wide, and is a frightful series of torrents and whirlpools interspersed with rocks.
The junction of the great river Beni with the Madeira is at the Madeira Fall, a vast and grand display of reefs, whirlpools and boiling torrents.
Just below this the mountains close in on either side of the Maranon, forming narrows or pongos for a length of 35 m., where, besides numerous whirlpools, there are no less than thirty-five formidable rapids, the series concluding with three cataracts just before reaching the river Imasa or Chunchunga, near the mouth of which La Condamine embarked in the t8th century to descend the Amazon.
The tidal currents, or races, or roost (as some of them are called locally, from the Icelandic) off many of the isles run with enormous velocity, and whirlpools are of frequent occurrence, and strong enough at times to prove a source of danger to small craft.
Sometimes enormous rocks have fallen from the mountains and spread over the river-bed causing huge whirlpools.