A GREAT NATURAL ARCH 
a third oval cuvette with a surface layer of ashes, merely 
a continuation of the preceding cuvette . We here resumed 
our northerly course, going through what the Brazilians 
call chapada, or high land scantily wooded. 
To the southwest we had a high plateau with round, 
natural towers of red rock, resembling the walls of a 
fortress. Those red, cylindrical towers stood all along the 
summit of the range, with immense, square blocks of grey 
rock above them in horizontal strata. In the centre of 
that long range could be perceived a double-tiered crater 
and several grottoes. In its northern section the range 
was vertical, with red and yellow rocky walls over 300 
feet high. On the summit of that rocky stratum were 
other strata with a dip to the south. Half way up could 
be observed a red ledge about ten feet thick (also with a 
dip to the south) all along the entire length of the range. 
Colossal blocks and flows of lava were to be seen 300 yards 
east of this range. In one place was an immense, natural 
arch, like the work of a skilful mason. At the northern 
end of the range stood a castle, the work of nature, with 
three square towers, and between them numerous mono¬ 
liths or pillars standing on walls of columnar formation. 
Evidently there was a crater in that northern part, 
the castle-like structure being merely formed by many 
superposed layers of yellow lava. Near the throat of 
the crater the lava was hard baked and of a bluish red 
colour. In the lower section the strata were each six feet 
thick, under a smooth band, absolutely horizontal, one 
hundred feet thick. There were then two top layers, each 
twenty feet thick, and four more layers each four feet 
thick, and slightly wavy. The last ones were somewhat 
shattered, and displayed large blocks moved out of posi¬ 
tion, apparently by a volcanic explosion. 
In going round the northern corner of the range more 
similar buttresses, like towers, were disclosed — I could 
count as many as eight — projecting out of the immense, 
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