xtensive cluster of trees in the large _cuvette_. Quite low
down--only a hundred feet or so above the top of the trees--there hung a
heavy white cloud. It was a windless day. The cloud ended on all sides
exactly where the trees ended, as sharply as if it had been cut with a
knife. It looked exactly like a rectangular canopy over the luxuriant
vegetation. This appearance was intensified by undulations in the lower
part of the cloud, like festoons.

In proceeding across the immense circular _cuvette_ I found that the
central line of thick vegetation formed an angle. A streamlet of
delicious crystal-like water emerged from among the trees. On its bank
lay the skeletons of three mules, suggesting a tragedy.

On leaving the great _cuvette_ we rose again to the top of the plateau,
2,550 ft. above sea level. On descending from a large dome to the west
over red volcanic sand and red earth, half consolidated into rock easily
friable under slight pressure, we were once more travelling across
immense campos in a depression of fine cinders and earth, extending from
north to south, at an elevation of 2,400 ft. We further traversed two
other less important depressions, the deepest being at an elevation of
2,350 ft.

The jutting headlands of the plateau on which we had travelled were all
most precipitous--nearly vertical--and of solid dark red volcanic rock.

A magnificent view next confronted us to the south. A huge black square
block with a crater was before us, and there appeared what seemed to me
to be the remaining sections of a huge volcanic vent and several smaller
funnels. The lower lip of the crater formed a terrace. Then another wider
crater could be perceived in a circular hollow of the spur of the plateau
on which we had travelled, and which stretched out into the underlying
plain. That spur extended from north-east to south-west, and in it two
circular hollows of great size could be noticed, the sides of which were
deeply fluted.

During the entire march that day we had seen quantities of
violet-coloured deposits made up of tiny crystals, carbonized and
pulverized rock and ferruginous dust.

[Illustration: Central Cluster of Trees and Palms in a Cuvette
(Matto Grosso).]

[Illustration: A Giant Wave of Lava.]

On descending from the summit of the plateau, by a very steep slope, we
saw many shrubs of _sapatinho_, a medicinal plant of the genus
_euphorbiaceae_ (Euphorbia), growing in the interstices of red igneous