Kilimanjaro National Park

The Great Rift Valley was long in developing, only reaching its present form between one and two million years ago. Where Kilimanjaro was to stand there was a gently undulating plain, with a few old eroded mountains. A million years ago the plain buckled and slumped. Fractures and faults allowed molten rock from below the earth's crust to find routes to the surface; volcanoes emerged and the plain became dotted with cones and craters. The splitting and sinking of the land created a huge basin, the Kilimanjaro Depression. At least three volcanoes vented forth, Ol Molog, Kibongoto and Kilema, which built up an enormous "ridge," 100 km long, 65 kms wide and 3,000 meters high. These heralds of the coming Kilimanjaro can still be found about 30 kms away.

Kilimanjaro began to grow out of and over the fractures 750,000 years ago, with lava coming from three main centers: Shira, Kibo and Mawenzi. Their cones grew over thousands of years, reaching about 5,000 meters in height. Shira collapsed into a caldera and became inactive 500,000 years ago. Kibo and Mawenzi continued to grow, their lavas intermingling, reaching 5,500 meters. Then Mawenzi died and rapidly eroded. Kibo continued to grow, producing several more lava flows. The most extensive eruptions, 360,000 years ago, produced a black lava that filled the old eroded Shira caldera, fanned out over the Saddle and the base of Mawenzi and flowed far to the north and south. This lava, known as rhomb porphyry lava, is distinctive because of its dark color and embedded rhombic or diamond-shaped crystals.

Kilimanjaro ceased growing 450,000 years ago. Kibo peak was then about 5,900 meters tall and from this time the whole mountain began to shrink. Eruptions continued intermittently and during the periods of dormancy erosion sculpted the form of the mountain, leaving the peaks and spires of the hard core of Mawenzi, and the gentle plateau of Shira. Kibo flattened and subsided into concentric terraces and cones while being repeatedly covered and uncovered by glaciers. Some 100,000 years ago a huge landslide carried away some of the summit and created the huge Kibo Barranco. Volcanic activity became sporadic. Many parasitic vents erupted, leaving a band of distinctive cones and craters running across Kilimanjaro in a south-east to north-west direction. Finally, Kibo had a last gush of activity, which formed the present caldera, the flows of the Inner Crater and the Ash Pit.

Glaciers returned and the mountain eroded into its present shape. Forests grew on the well-watered lower slopes, and vegetation gradually claimed what it could of the rest of the mountain as streams steadily wore creases in the aging massif. Weathering continues to shape the mountain and Kibo appears to be losing its glacial ice cap.

Planet Zones
Mt. Kilimanjaro has five major plants zones:

• Lower slopes
• Forest
• Heath and moorland
• Highland desert
• Summit

Within each zone there is an association between altitude, rainfall, temperature, plants and animals. The zones occupy belts of approximately 1,000 meters of altitude each. In general, the temperature falls between one degree centigrade for every 200 meters' increase in altitude and rainfall also decreases steadily with altitude from the forest upward. Plant life, in turn, is abundant in areas of high temperature and high rainfall. As you climb you will see that plant life decreases, not because of the height, but because conditions are colder and drier. Since animal life is dependent on plants, fewer animals live at higher altitudes.