They are rather tablelands than mountains, for they do not 
reach an elevation, except in some parts of the tableland, of more 
than 100 meters, while the mean elevation of a range of moun- 
tains is 500 meters. 
This geographic district in the State of Matto Grosso is in- 
differently called the cordillara of Parecys, but does not present a 
mountainous aspect except on the South side. On this scarred 
side, the rock is cut into peaks, or cut away into obelisks. On 
the other side towards the Tapajéz and Xingu, a long range ex- 
tends and gradually declines into the plains of the State of 
Amazonas. D’Orbiguy found in the high northern part of Matto 
Grosso, the existence of beds pertaining to the carboniferous age 
and corresponding to rocks of the same nature which on the 
opposite side of that region are found in the Bolivian bases of 
the Sierra of Santa Cruz. After this Hart and Derby verified 
the fact that the southern parts of the Araxa, which are the 
elevated borders of the tableland, date probably from paleozoic 
epochs, and there are found the carboniferous, devonian and 
silurian beds. Fossil beds found by the Geologist Smith below 
the hillocks of the plains, 50 kilometers east of Cuyaba, place 
these facts beyond doubt. More to the North is the zone of 
the rocky places, which in links cut the Madeira, Tapajéz, Xingu, 
Tocatius and their tributaries, the walls denuded by erosion, are 
all of the crystalline formation, granite, ‘gueis, porphory and 
quartzite. The elevations that unroll in the direction of the 
South, between the sources of the Paraguay and Araguaya, fol- 
lowing between the Paraguay and the Parana, do not present the 
same characteristics as the tablelands of the North. The high 
parts of Western Matto Grosso were separated from the East 
and West sides and devastated by lateral excavations, take in 
certain places the aspects of true mountain chains, and for this 
reason they are named, from the North to the South, the Sierras 
of S. Jeronimo, Maracaji and Anhauhaly. 
Eruptive rocks, called basaltic in this country, probably por- 
phyritic rend the beds of sandstone, of which the mountains are 
composed and appear to form by their disintegration “red lands,” 
similar to those which give the farmers of S. Paulo their abun- 
dant harvests of coffee. 
In a sort of circle limited by a semicircle of elevations iso- 
lated masses have been lifted up, rocks whose outlines, seen 
from a distance, have a perfect regularity. The hills proper, for 
the greater part, have geometrical forms, which it should be 
said, great forces have crumbled, leaving smooth walls like the 
sides of pyramids. The tops of the tablelands, as well as summits, 
have been maimed by a force certainly corresponding to 
the other summits, which now may be seen as part of the same 
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