UCAYALE or UCAYALI, A large river of Peru (Slap: Peru, C 5). It is one of the main headstreams of the Amazon, and, judged by length and volume, it should be con sidered as the true upper course of that river. It is formed by the junction of the Apurimac (q.v.), or Tambo, and the Quillabamba at the eastern base of the Andes on the boundary be tween the departments of Junin and Cuzco, and flows northward in a much winding course till it joins the Nitration in the northeastern corner of Peru to form the Amazon. The length of the Ucayale proper is about 1000 miles, and with the Apurimac the total length is nearly 1500 miles. Some of their sources are near Lake Titi caca, while that of the 1\lantaro. a tributary of the Apurimac, is in Lake Chinchayeocha or Ju nin (q.v.) within 100 miles of Lima, on the Pa cific coast, and over 13,000 feet above the sea.
So rapid is their flow, however, that at their con fluence the I,Teayale proper is less than 1000 feet above sea level. From this point its course through the densely forested and sparsely popu lated montafio is very sluggish, falling only 500 feet in nearly 1000 miles. Its banks are here very low, and it divides repeatedly into side chan nels, while large adjacent areas are periodically submerged. The Ilcayale is navigable for the largest vessels, maintaining a depth of 40 to 70 feet for over 600 miles. Steamers can also ascend the Paehitea, the principal tributary below the confluence of the headstreams, over 200 miles to a point about 300 miles from Lima and 3600 miles from the mouth of the Amazon. The Ucavale thus affords an easy means of communi cation between the Atlantic Ocean and the heart of Peru.