The PASTAZA (the ancient river Sumatara) is a large
tributary to the
Amazon River. It rises on the Ecuadorian tableland, where
a branch from the valley of Riobamba unites with one from
the Latacunga basin and breaks through the inland range
of the Andes; and joined, afterwards, by several important
tributaries, finds its way south-east among the gorges;
thence it turns southward into the plains, and enters the
Amazon at a point about 60 miles west of the mouth of the
Huallaga. So far as known, it is a stream of no value
except for canoe navigation. Its rise and fall are rapid
and uncertain, and it is shallow and full of sandbanks
and snags. It is a terrible river when in flood.