 of the most troublesome revolutionaries here. Rising on

57-667: Is a mountain range in the province of Central Papua and Highland Papua . It extends over 692 km and is composed of the Sudirman and Jayawijaya ranges. It is part of the larger New Guinea Highlands or Central Cordillera. Although Maoke means 'snow' in the local language, the glacier on Puncak Trikora in the Maoke Mountains disappeared completely some time between 1939 and 1962. 4°00′S 138°00′E  /  4.000°S 138.000°E  / -4.000; 138.000 This Central Papua location article

76-439: Is a stub . You can help Misplaced Pages by expanding it . This Highland Papua location article is a stub . You can help Misplaced Pages by expanding it . Mountain range A mountain range or hill range is a series of mountains or hills arranged in a line and connected by high ground. A mountain system or mountain belt is a group of mountain ranges with similarity in form, structure, and alignment that have arisen from

95-538: Is at work while the mountains are being uplifted until the mountains are reduced to low hills and plains. The early Cenozoic uplift of the Rocky Mountains of Colorado provides an example. As the uplift was occurring some 10,000 feet (3,000 m) of mostly Mesozoic sedimentary strata were removed by erosion over the core of the mountain range and spread as sand and clays across the Great Plains to

114-462: Is changing rapidly from year to year (new channels and delta branches) due to the high sedimentation process (clay deposits, sedimentary silt) on the banks. The delta is rich in fauna and, although navigable, very sparsely populated. The Digul catchment has a rich and diverse fauna. Around 100 endemic species are found here ( Paradisaea apoda , Ptilinopus perlatus , Chelodina novaeguineae , Centropus violaceus , Alcedinidae , etc.). The mud islands of

133-865: The Alpide belt . The Pacific Ring of Fire includes the Andes of South America, extends through the North American Cordillera , the Aleutian Range , on through Kamchatka Peninsula , Japan , Taiwan , the Philippines , Papua New Guinea , to New Zealand . The Andes is 7,000 kilometres (4,350 mi) long and is often considered the world's longest mountain system. The Alpide belt stretches 15,000 km across southern Eurasia , from Java in Maritime Southeast Asia to

152-551: The Annamite Range . If the definition of a mountain range is stretched to include underwater mountains, then the Ocean Ridge forms the longest continuous mountain system on Earth, with a length of 65,000 kilometres (40,400 mi). The position of mountain ranges influences climate, such as rain or snow. When air masses move up and over mountains, the air cools, producing orographic precipitation (rain or snow). As

171-804: The Iberian Peninsula in Western Europe , including the ranges of the Himalayas , Karakoram , Hindu Kush , Alborz , Caucasus , and the Alps . The Himalayas contain the highest mountains in the world, including Mount Everest , which is 8,848 metres (29,029 ft) high. Mountain ranges outside these two systems include the Arctic Cordillera , Appalachians , Great Dividing Range , East Siberians , Altais , Scandinavians , Qinling , Western Ghats , Vindhyas , Byrrangas , and

190-627: The air descends on the leeward side, it warms again (following the adiabatic lapse rate ) and is drier, having been stripped of much of its moisture. Often, a rain shadow will affect the leeward side of a range. As a consequence, large mountain ranges, such as the Andes, compartmentalize continents into distinct climate regions . Mountain ranges are constantly subjected to erosional forces which work to tear them down. The basins adjacent to an eroding mountain range are then filled with sediments that are buried and turned into sedimentary rock . Erosion

209-524: The area is 22 °C. The warmest month is April, when the average temperature is around 24 °C, and the coldest is June, at 20°C. The average annual rainfall is 3,072 mm. The wettest month is January, with an average of 464 mm rainfall, and the driest is July, with 28 mm rainfall. The average rainfall for the whole catchment area between 2002 and 2011 was 3,522 mm. Its delta is a relatively new tidal delta in development with wide and deep delta branches and channels. The intermittent tides reach 5–7 metres. The delta

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228-413: The area, the river is still the only transport route across the marshes to the fertile hills and mountains in the interior of the island. It is navigable by larger boats from Tanahmerah (320 km) and by smaller boats from the foot of the mountains. This swampy navigable stretch is often referred to as Boven-Digul . Its length as the crow flies from its source to its mouth is relatively short, but it follows

247-472: The delta are covered with marsh and forest vegetation. The dominant species are mangrove ( Avicenia alba , Rhizophora apiculata ), mahogany ( Xylocarpus moluccensis ), nipa palm ( Nypa fruticans ), marsh plant ( Bruguiera cylindrica ) and their hybrids ( Rhizphora mucronata ). *Monthly flow (m/s): delta The main tributaries from the mouth: tributary tributary (km) (km) (m/s) Period: 1971–2000 Maoke Mountains The Maoke Mountains

266-485: The east. This mass of rock was removed as the range was actively undergoing uplift. The removal of such a mass from the core of the range most likely caused further uplift as the region adjusted isostatically in response to the removed weight. Rivers are traditionally believed to be the principal cause of mountain range erosion, by cutting into bedrock and transporting sediment. Computer simulation has shown that as mountain belts change from tectonically active to inactive,

285-627: The rate of erosion drops because there are fewer abrasive particles in the water and fewer landslides. Mountains on other planets and natural satellites of the Solar System, including the Moon , are often isolated and formed mainly by processes such as impacts, though there are examples of mountain ranges (or "Montes") somewhat similar to those on Earth. Saturn 's moon Titan and Pluto , in particular, exhibit large mountain ranges in chains composed mainly of ices rather than rock. Examples include

304-502: The same cause, usually an orogeny . Mountain ranges are formed by a variety of geological processes, but most of the significant ones on Earth are the result of plate tectonics . Mountain ranges are also found on many planetary mass objects in the Solar System and are likely a feature of most terrestrial planets . Mountain ranges are usually segmented by highlands or mountain passes and valleys . Individual mountains within

323-531: The same mountain range do not necessarily have the same geologic structure or petrology . They may be a mix of different orogenic expressions and terranes , for example thrust sheets , uplifted blocks , fold mountains, and volcanic landforms resulting in a variety of rock types . Most geologically young mountain ranges on the Earth's land surface are associated with either the Pacific Ring of Fire or

342-501: The southern slopes of Maoke Mountains , the Digul flows first south and then west to empty into the Arafura Sea . For much of its length, it travels across a low region of extensive swamps and creates a delta near Dolak (Yos Sudarso Island, formerly Frederik Hendrik) Island. The river has a length of 853 km (530 mi) and is navigable as far as Tanahmerah . Together with the Mappi , which joins its northernmost delta, it collects

361-533: The waters of an area of about 45,000 square kilometres. The river flows in the southern area of Papua with predominantly tropical monsoon climate (designated as Am in the Köppen-Geiger climate classification) and tropical rainforest (designated as Af in the Köppen-Geiger climate classification) transitional type, with an annual rainfall of 3,500–4,000 mm. The annual average temperature in

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