great revolution while in a state of
semi-liquefaction owing to intense heat from fire, after which a sudden
and intense cooling had taken place and covered the country perhaps even
with ice. Whether the immense deposits of ashes and sand had been formed
before or after the glacial period--if any such period ever existed in
that particular region--could be merely a matter of speculation. In many
places the sand, ashes, and red earth had almost consolidated into easily
friable rock.

Where the actual rock was not exposed we had campos, campos, campos,
stretching as far as the eye could see. Far from being monotonous, one
had--or at least I had--a delightful sensation in riding across those
interminable prairies of beautiful green. One could breathe the pure air
with fully expanded lungs, and in that silent, reposeful solitude one
felt almost as if the whole world belonged to one. We were not much
worried by insects on those great open places; it was only on getting
near patches of vegetation and near streams that we suffered from the
attacks of those pests.

We saw few trees--all stunted and weak--as the padding of earth over the
rocky under-strata did not permit their roots to go deep down, and
therefore they grew up with difficulty and anaemic.

Twelve kilometres from the Rio Barreiros we came to a stream (elev. 1,400
ft.). On our left, rising above the inclined campos, was a triple
undulation much higher than its neighbours. To the west stood two twin,
well-rounded mounds, that my men named at once "the woman's breasts,"
which they much resembled.

We were still marching on deep deposits of ashes, and, higher, upon
semi-hardened sandstone. On the northern side the twin hills had a
different shape. They ended in a sharply pointed spur.

After going over an ochre-coloured sandy region (elev. 1,530 ft. above
the sea level) we were again on magnificent undulating campos, dotted
here and there with dark green shrubs and _bosquets_ to the north,
north-west, and north-east.

Beyond, to the north-east, loomed again in the far distance our
mysterious plateau, of a pure cobalt blue where in shadow. As one ran
one's eye along its sky-line it was almost flat for more than half its
length, then came a slight dip, followed by a terraced dome. Then again a
straight line followed by a slightly higher and more undulating sky-line
with three steps in it, and a conical end at its eastern terminus. The
most easterly point of all-