ACROSS UNKNOWN SOUTH AMERICA 
The centre of the basin was of immense depth. Directly 
under the fall a spacious grotto was to be seen under a 
huge projecting rock. 
The elevation of the stream above the falls was 2,150 
feet, below the falls 2,060 feet. The temperature of the 
atmosphere was 72° Fahrenheit, and the minimum tem¬ 
perature during the night 58° Fahrenheit. 
The Roncador flowed from northeast to southwest as 
far as the foot of the great plateau we had observed during 
our march. There, on meeting the great vertical wall, its 
course was diverted in a northerly direction and then again 
to the northwest, where the stream eventually fell into the 
Cuyaba River. The Rio Jangada, on which we had 
camped the previous day, was a tributary of the Roncador, 
and so was the streamlet called Pedra Grande, which 
entered the Roncador on its right side. The Pedra 
Grande took its name from an immense monolith, worn 
quite smooth, near its bank. 
From the Roncador we continued on our northerly 
course. The western view of the “ balanced Sphinx 
boulder ” was indeed remarkable. It seemed to stand 
upon a small pivot, despite all the laws of gravitation, the 
heaviest side of the upper rock projecting far out on one 
side with nothing to balance it on the other. 
Cutting our way easily in the scrub, we rose to 2,800 
feet over a flow of red lava (it had flowed in an easterly 
direction) in several successive strata. The upper stratum 
was grooved into geometrical patterns, such as we had 
met before, wherever it showed through the thin layer of 
red, volcanic sand which covered most of it. We were 
there in a zone of immense, natural pillars of rock, some 
of such great height that they were visible miles off along 
the range, which extended from south to north, parallel, in 
fact, to the course we were following. 
Still proceeding due north, we arrived on the summit 
of a great dome, 2,500 feet, from which point we had to 
320 
