Mount Kilimanjaro wasn’t always a tourist attraction and at one point didn’t even exist. The Great Rift Valley took a long time to form and around 1 million years ago, huge pressure forced molten rock from the earth’s crust through a large fault line that runs through East Africa to reach the earth’s surface.

Two things happened, land fractured, split and sank to form a huge basin and the thrust of this core pressure also caused volcanoes to emerge; Shira, Mawenzi and Kibo being the three most prominent. Continued activity allowed the volcanoes to grow over thousands of years to around 5000m, until around 500,000 years ago, Shira collapsed into a caldera, and became inactive. (A caldera is a large volcanic crater, which is formed when the mouth of the volcano collapses).

Kibo and Mawenzi continued growing to over 5500m, but eventually Mawenzi also became extinct, retaining its shape, but eroding to what we know as Mawenzi Peak today. Kibo remained active, with multiple eruptions, the most significant being around 360,000 years ago where rivers of black lava flowed down its slopes to fill Shira’s caldera and in and around the base of Mawenzi to form what is known today as ‘The Saddle’. Kibo has subsided over time and around 100,000 years ago there was a massive landslide, which cut through the side of the mountain to form a huge gorge (or barranco) 300m deep, which is now known as Barranco Valley.

Its last eruption was around 200 years ago and today Kibo lies dormant. Although activity is unlikely, you may be able to smell sulphur on Kilimanjaro if trekking around the Reusch Crater.