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\\nToday we\\u2019re going to the Mountains of the\\nMoon \\u2013 but not those on the moon itself. We\\u2019re going to central Africa.
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\\nThere isn\\u2019t really a mountain range specifically named the\\nMountains of the Moon. The ancients, from Egyptians to Greeks, imagined or\\nheard rumor of a mountain range in east-central Africa that was the source of\\nthe river Nile. In the 18^th and 19^th centuries,\\nexplorations of the upper Nile found the sources of the Blue Nile, White Nile,\\nand Victoria Nile and identified the Mountains of the Moon with peaks in\\nEthiopia as well as 1500 kilometers away in what is now Uganda. Today, the\\nrange most closely identified with the Mountains of the Moon is the Rwenzori\\nMountains at the common corner of Uganda, the Democratic Republic of Congo, and\\nRwanda.
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\\nThis location is within the western branch of the East\\nAfrican Rift system, an 8,000-kilometer-long break in the earth\\u2019s crust that\\u2019s\\nin the slow process of tearing a long strip of eastern Africa away from the\\nmain continent. We talked about it in the episode for December 16, 2014.
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\\nThe long linear rifts in east Africa are grabens, narrow\\ndown-faulted troughs that result from the pulling apart and breaking of the\\ncontinental crust. The rifts are famously filled in places by long, linear rift\\nlakes including Tanganyika, Malawi, Turkana, and many smaller lakes.
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Virunga Mountains (2007 false-color Landsat image, annotated by Per Andersson : Source)

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\\nWhen rifting breaks the continental crust, pressure can be\\nreleased at depth so that the hot material there can melt and rise to the\\nsurface as volcanoes. In the Rwenzori, that\\u2019s exactly what has happened. The Virunga\\nvolcanoes, a bit redundant since the name Virunga comes from a word meaning\\nvolcanoes, dominate the Rwenzori, with at least eight peaks over 10,000 feet\\nhigh, and two that approach or exceed 4,500 meters, 15,000 feet above sea\\nlevel. They rise dramatically above the floors of the adjacent valleys and\\nlakes which lie about 1400 meters above sea level.
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\\nThese are active volcanoes, although several would be\\nclassified as dormant, since their last dated eruptions were on the order of 100,000\\nto a half-million years ago. But two, Nyiragongo and Nyamuragira, have erupted\\nas recently as 2002, when lava from Nyiragongo covered part of the airport\\nrunway at the town of Goma, and in 2011 with continuing lava lake activity.\\nNyiragongo has erupted at least 34 times since 1882. The volcanic rocks of\\nthese and the older volcanoes fill the rift enough that the flow of rivers and\\npositions of lakes have changed over geologic time.
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\\nLake Kivu, the rift lake just south of the volcanoes, once\\ndrained north to Lake Edward and ultimately to the Nile River, but the\\nvolcanism blocked the outlet and now Lake Kivu drains southward into Lake\\nTanganyika. Local legends, recounted by Dorothy Vitaliano in her book on\\nGeomythology, Legends of the Earth (Indiana University Press, 1973), tell the\\nstory of demigods who lived in the various Virunga volcanoes. As demigods do,\\nthese guys had frequent arguments and battles, which are probably the folklore\\nequivalent of actual volcanic eruptions. The stories accurately reflect \\u2013\\nwhether through observation or happenstance \\u2013 the east to west migration of\\nvolcanic activity in the range.
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\\nThe gases associated with the volcanic activity seep into\\nthe waters of Lake Kivu, which has high concentrations of dissolved carbon\\ndioxide and methane. Generally the gases are contained in the deeper water\\nunder pressure \\u2013 Lake Kivu is the world\\u2019s 18^th deepest lake, at 475\\nmeters, more than 1,500 feet. But sometimes lakes experience overturns, with\\nthe deeper waters flipping to the surface. When gases are dissolved in the\\nwater and the pressure reduces, they can abruptly come out of solution like\\nopening a carbonated beverage bottle. This happened catastrophically at Lake\\nNyos in Cameroon in 1986, asphyxiating 1700 people and thousands of cattle and\\nother livestock. The possibility that Lake Kivu could do the same thing is a\\nreal threat to about two million people.
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\\nThe critically endangered mountain gorilla lives in the\\nVirunga Mountains, which also holds the research institute founded by Dian\\nFossey.

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