Fun fact: Mount Kilimanjaro is actually three
volcanoes, two of which are extinct and one dormant. The tallest of the three – the one you see in all the pictures – is called Kibo. It’s also the youngest and the one that’s not quite dead yet. The highest point on Kibo – and therefore the bulls-eye for all summit-seekers – is a spot on the southern lip of Kibo's crater rim called Uhuru Peak. The oldest of the three volcanoes is called Shira, and it first erupted some 750,000 year ago. Pause a moment to let that sink in. Shira blasted its way out of the earth before our species existed. Waaaay before. And it continued erupting, on and off, for about 250,000 years. That’s still before early humans evolved, although by that time a few of our early hominid ancestors were indeed tottering around East Africa on two unsteady feet.
Shira finally ran out of steam, so to speak, about 500,000 years ago, just as a new volcano, Mawenzi, thrust upward from the valley floor to the east. Mawenzi erupted feverishly for about 40,000 years, give or take, before handing off its fiery baton to Kibo. Head spinning yet? Still no humans. The first of our kind wouldn’t appear for another – wait for it – 200,000 years. If any early hominids got close enough to Kibo's fireworks to scorch their protruding brows, it would have been Homo erectus or Homo hiedelbergensis, not Homo sapiens. And those guys are pretty distant relations. We don’t even invite them to the reunions anymore.
Kilimanjaro looks the way it does now because Mawnezi buried most of Shira’s cone under lava, and then Kibo did the same to Mawenzi. Kibo finally called it quits – for the most part – about 360,000 years ago, and the three sisters began to take the shape so familiar to us today. The piles of giant boulders and flows of hardened lava that belched out of the mountain in its fire-breathing days have been eroding for millennia under the slow, relentless pressure of wind, rain, and even ice. As a result, Kibo today looks like the decapitated neck of someone wearing Bette Davis shoulder pads. (You see that, too, right?)
Shira finally ran out of steam, so to speak, about 500,000 years ago, just as a new volcano, Mawenzi, thrust upward from the valley floor to the east. Mawenzi erupted feverishly for about 40,000 years, give or take, before handing off its fiery baton to Kibo. Head spinning yet? Still no humans. The first of our kind wouldn’t appear for another – wait for it – 200,000 years. If any early hominids got close enough to Kibo's fireworks to scorch their protruding brows, it would have been Homo erectus or Homo hiedelbergensis, not Homo sapiens. And those guys are pretty distant relations. We don’t even invite them to the reunions anymore.
Kilimanjaro looks the way it does now because Mawnezi buried most of Shira’s cone under lava, and then Kibo did the same to Mawenzi. Kibo finally called it quits – for the most part – about 360,000 years ago, and the three sisters began to take the shape so familiar to us today. The piles of giant boulders and flows of hardened lava that belched out of the mountain in its fire-breathing days have been eroding for millennia under the slow, relentless pressure of wind, rain, and even ice. As a result, Kibo today looks like the decapitated neck of someone wearing Bette Davis shoulder pads. (You see that, too, right?)
Although Kibo is classified as dormant, it’s not entirely quiet. There was apparently some volcanic activity up there about 200 years ago, and even today fumaroles and steam vents puff out hot, stinky sulfur gases inside the caldera. In fact, scientists now believe that there’s molten magma just 1000 feet below the summit crater. Yikes!
Thankfully, new eruptions are not considered imminent; however, a big rumble or shake could occur at any time. And anything more jiggly than a light shudder might cause a major collapse like the one that created the massive Western Breach, where rock slides are still a fairly common occurrence. A popular summit route, the Western Breach was closed temporarily after three climbers were killed there by rockfall in 2006. And when I say rockfall I mean nearly 40 tons of boulders careening down a giant chute that's funneling everything right into the faces of anyone who happens to be coming up at the time. Many park rangers think that the Breach route should still be closed.
Cold nights and bright sunny days conspire to create a daily freeze-thaw cycle that keeps Kibo’s slopes dangerously loose and unstable. During the day, meltwater finds its way into tiny fissures in the rocks where it freezes at night, expands, and forces the fissures open a bit wider. Each day, more meltwater fills slightly larger fissures until, eventually, there’s just not much holding things together up there. Then gravity takes over and pulls the whole Jenga tower down to a lower elevation. It’s all just basic physics and geology, of course – unless you happen to be under it.
The good news is that Monica and I will not be summiting via the Western Breach. We will, however, have to spend a few tense hours traversing across its base. I, for one, plan to tip-toe.
The good news is that Monica and I will not be summiting via the Western Breach. We will, however, have to spend a few tense hours traversing across its base. I, for one, plan to tip-toe.