A Samburu warrior looks out over a vast expanse of inhospitable country from the eastern scarp of Africa's Great Rift Valley at Losiolo, north of Maralal. From 8,000 feet the land tumbles away 3,000 feet into rugged valleys and a broad plain, the domain of nomadic pastoralists, before rising again 75 miles away. The views at Losiolo are the most spectacular in Kenya of the largest, longest and most conspicuous physical feature of its kind on earth.