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Mount Kilimanjaro , with its three volcanic cones, "Kibo", "Mawenzi", and "Shira", is a dormant volcanic mountain in Tanzania. It is the highest mountain in Africa, and rises approximately from its base to above sea level. The first recorded ascent to the summit of the mountain was by Hans Meyer and Ludwig Purtscheller in 1889. The mountain is part of the Kilimanjaro National Park and is a major climbing destination. The mountain has been the subject of many scientific studies because of its shrinking glaciers. ==Geology and physical features== Kilimanjaro rises approximately from its southern base in the plains near the municipality of Moshi to its summit height of . Kilimanjaro is the highest volcano outside South America.〔(【引用サイトリンク】 title=Mt Kilimanjaro Volcano )〕 Kilimanjaro is a large stratovolcano and is composed of three distinct volcanic cones: Kibo, the highest; Mawenzi at ; and Shira, the shortest at . Mawenzi and Shira are extinct, while Kibo is dormant and could erupt again. Uhuru Peak is the highest summit on Kibo's crater rim. The Tanzania National Parks Authority, a governmental agency, and the United Nations Educational, Scientific and Cultural Organization〔 list the height of Uhuru Peak as . That height is based on a British Ordnance Survey in 1952. Since then, the height has been measured as in 1999, in 2008, and in 2014.〔 The interior of the volcanic edifice is poorly known, given the lack of large scale erosion that could have exposed the interiors of the volcano. Eruptive activity at the Shira centre commenced about 2.5 million years ago, with the last important phase occurring about 1.9 million years ago, just before the northern part of the edifice collapsed.〔 Shira is topped by a broad plateau at , which may be a filled caldera. The remnant caldera rim has been degraded deeply by erosion. Before the caldera formed and erosion began, Shira might have been between and high. It is mostly composed of basic lavas with some pyroclastics. The formation of the caldera was accompanied by lava emanating from ring fractures, but there was no large scale explosive activity. Two cones formed subsequently, the phonolitic one at the northwest end of the ridge and the doleritic "Platzkegel" in the caldera centre.〔〔 Both Mawenzi and Kibo began erupting about 1 million years ago.〔 They are separared by the "Saddle Plateau" at elevation. The youngest dated rocks at Mawenzi are about 448,000 years old.〔 Mawenzi forms a horseshoe shaped ridge with pinnacles and ridges opening to the northeast which has a tower like shape resulting from deep erosion and a mafic dyke swarm. Several large cirques cut into the ring, the largest of these sits on top of the Great Barranco gorge. Also notable are the Ost and West Barrancos on the northeastern side of the mountain. Most of the eastern side of the mountain has been removed by erosion. Mawenzi has a subsidiary peak named Neumann Tower ().〔〔〔 Kibo is the largest cone and is more than wide at the "Saddle Plateau" altitude. The last activity here has been dated to between 150,000 and 200,000 years ago and created the current Kibo summit crater. Kibo still has gas-emitting fumaroles in the crater.〔〔〔 Kibo is capped by an almost symmetrical cone with escarpments rising to on the south side. These escarpments define a caldera〔 caused by the collapse of the summit. Within this caldera is the Inner Cone and within the crater of the Inner Cone is the Reusch Crater, which the Tanganyika government in 1954 named after Gustav Otto Richard Reusch upon his climbing the mountain for the 25th time (out of 65 attempts during his lifetime). The Ash Pit, deep, lies within the Reusch Crater. About 100,000 years ago, part of Kibo's crater rim collapsed, creating the area known as the Western Breach and the Great Barranco. An almost continuous layer of lavas buries most older geological features, with the exception of exposed strata within the Great West Notch and the Kibo Barranco. The former exposes intrusions of syenite.〔 Kibo has five main lava formations:〔 # phono-tephrites and tephri-phonolites of the "Lava Tower group", on a dyke cropping out at , 482,000 years ago # Tephri-phonolite to phonolite lavas "characterized by rhomb mega-phenocrysts of sodic feldspars" of the "Rhomb Porphyry group", 460,000–360,000 years ago # aphyric phonolite lavas, "commonly underlain by basal obsidian horizons", of the "Lent group", 359,000–337,000 years ago # porphyritic tephri-phonolite to phonolite lavas of the "Caldera rim group", 274,000–170,000 years ago # phonolite lava flows with aegirine phenocrysts, of the "Inner Crater group", which represents the last volcanic activity on Kibo Kibo has more than 250 parasitic cones on its northwest and southeast flanks that were formed between 150,000 and 200,000 years ago〔 and erupted picrobasalts, trachybasalts, ankaramites, and basanites.〔〔〔 They reach as far as Lake Chala and Taveta in the southeast and the Lengurumani Plain in the northwest. Most of these cones are well preserved, with the exception of the Saddle Plateau cones that were heavily affected by glacial action. Despite their mostly small size, lava from the cones has obscured large portions of the mountain. The Saddle Plateau cones are mostly cinder cones with terminal effusion of lava, while the Upper Rombo Zone cones mostly generated lava flows. All Saddle Plateau cones predate the last glaciation.〔 According to reports from the Maasai, Lake Chala on Kibo's eastern flank was the site of a village that was destroyed by an eruption. The mountain is drained by a network of rivers and streams, especially on the wetter and more heavily eroded southern side and especially above . Below that altitude, increased evaporation and human water usage reduces the waterflows. The Lumi and Pangani rivers drain Kilimanjaro on the eastern and southern sides, respectively. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Mount Kilimanjaro」の詳細全文を読む スポンサード リンク
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