Climate and Geology

The development of high plateaux and mountains in East Africa began 30 to 40 million years ago in early Tertiary times. Profound geological activity led to rift valley formation, fissures in the earth’s crust and the formation of volcanic cones.

Kilimanjaro’s main period of development occurred during the last 3 million years. Weaknesses in the earth’s crust resulting from the Tertiary upheavals allowed outflows of lava that created the three domes of Shira, Mawenzi and Kibo. It is likely that Shira and Mawenzi preceded Kibo, the highest of Kilimanjaro’s three cones.

Shira sank to become a caldera as Kibo’s outflows released pressure below the collapsing volcano. Erosion and filling with lava flow from Kibo have left the wonderful Shira Plateau still rimmed with remnants of the once magnificent cone.

Mawenzi is the most spectacular of the three volcanic centres with its sharp pinnacles and ridges and dramatic sheer eastern face. Mawenzi did not sink to become a caldera like Shira, rather it has been eroded by the elements with the harder volcanic rocks remaining as the dramatic, fairy tale pinnacles that we see today.

Kibo, the object of most climbers’ attentions, is the youngest and now the highest of Kilimanjaro’s cones and we can assume that much of the activity that created Kibo occurred in the last 500,000 years. The main crater floor has partially collapsed, leaving inner walls on the south side as high as 180 metres. Within this caldera has developed an Inner Cone, whose centre is the Reusch Crater. Fumaroles testify to the dormant status of Kilimanjaro.

Throughout the Kilimanjaro massif are found parasite craters – initially formed by lava flowing from small breaches or fissures in the sides of the old volcanic cones. On the popular route Maundi Crater near Mandara Hut is a perfect example of the parasite cone. To the north west the wonderful Lent Group offer a more dramatic and remote example of parasite activity.

High altitude and periods of intense cold led to the formation of glaciers on the higher points of Kilimanjaro. Still spectacularly evident today in the form of icefields, rim glaciers, and the incredible ice cliffs found actually within the crater, these ice formations are, nevertheless, receding as the globe warms up.

The setting for these ice sculptures is a high altitude desert of rock slab, scree, and rugged formations. Being above the normal cloud height, precipitation is so limited on these higher slopes of Kilimanjaro that here is truly found a high altitude desert.