That night we had a minimum temperature of 51° Fahr., the elevation of our camp being 2,150 ft.
Naturally, over the expanse of water the sunrise was wonderful. The sky was well covered by feathery radiations from the north-east, which were intersected by striations shooting skyward from east to west and forming a charming design. The radiations from the north-east reached right across the sky as far as the horizon to the south-west. What astonished me most in Matto Grosso was the characteristic immobility of the clouds. In the day-time they remained sometimes for hours with hardly any changes or movement. As soon as the sun appeared, rendering the lower sky of a golden yellow and of vivid Indian red above, the northern part of the lagoon was enveloped in mist, which rose in angular blocks, vertical on the south side, slanting at a sharp angle on the north. These pointed peaks of mist remained immobile—as if they had been solid—until the sun was well up in the sky.
I went once more to gaze at the glorious panorama. In the morning light new and important details were revealed, such as a strange series of dykes of a prismatic shape, of which I could count as many as seven. Great transverse depressions or grooves—from S.S.E. to N.N.W., with a dip S.S.E.—could in that light be now plainly detected, and this time two great square castles of rock—instead of one—were disclosed upon the third range of undulations.
The high ridge to the south-west displayed a subsidence on a large scale in its central portion, where bare vertical red walls had been left standing on each side.
Then there were other curious concave depressions or gateways formed in the great table-land—which had for its marked characteristic concave curves on all its slopes.
On leaving camp—nearly at noon, after a serious quarrel and fight among my men, which left me worried to death by the petty nonsense and incessant grumbling of my followers—we journeyed at an elevation of 2,300 ft., finding shortly after an almost circular cuvette of deep grey cinders, 100 ft. deep (elevation at the bottom 2,200 ft.).
Twelve kilometres farther on we came upon another great depression extending from east to west, with an enormous belt of grassy land. There was the usual cluster of trees and palms in the centre, but larger than usual. To the south were campos—lovely prairies—with sparse and stunted trees—chiefly Goma arabica or acacias.
The elevation of the upper edge of the cuvette was 2,500 ft., that of the bottom 2,450 ft. We continued our journey on the top of the plateau, with slight undulations varying in height from 50 to 70 ft. Snuff-coloured soil and red sand were invariably noticeable on the higher points, and grey ashes in the lower points, where erosion had caused depressions.
Then, farther on, the plateau, with an elevation of 2,450 ft., was absolutely flat for several kilometres, and showed sparse vegetation and miserable-looking anæmic trees—the thin soil over solid rock affording them inadequate nourishment.
Eighteen kilometres from our last camp we came upon another oval basin (elev. 2,400 ft. above the sea level), extending longitudinally from N.N.E. to S.S.W. On its huge deposits of cinders grew deliciously green, fresh-looking, healthy grass, and a thick clump of burity palms, and birero trees of immense height and thick foliage. Those beautiful trees were called by the people of Goyaz "cutibá" and "pintahyba." They were marvellous in their wonderful alignment among the surrounding circle of gorgeous palms. The latter were in their turn screened in their lower part by a belt of low scrub—so that upon looking at that oasis one could hardly realize that it had not been geometrically laid out by the hands of a skilful gardener.
