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transcript
8/13/2019 Africa Great Rift Valley Art
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L
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Lake
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Lake George
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SEMULIKI
NAT. PARK
RWENZORI MTS.
NAT. PARK
VIRUNGA
NATIONAL
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MURCHISON
FALLS
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NSUMBU
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QUEEN
ELIZABETH
NATIONALPARK
MAHALE MTS.
NATIONAL
PARK
KIBALENATIONALPARK
BWINDI IMPENETRABLE
NAT. PARK
GOMBE STREAM
NAT. PARK
MGAHINGA
GORILLA
NAT. PARK
VOLCANS NAT. PARK
A
A
Goma
Bunia
Uvira
Uvinza
Kigoma
Kigali
Huye(Butare)
Bukavu
Butembo
Rubavu(Gisenyi)
Muyinga
Bujumbura
Musanze (Ruhengeri)
RWANDA
TANZANIA
UGANDA
DEMOCRATIC
REPUBLIC
OF THE
CONGO
BURUNDI
DEMOCRATIC
REPUBLIC
OF THE
CONGO
ZAMBIA
TANZANIA
UGANDA
BURUNDI
RWANDA
TANZANIA
ZAMBIA
BURUNDI
RWANDA
UGANDA
SOUTHSUDAN
DEMOCRATIC
REPUBLIC
OFTHE
CONGO
Lowla nd
Forest
Lowl and
Forest
FloodedGrassland
FloodedGrassland
FloodedGrassland
ThicketFlooded
Grassland
The western arm of Africas Great Rift Valleythe Albertine Riftembraces such
rich and varied habitats that its wildlife diversity is unparalleled on the continent.
With deep freshwater lakes filling the valleys spine (map, far left), the Albertine spans
mountains, marshes, savannas, and active volcanoes. The geologic forces that created
this rift valley are still in motion, most visibly at its center, around Lake Kivu (below).
TODAY
10 MILLIONYEARS AGO
Tectonicplatesbegin to moveapart asmagmarises. A shallowvalley forms, with alowescarp-ment, orridge, along afault line.Lavaoozesup through fissuresand coolsinto sheetsof rock.
7.5 MILLIONYEARS AGO
More magmarises asthe landcontinuestostretchand fracture.Volcanicconesbegin to dotthe valley. Faulting causesthewest side ofthe valley to sink,heightening the escarpment.
3 MILLIONYEARS AGO
The widening rift valley sinksfurther, creating an escarpmenton the east. Streamsflowing fromthe western highlandsfillan earlyLake Kivu. Erupting volcanoeswillform the VirungaMountains.
Splitting a ContinentAfricasGreat Rift Valley followsthe edgesof tectonic
platesthat merged more than abillion years ago. Now
the platesare separating, or rifting, along those seams.
The Arabian plate wasthe first to split off, starting 30 to
25 million yearsago. In another30 million years, riftingmay cleave the Somalian plate fromthe main continent
and detach the block called the Tanzaniacraton.
The Albertine ArkTheAlbertineRift cradlesmorethan 850speciesfound
nowhereelseincludingtherare mountaingorilla(about
780remain) andthe venomousGreatLakesbush viper.
There are familiarfacestoo: More than 50 percent
ofthecontinentsbirdspeciesandalmost40percentof
itsmammal specieslivehere. Theillustratedscenesat
bottomhighlightfour vitalAlbertineecosystems.
A MONTANE FOREST B ALPINE MOORLAND
The Great
C LAKE AND WETLAND D SAVANNA-FOREST MOSAIC
Covering the lowerslopes ofmountains and the high-landsflanking the valley, thisecosystemholds the riftsgreatest number of endemic species. Flamboyant birdsand chameleonsand 11 speciesofmonkeysshare theforest with the web-toed Ruwenzoriotter shrew, aboutafoot long, which catchescrabs and insectsin streams.
Ataltitudesabove10,000 feet,themisty RwenzoriMountainsandthe volcanicVirungachainshelterother-worldlyplantsheathersas tallastrees andtoweringlobelias.Thickfur warmsthetree hyrax,adistant relativeofthe elephant.Twoendangeredprimates,themountaingorillaandthe goldenmonkey,survivehere.
