Leaving modern Vilcabamba, we crossed the flat, marshy bottom of an old glaciated valley, in which one of our mules got thoroughly mired while searching for the succulent grasses which cover the treacherous bog. Fording the Vilcabamba River, which here is only a tiny brook, we climbed out of the valley and turned westward. On the mountains above us were vestiges of several abandoned mines. It was their discovery in 1572 or thereabouts which brought Ocampo and the first Spanish settlers to this valley. Raimondi says that he found here cobalt, nickel, silver-bearing copper ore, and lead sulphide. He does not mention any gold-bearing quartz. It may have been exhausted long before his day. As to the other minerals, the difficulties of transportation are so great that it is not likely that mining will be renewed here for many years to come. At the top of the pass we turned to look back and saw a long chain of snow-capped mountains towering above and behind the town of Vilcabamba. We searched in vain for them on our maps. Raimondi, followed by the Royal Geographical Society, did not leave room enough for such a range to exist between the rivers Apurimac and Urubamba. Mr. Hendriksen determined our longitude to be 73° west, and our latitude to be 13° 8' south. Yet according to the latest map of this region, published in the preceding year, this was the very position of the river Apurimac itself, near its junction with the river Pampas. We ought to have been swimming "the Great Speaker." Actually we were on top of a lofty mountain pass surrounded by high peaks and glaciers. The mystery was finally solved by Mr. Bumstead in 1912, when he determined the Apurimac and the Urubamba to be thirty miles farther apart than any one had supposed. His surveys opened an unexplored region, 1500 square miles in extent, whose very existence had not been guessed before 1911. It proved to be one of the largest undescribed glaciated areas in South America. Yet it is less than a hundred miles from Cuzco, the chief city in the Peruvian Andes, and the site of a university for more than three centuries. That Uilcapampa could so long defy investigation and exploration shows better than anything else how wisely Manco had selected his refuge. It is indeed a veritable labyrinth of snow-clad peaks, unknown glaciers, and trackless canyons. Looking west, we saw in front of us a great wilderness of deep green valleys and forest-clad slopes. We supposed from our maps that we were now looking down into the basin of the Apurimac. As a matter of fact, we were on the rim of the valley of the hitherto uncharted Pampaconas, a branch of the Cosireni, one of the affluents of the Urubamba. Instead of being the Apurimac Basin, what we saw was another unexplored region which drained into the Urubamba!