We travelled again that same day on the northern edge of the great depression, and met three more cuvettes of grey ashes with an abundant central growth of buritys. These were at a general elevation of 2,300 ft., the bottom of the depression being 50 ft. lower. On descending from the table-land, through a gap we discerned far away to the south a long flat-topped plateau extending from south-west to north-east and having a precipitous wall-face.
We got down to the Caxoeirinha stream, where we found an abandoned hut in the eroded hollow of the stream. The water flowed there over a bed of red lava and extremely hard conglomerate rock made up of lava pebbles and solidified ashes. Above this at the sides of the stream was a stratum some 10 ft. thick of grey ashes, and above it a stratum 2 ft. thick of red volcanic dust and sand.
As we got higher again and I stood on a projecting promontory, another wonderful view spread itself before me. The sun, nearly setting, in glorious white radiations, cast deep blue and violet-coloured shadows upon the great abyss to my right (N.W.) which was a kilometre or more in diameter and more than 300 ft. deep—surely another great crater. It seemed as if a natural wall of rock must have once existed, joining the promontory on which I stood to the great mass of prismatic red volcanic rock to the west of us, and ending in a flat triangle with a wide base. The surface soil on the height of the peninsula was of spattered lava and black broiled rock and pellets.
The bottom of the abyss formed two sweeping undulations—the second from the centre much higher than the first—seemingly a great wave of lava vomited by the crater, by which probably the destruction of the wall joining the peninsula had been caused.
To the S.S.E. in the distance stood a high mountain range—or rather a great flat-topped plateau of delicious cobalt blue shades, almost losing itself in the sky. To the east, completing the circle, were two other great spurs of red-baked rock, with precipitous, almost vertical, sides and with much-striated buttresses that ended in conical mounds—eroded into that shape by the action of water and wind.
To the south, beyond, a sloping table-land with a pronounced dip eastward extended from east to west. It towered over everything, and was shaped like a trapezium. In front of this sloping table-land was another long flat-topped range, stretching from E.S.E. to W.N.W. Again in front of this, could be seen an interesting series of prismatic mounds—like parallel barriers. To the S.S.W. rose a large mountainous mass—another plateau. Then came a second range, cut into clear pyramids with rectangular bases, and, beyond, a great expanse of lovely green with some large mounds of a similar shape to those already described. Two more pyramids were also to be observed far, far in the distance, while others of a slightly less angular shape were noticeable upon the great flat stretch due west.
Right under us, at the bottom of the precipice, was thick forest covering, zigzag fashion, the two depressions, roughly in a general direction of south-east to north-west. Those two depressions drained that immense basin. It was there that the streamlet Caxoeirinha had its birth. The Caxoeirinha flowed north-west and fell into the Ponte de Pedra River, which flowed south. Those two streams, with a number of others, formed the head-waters of the great S. Lourenço River, a formidable tributary of the Rio Paraguay or Paraná.
An extraordinary effect of clouds could be seen that day, and a similar occurrence I saw on many other occasions upon the table-lands of Matto Grosso. The clouds reproduced—upside-down—the configuration of the country directly underneath them. That was due, no doubt, to the air currents diverted by the obstacles on the earth's surface, which caused the masses of mist above to assume similar forms—but of course, as I have said, upside-down.
We were still at an elevation of 2,150 ft. The temperature during the night went down to 52° Fahr. My men, as usual, suffered intensely from the cold—at least, judging by the noise they made, the moans and groans and chattering of teeth. They nearly all had violent toothache. Alcides, too, apparently went through agony, but he showed a little more manliness than the rest and did not make quite such a pitiful exhibition of himself.
It was curious how certain racial characteristics were difficult to suppress in individuals. Alcides had some German blood in him—rather far removed. He could not speak German, nor did he know anything about Germany. Yet German characteristics came out in him constantly. For instance, the uncontrollable desire to write his own name and that of his lady-love on trees and rocks all along our passage. Alcides was really very good at calligraphy, and some of his inscriptions and ornamentations were real works of art. Many half-hours did we have to waste at the different camps, waiting for Alcides to finish up the record of his passage in that country, and many blades of penknives—I had a good supply of them to give as presents to natives—did he render useless in incising the lettering on the trees and stones.