At Vivi the country is much eroded, granitic rocks, schist, mica, gneiss, and quartz are exposed. The hill-sides are rock strewn, and the country is wild and desolate, covered with weak grass and stunted gnarled trees. In the more level spots rich soil has collected, and the natives cultivate there their cassava, ground-nuts, etc. This is the nature of the country for the next fifty miles. Near the river a chaos of hills, further away rolling plateau, covered with strong grass and stunted trees. The tops of these _nzanza_, by Mr. Stanley’s careful survey, vary but fifty feet over stretches of forty miles. Above Isangila limestone crops up with slaty rocks, the main level near the river is lower, and traversed by straight ridges of hills running parallel with the coast, and from five to ten miles apart. Clear of the limestone, the country is once more a torn plateau, slate and shale abound, until at 200 miles from the coast occurs a very marked step of 700 feet. Here the country is from 2,300 to 2,500 feet above the sea, and continues so, the rock being a red or purple sandstone. Several higher ridges cross the country as you near Stanley Pool, cut abruptly by the gorge of the river, and continued on beyond. Stanley Pool is a widening out of the river in a weak point among the hills, which marks the head of the cataract region, the water level being about 1,000 feet above the sea. The plateau country continues for a further 150 miles, when hills disappear, and the main level appears to be about 1,100 feet above the sea. From Irebu, 250 miles above the Pool, to Stanley Falls, the banks are forest-clad. The country then divides itself into three regions between the coast and Stanley Falls. The lower river 100 miles, cataract region 200 miles (nearly 300 miles in winding course), the upper river 1,060 miles. Or coast level fifty miles, plateau level 400 miles, central level 900 miles, of which 800 miles are forest-clad banks. The cataract region is the obstacle that has kept so long secret this great highway; but that passed, on the upper river there are 1,100 miles of unimpeded navigation, while the affluents are estimated at 2,000 miles; beyond the Stanley Falls stretch another 2,000 miles of riverway. Two of the affluents have been explored, and on each was found a lake, while the natives at the mouths of other affluents speak of lakes. It is highly probable that further explorations will reveal other lake regions, all available to the steamers and boats on the upper river.