Papyrusis the sole perch ofthe red-breasted papyrusgonolek. Along with otherwetland vegetation, papyrusfrondsform supportive matsfor aquaticantelope calledsitatungas. The Congo clawlessotterfishes here andalso digs for giant earthworms in pockets of swampyforest clearingsscattered about the rift.
Two rainy seasonsayear bring abundant grassfor thesavannas grazing topi and Uganda kobprey for the toppredators,lions,and forscavengingvulturesand eagles.As elephants push over trees while feeding on branchesand leaves, grassland expands. Naturalfiresfrequentlysweep through, priming the savannaforregeneration.
DYNAMICS OF LIFE IN THE ALBERTINE RIFT
Rift Valley
Blue-headedsunbird
Ruwenzoriduiker
Shoebillstork
Hippopotamus Africanlion
Africanelephant
Mountaingorilla
Giantlobelia
Parrotimpatiens
Red hotpoker flower
Uganda giantcycad
Great Lakesbush viper
Extreme variation in altitude and
climate contributesto the Albertinesbiodiversity. This elevation profile ofhabitats, with theirtypicalplantsandanimals, tracesthe 82-mile-long crosssection marked on the map at farleft.
HEAVILY CULTIVATED AREA
Rwenzori Mountains
Alpine moorl and
Montane forest Montane forest
Lake and wetland
L a k e G e o r g e
UGANDADEMOCRATICREPUBLICOFTHE CONGO
Savanna-forest mosaic
THREATS Eveninprotectedareas, forestsare clearedforfarmland and fuel; goldmining isfouling streams.
THREATS The warmingtemperaturesof climatechange could shrink thisalready restricted habitat.
THREATS Overfishing istaxing lake stocks, andwetlandsare being drainedto expand farmland.
Nyiragongo
Goma
Lake Kivu
Rising magma
Fault
Lavabeds
Lavaoozesthrough fissuresin Earthscrust.
Westernescarpment
Volcaniccones
Easternescarpment
Streamsflowfromhighlandsinto an earlyLake Kivu.
Solidified layersofvolcanicrock
Arrowsindicaterelative motion oftectonicplates.
Lake sedimentsatoplayersofvolcanicrock
Faults
ENDEMIC (FOUNDNOWHEREELSE)
NOTENDEMIC
Ruwenzorituraco
Yellow-crestedhelmet shrike
LHoestsmonkey
Ruwenzoriotter shrew
Strange-nosedchameleon
Tree hyrax
Goldenmonkey
Mountain gorilla
Goliath heron
Sitatunga
Hippopotamus
African pygmygoose
Congoclawlessotter
Blue-headedcoucal
Lion
Uganda kob
Topi
Lappvultu
Giraffe
Elephant
Total species
8,668MAMMALS 385
BIRDS 1,074
REPTILES 177
AMPHIBIANS 143
FISH 480
PLANTS 6,409
Endemic
854MAMMALS 45
BIRDS 42
REPTILES 18
AMPHIBIANS 38
FISH 370
PLANTS 341
Threatened
175MAMMALS 36
BIRDS 25
REPTILES 2
AMPHIBIANS 15
FISH 24
PLANTS 73
Carbon dioxide bubblesup anddissolvesin the lakesdepths.
Lavaflowfrom2002 eruption
Acacia tree
Cand
Papyrus
Giant lobelia
Papyrusgonolek
Giantheather
Disa stairsii
orchid
Giantgroundsel
12,500 ft
15,000 ft
10,000 ft
7,500 ft
5,000 ft
SOMALIANPLATE
SOMALIANPLATE
NUBIAN(AFRICAN)
PLATE
TANZANIACRATON
ARABIAN PLATE
Madagascar
Madagascar
TANZANIACRATON
NUBIAN(AFRICAN)
PLATE
ARABIAN PLATE
EasternRift
EthiopianRift
WesternRift
(Albertine)
INDIAN
OCEAN
GulfofA
den
RedSea
AFRICA
Realms of the AlbertineFromLake Albert through Lake Tanganyika, the 920-mile-long rift
holdsfourecosystemsvitalto itsbiodiversity.Withfertile volcanic
soiland amplerain,it alsosupportsone ofAfricasdensesthuman
populations,mainlysubsistencefarmers.Wildlifeconservationhere
also looksto healwoundsof war:Conflictsover land, resources,
and powerhave killed millionsof people in the past two decades.
