Mount Kilimanjaro is a snow-capped peak rising above the savanna of eastern Africa, just 200 miles south of the equator. With a summit of 19,341 feet, this is Africa's tallest mountain. It is also the world's largest free-standing mountain
Formation
Mount Kilimanjaro was formed about three million years ago during the formation if the Great Rift Valley. Then about one million years ago volcanic activities centered on a few specific points. Kilimanjaro is made of three volcanoes lying practically on top of one another. The lowest summit, Shira, at 12,995 feet last erupted half a million years ago and is now considered extinct. The other two peaks are dormant and have not erupted for centuries. Mawenzi, at 16,896 feet is linked to the highest summit, Kibo, by a broad ridge which gives the summit of Kilimanjaro a “saddle” shape.
Shira Caldera
A caldera is a feature formed by the collapse of land following a volcanic eruption. They are sometimes confused with volcanic craters. The word comes from the Spanish meaning "bowl".
A collapse is triggered by the emptying of the magma chamber beneath the volcano, usually as the result of a large volcanic eruption. If enough magma is erupted, the emptied chamber will not be able to support the weight of the volcanic edifice above it.
Weaknesses in the earth's crust resulting from the upheavals allowed flows 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 then 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.
The Shira Caldera and Shira Camp
Assignment
1. Study a sample of the rocks in the caldera. What types of rocks are they? How do you suppose they were formed? Are they hard or soft?
2. Based on your observations at the site, can you see the walls of the caldera? Estimate how high they are
3. Send me an e-mail with the answers to 1 and 2
4. (Optional) Upload a photo of you on the Shira Plateau facing the peak of Kilimanjaro