all a _furnas_ (from the Latin _fornus_)--a
somewhat misapplied term by which they named any deep hollow or chasm,
whether vertical like a precipice or horizontal such as a cave.

It was getting slightly less cold during the nights. On May 24th the
Fahrenheit thermometer registered a minimum of 60 deg. and a maximum
temperature of 75 deg..

Owing to the usual trouble of recovering the mules in the morning we only
left camp at 10.30 a.m., rising over great masses of ferruginous rock,
which showed through the deposits of ashes and sand at an elevation of
1,950 ft. The immense view of the campos in great undulations was really
exquisite to the west and south-west.

My mules were then travelling over a strange narrow strip of rock at a
height of 2,050 ft.--in some places only a few yards across--on the top
of vertical walls dividing two deep valleys, one to the south, very
extensive, with great lava-flows; another to the north. In the latter
valley an immense extinct crater was visible, in three well-defined
internal terraces and a deep central depression.

Upon climbing on the summit of a high conical hill I further discovered
that the crater had an elongated shape, the longest diameter being from
north to south, the southern and lower part being overlapped by a
voluminous flow of lava which also covered a great part of the mountain
slope. Strange monoliths were numerous, among the many fantastically
shaped rocks, and also boulders lying about at all angles. One like a
huge table rested on the top of another, upon which it had fallen with
great force, as could be seen by the vertical splitting of the rock
underneath. The rock above appeared simply broiled--and so were the huge
masses of debris, especially of ferruginous rock, which had evidently
been ejected by that crater. The entire summit of the crater cone (2,100
ft. above the sea level) was of hard black baked rock.

Close by, to the north, was another peculiar oval depression, the highest
part of which to the north-west was in four distinct terraces in the
interior. The eastern part was more flattened, not unlike a huge soup
plate. In the centre was another deep depression--possibly an extinct
crater too. This second crater was to the north of the high-domed crater
described above.

In the near west we had mere undulations over which we gradually
travelled, but the country was getting much more disturbed than it had
appeared since leaving the Araguaya River. Du