The Rwenzori Mountains lie 48km (30mi) north of the equator in East Africa. They are hidden behind dense clouds or mist for an average of 300 days each year.
The mountain range is 120km (75mi) long and 48km (30mi) broad. Margherita Peak on Mount Stanley, at 5,109m (16,763ft), is the highest point of the range.
They were formed around two million years ago when movements of the Earth's crust caused a major subsidence in the ancient Great Rift Valley, forcing the ancient granite rocks of the mountains to be thrust upward.
The Rwenzori are the only high mountains of East Africa that were not created by volcanic activity.
The name Rwenzori is a word in a local dialect that means "the rainmaker", and the mountains affect the weather throughout the savannas of central east Africa.
Westerly air currents moving across the steamy rain forests of the Congo basin pick up huge amounts of water vapor. When these moisture-laden winds strike the Rwenzori, they are rapidly forced upward.
At these higher altitudes, their water vapor condenses to form water droplets and then ice crystals. This creates almost permanent cloud cover and local precipitation - around 2m (6.6ft) a year - of rain, snow, sleet and hail.
When strong, steady winds sweep up the mountainsides, the clouds spill over the Rwenzori and ride above the broad savanna regions to the east where they cause the storms and torrential downpours of the rainy season.
Together with melted water from the glaciers, the abundant rainfall also adds water to tributaries of the Congo River and, via the waterways of eastern Uganda, to the flow of the Nile, the world's longest river.
The Rwenzori Mountains are sometimes associated with the "Mountains of the Moon" that were described by Ptolemy, the ancient Greek geographer and mathematician, who believed they were the source of the Nile.
Life on the Rwenzori
Wide swamps and marshes based on sediments and debris washed down by frequent rains occupy the valleys and cover the foothills of the Rwenzori.
Here, thick stands of reeds and grasses, including papyrus grow more than 2m (6.6ft) tall. Elephants push through this vegetation with ease, eating the grasses and startling both natives and travelers with their presence.
A variety of animals, including the three-toed chameleon, live further up the mountain slopes, in a lush evergreen zone of wild bananas and tree ferns. Sunbirds, Africa's equivalent of the New World's hummingbirds, drink nectar from lobelias and other flowers, while earthworms as long as 1m (33ft) and as thick as a man's thumb weave their way through the moist soil.
At about 2,133m (7,000ft), thick stands of bamboo provide cover for leopards, which often follow humans in search of edible refuse. The Rwenzori's most unusual creature is the rock hyrax, which resembles a rabbit in appearance and shrieks like a guinea pig. However, instead of claws it has the hoofs of an ungulate. Its nearest relative is the elephant.
Giant Plants
At altitudes of around 3,353m (11,000ft), animal life becomes scarce. However, some plants that are commonly found in temperate climates grow to enormous sizes.
Lobelias and groundsels grow up to 6 meters tall. Heathers grow up to 12 meters.
The plants are able to grow to these heights on the uppers slopes of the mountains because there is no competition from trees. Lack of competition combined with abundant, year-round moisture, mineral-rich, acidic soil and high levels of ultraviolet radiation provide the conditions for this enormous level of growth.