Sometimes there comes along a mountain that is so unique, photogenic or iconic that its status as a volcano could almost go ummentioned. This week’s hideaway has been seen in many photos and postcards and mentioned in songs, stories and legends, but I wanted to learn about its volcanic side, so I flew off to Africa to the north of Tanaznia to get to know Kilimanjaro a little better.
Kilimanjaro is actually a complex of three stratovolcanoes trending northwest-to-southeast. The oldest stratovolcano on the northwest is called Shira, and began erupting about 2.5 million years ago. It now appears as a 3,800 m high plateau thought to be the eroded remnants of a filled caldera. Before caldera formation, Shira may have been as tall as 5,200 m. Shira ceased activity around 1.9 million years ago.
On the opposite end of the complex there is the severly eroded Mawenzi crater, which was active from around 1 million to 448,000 years ago. The prominent collection of pinnacles are actually just the least eroded part of the ancient volcano which is only evident now as a horseshoe shaped ridge. Heavy erosion of the rocks surrounding a mafic dike swarm produced the pennacles, making Mawenzi today a real test of skill for only the boldest climbers.
In the middle there is Kibo, the tallest and most recently active of the three. Kibo was constructed at about the same time as Mawenzi, but has had far more recent activity than its southeastern sibling. The highest peak, called Uhuru Peak, reaches 5,895 m skyward, making it the highest mountain in Africa. (Mawenzi, by the way, is the third highest mountain in Africa.) The most recent major eruption of Kibo took place between 150,000-200,000 years ago and created the 2.5 km wide summit caldera with high escarpments along the southern rim. Within the caldera is an inner cone which contains Reusch Crater. In the centre of Reaush Crater lies the 350 m deep ash pit, aptly named The Ash Pit. Around 100,000 years ago, a collapse of the western caldera rim created the scar known as the Western Breach on Kibo’s summit. These days, the caldera still contains active fumaroles, thus earning the sleepy Kilimanjaro volcano the status of “dormant” rather than “extinct”.Kibo’s summit plateau hosts an ice cap that covers all but the inner crater and is divergent at the plateau’s edge, forming individual glaciers. The glaciers are relatively thin and thus do not “flow” like most glaciers, but they do advance and retreat due to cimate changes, which have occured many times during Kilimanjaro’s existence. In fact, some ice core samples indicate that the ice cap may have vanished completely during a prolonged and particularly arid period 11,500 years ago, a time of drastic and sudden climate change called the Younger Dryas stadial. Over the last century, the ice has been vanishing quickly, In the last 100 years, the ice cap has lost over 80% of its mass and some estimate it may be completely gone within the next 20 years.
For you rockheads out there, the main rock types found at Kilimanjaro are phonolite, phonotephrite, and tephriphonolite. And if you, like me, are wondering what the difference is between the last two, they are both intermediate compositions between phonolite and tephrite, but tephriphonolite is closer to phonolite than phonotephrite. Phonotephrite is less alkali content (7-12%) and less silica (45-53%) than tephriphonolite (9-14% alkali and 48-57%).
I have a newfound respect for the nitpicking thoroughness of mineralogists.
Now…on to the fun stuff..Kilimanjaro trivia!
In addition to having the highest peak in Africa, Kilimanjaro is also the highest active or dormant volcano in the world outside of South America. Of the world’s free-standing mountains (not belonging to a range), it is the tallest.
There are six different ecological systems on the mountain.
1) cultivated land
5) alpine desert
6) arctic summit
Coffee is a significant export produce grown on the lower slopes of Kilimanjaro. (Volcanoes make the best beans it seems.)
At Uhura Peak, there is a wooden box containing a book in which just about everybody who has summited Kilimanjaro has added some notes about their thoughts and feelings upon their achievement.
An international tree-planting effort is taking place to help reverse the climate-drying affect of deforestation in the area and hopefully preserve the ice caps on Kilimanjaro
South African Bernard Goosen scaled Kilimanjaro twice…in a wheelchair! Goosen, who has cerebral palsy, used a modified chair and did the ascent mostly with no assistance.
Douglas Adams, author of Hitchikers Guide To The Galaxy, once ran up the volcano dressed in a rhinoceros costume. (This sounds too silly to even be true, but where English humour authors are concerned, NOTHING can ever really be too silly.)
Kilimanjaro’s name’s meaning is a much-disputed topic, but the most popular theory is that it is a Swahili name that means “shining mountain”.
A legend told by the Chagga people who live around the volcano says that Kibo and Mawenzi were once good friends, but Mawenzi threw away the embers that Kibo had given to him and then lied to Kibo, saying that they had burned out. Angry Kibo dealt Mawenzi a savage beating, which explains Mawenzi’s eroded appearance as well as his name, which is a Chagga name meaning “battered”. And as such legends go, might be how the Chagga people explain why only one of the two volcanoes displays signs of activity.
Well I’ll be darned..it IS true..and for a good cause!
Congratulations, Aficientífico, for being the first to find me, followed by Jesper, and lastly by Glenn. Thank you as always to those who hunted as well as those who just read along. For those just finding this blog, feel free to jump right in and play along. This coming Monday at/around 23:00 NYC-time (03:00 UTC) for a new adventure at a new volcano.