AFRICA’S TWO GREATEST RIVERS originate in Africa’s two greatest lakes. Lake Victoria gives rise to the Nile, while Lake Tanganyika drains into the Congo. This geographical conceit, however, ignores the fact that both great lakes are nourished by thousands of smaller waterways that flow down from the surrounding mountains and highlands. Many of these have their source in Rwanda.

An extensive marsh occupies the saddle area between Mts. Karisimbi, Mikeno, and Visoke. About twenty minutes west of the Karisoke field station this watlands-meadow complex comes to a gentle rise, which separates the summing hummock, an eighteen inch-wide grassy channel collects the clear Virunga waters and sends them on their way towards lakes Kivu and Tanganyika, out through the Lualaba River, and on to the mighty Congo. Twenty feet away, a similar conduit forms a stream that gains in size and power as it flows in an easterly direction through camp. Joining forces with the Susa, Mukungwe, Nyabarongo, and Akagera Rivers along the way, these waters enter Lake Victoria before the final four thousand-miles push down the Nile and into the Mediterranean Sea

Besides being a geographical curiosity, camp stream was the lifeline of our existence. Fed by waters from both karisimbi and Visoke, it provided a steady source of water that was rear in the Virungas. Even constant rainfall didn’t guarantee any surface water over large areas of the park, where porous rocks and lava rocks formations quickly drained the water underground. Standing water without a flow was suspect for health reasons in any part of the park. But this was rarely a problem with camp stream, whose clear waters we drank untreated in all but the peak of dry season as it flowed thirty feet from our cabin.

In the rainy season, camp stream’s character could change in less than an hour , as runoff from the latest downpour turned it into a torrent of crashing, swirling white water. The thought of riding a tube at high water down its rollicking cascades, constrained within a rocky channel no more than ten feet wide, was a recurrent fantasy. But we didn’t have a tube-and the water temperature was barely above freezing

At one level, temperature and rainfall information were irrelevant in the Virungas. It was always cold and wet. yet a great deal of variability hid in those two adjectives. A 5-degree-Fahrenheit drop on a cloudless evening at ten thousand feet sent the temperature below freezing, while a 10-degree rise on a rare sunny day brought on a quick striptease of outer clothing layers as the thermometer approached a balmy 70 degrees. On our arrival, we were surprised to learn that karaoke had no reliable means to keep climatologically data other than a tiny plastic rain gauge under some trees and a department store thermometer attached to a window on Dian’s cabin. When Bill requested better equipment from Rwanda’s bureau meteorologique, we received a professional high-volume rain gauge and min-max thermometer that recorded daily high and lows. With their installations in appropriate sites, Rwanda gained its only high elevation rain forest monitoring station, karisoke entered the realm of modern meteorology, and were made precisely aware each day of just how cold and wet it really was

DESPITE ITS DRAMATIC RISE, Camp stream never overflowed its steep banks to flood the main residential area while we were at karisoke. It didn’t have to; we lived in a perpetual swamp. From the spot where the Congo and Nile waters parted ways less than a mile west of camp, the entire saddle area was a broad, sloping wetland. Some of its waters took fast track via camp stream, but most move more slowly as a sheet of steadily flowing, nearly freezing water. Situated on the eastern edge of the saddle, from the upper marsh. But this location only placed us closer to the slopes of Visoke, from which a tributary sheet of unchanneled water seeped almost constantly across the station as it sought to join camp stream

One of the great attractions of karisoke was the fact that so much of it was left in a natural state. No effort had been made to drain or channel large areas of mash, which retained their cover of grasses, sedges, and the 0ccupational alpine lobelia, which washed down as seeds or seedlings from the surrounding slopes. On higher ground, senecio shrubs mixed with purple-crowned thistle and thousands of yellow-flowered hypericum saplings-a relative of st. John’s-wort that grows to tree size in the virungas-to form dense thickets. These were separated by a network of grassy clearings and natural seeps. Towering over everything were the giant forms of hagenia abyssinica. Almost one hundred feet tall and six feet in diameter at the base, these trees reach their greatest size in the area immediately around karisoke. They are improbable life forms, seemingly designed by Dr. Seuss.