ONE hundred and forty-four years ago, London was buzzing with excitement. Johannes Rebmann, a German explorer, had reported seeing a great mountain in East Africa, a mountain so tall that its peak was crowned with snow. Though many marveled at this sensational news, professional geographers shook their heads. Snow on the equator? Only in Rebmann’s imagination, they concluded.

But the experts were wrong in both cases. Further exploration confirmed the existence of lofty Kilimanjaro, adorned with snow the year around.

Cutting through the area from north to south is the Great Rift Valley, a 4,000-mile-long [6,400 km] cleavage in the earth’s crust. Along this valley are extinct volcanic mountains. The most famous of these is Mount Kilimanjaro. At almost 20,000 feet [6,000 m], it is Africa’s highest mountain.