By G. HARVEY SHEPARD

For two hours we watched storm clouds gather as our speedboat cut through coffee-colored waves on the Içana River.  We beached at the base of a sandy cliff called Paitsidzapani in the Baniwa language, named for a kind of edible frog. Brazilian Portuguese has no word for such herpetological minutiae, so the Baniwa also call the place Serra do Desafio da Vida, or “Challenge of Life Hill.”  Baniwa Indians stop here to partake of its dual enchantments: some stay at the base to gather coal shards endowed with a miraculous capacity to promulgate the eponymous (and by all accounts delectable) frogs. The brave, however, look towards the top, fix their eyes on dry twigs lining the precipice, and climb the steep embankment.