THE GREAT RIFT VALLEY

THE GREAT RIFT VALLEY

The world has many great mountains, lakes, deserts and oceans. But of its valleys and gorges one alone dwarfs them all in size and dimension. Indeed, after the oceans, the Great Rift Valley is perhaps the single most dramatic feature on earth. In Kenya much of the Rift remains an expanse of raw Africa that dazzles the eye with its haunting grandeur. Nowhere is it more apparent, more dramatic, or more picturesque. Entering the country in the north from Ethiopia through the jade waters of Lake Turkana, it slices right through the middle of Kenya like a broad knife-cut to enter Tanzania in the south at Lake Natron incorporating cliffs, escarpments, sand rivers, and arid plains flowing like molten lava from the north down to the low-lying, heat ridden, soda lakes in the south, in some places this natural divide is up to 100 kilometres wide.

The valley floor rises from little more than 200 metres above sea leval at Lake Turkana to reach its highest point around Lake Naivasha at 190 metres, before descending abruptly to enter Tanzania just 580 metres above sea level. Where the valley floor is at its highest so, too, are the valley's precipitous walls, reaching 3964 metres in the Aberdares above Naivasha. Where the floor is at its lowest, as at Turkana, there is virtually no distinction between the Great Rift and the stark, arid wilderness that adjoin it.

To the east, the featureless semi-desert scrub stretches across hundreds of kilometres to Solamia's Indian Ocean coastline. Yet in other places, where the floor is not much more than 610 metres above sea level, its great cliffs rise sheer above it for more than 1520 metres. The power that transformed the face of the world is evident in the Rift's thirty active and semi-active volcanoes and countless boiling springs. They bring sodium carbonate bubbling up from deep beneath the earth, turning many Rift lakes into bitter pans of water or blistering soda flats. This string of alkaline lakes and boiling springs northwest of Nairobi includes Lake Baringo, Lake Bogoria, Lake Nakuru, Lake Elementaita, Lake Naivasha and Lake Magadi in the south. These lakes are unique because their water is highly concentrated sodium carbonate. This situation is caused by the high alkalinity from the surrounding volcanic rocks coupled with poor drainage outlets due to the steep sides of the valley. The high evaporation of the surface lake water results in sodium carbonate which, in turn, creates an ideal breeding ground for algae. Several species of fish, tilapia in particular, thrive in this environment. As a result, millions of birds flock to these soda lakes to feast on the abundant food supply of algae and fish. Each of the lakes in the Rift Valley string have a slightly different water composition ranging from freshwater to extremely alkaline, highly saline to brackish.

Today the Kenya and Tanzania sections of the Rift are the world's last treasury of cultures, flora, and fauna, both terrestrial and avian, that have continued unchanged for centuries. The valley plains contain the last great assembly of African wildlife and from one end to the other, Kenya's human cultures form a cross-section of the entire African continent's cultural wealth. Little wonder, perhaps, that many then think of this as Eden.