AN
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Speciesnumbers,fromtheWildlifeConservationSociety,arebestestimatesasof2011andconsideredtobeminimums.
ALBERTINERIFT ECOSYSTEMS
Westernescarpment
A
B
C
D
A
B
C
D
N
Areashownin Lake Kivugeology diagrams(right top)
30 MILLIONYEARS
FROM NOW
TODAY
Three volcanoesremain active. Nyiragongoerupted in 1977 and 2002, taking lives anddisplacing hundredsof thousandsofpeople.Moltenrock beneath1,600-foot-deepLakeKivureleasescarbon dioxide, which getstrappedin the lake. Ifan earthquake or eruption freedthe gas, along with trapped methane, thedeath tollwould be catastrophic.
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POPUL TIONDENSTYPOPULATIONDENSITYPeople persq km sq mPeople persq km(sq mi)50 (130)
100 (260)
200 (520)
500 (1,300)
1,000 (2,600)
DESIGN: JUAN VELASCO TEXT:SHELLEY SPERRYART:ALDO CHIAPPE WILDLIFE,GARY HINCKS GEOLOGYRESEARCH:BARBARA L.WYCKOFF PRODUCTION: SANDI OWATVEROTNUZZO CONSULTANTS: ALEXANDRIA L. GUTH, MICHIGAN TECHNOLOGICAL UNIVERSITY;ANDREW J. PLUMPTRE, WILDLIFE CONSERVATION SOCIETY;JOHN BATES AND VELIZAR SIMEONOVSKI, FIELD MUSEUM; HENK BEENTJE,ROYAL BOTANIC GARDENS, KEW; JULIAN KERBIS, ROOSEVELT UNIVERSITY; JOS SNOEKS, ROYAL MUSEUM FOR CENTRAL AFRICAMAPS:ROSEMARY P.DALEY,DEBBIE GIBBONS,JULIE A.IBINSON,JAMES E.MCCLELLAND,JR.MAP DATA: TERRESTRIAL ECOREGIONS GISDATABASE,WORLD WILDLIFE FUND;SRTM DATA,INTERNATIONAL CENTRE FOR TROPICAL AGRICULTURE;NASAEARTH OBSERVATORY;MODIS/TERRA VEGETATION CONTINUOUS FIELDS,NASA;UMD GLOBAL LAND COVER CLASSIFICATION,UNIVERSITY OF MARYLAND;OAK
RIDGE NATIONAL LABORATORY LANDSCAN2009/UTBATTELLETECTONIC MAPS: STANISLAW MAZUR,GETECH;AFAR RIFT CONSORTIUM,UNIVERSITY OF LEEDS DATA
MORE ON NATIONAL GEOGRAPHIC MAPS AND ITS PRODUCTS AT NATGEOMAPS.COM OR CALL 18009621643
COPYRIGHT 2011 NATIONAL GEOGRAPHIC SOCIETY, WASHINGTON, D.C. PRINTED SEPTEMBER 2011
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The elevationprofile offourecosystems(rightcenter)followsthis82-mile-longcrosssection.
THREATENED ORVULNERABLE
ENDANGERED
SPECIESKEY
Magma
Bottego 15,418 ft
Musanze(Ruhengeri)
UGANDA
RWANDA
Rubavu(Gisenyi)
UGANDADEM.REP.OFTHECONGO
DEM
.
REP
.OFTH
ECONGO
RWANDA
7SEVEN BILLION S PECIAL S ERIES
0 mi 100
0 km 100
A Montaneforest
B Alpinemoorland
C Lake andwetland
D Savanna-forestmosaic