It is implied in the passage that ....... .

The geological formation of the Victoria Falls of the Zambezi River makes it one of the world's
most unusual cataracts, the term for a giant waterfall. Situated between Zambia and Zimbabwe, it
spreads over a mile in width. Unlike most rivers approaching a cataract, the Zambezi has no
rapids to warn the river traveller of the approaching precipice. A shallow, broad river the
Zambezi continues to move slowly up to the brink of the falls. Then it spills abruptly over the
355-foot precipice with a thunderous roar.