597 



strata of the formations that compose it, are so 

 much the more manifest * in the groupe of 

 Brazil. 



Section III. 



Nature of the Rocks.— Relative Age and Super- 

 position of the Formations. — Primitive, tran- 

 sition, secondary , tertiary, and volcanic Soils. 



The preceding section has developed the geo- 

 graphical limits of the formations, the extent of 

 the direction of the zones of gneiss-granite, 

 micaslate-gneiss, clayslate, sandstone, and in- 

 termediary limestone, which come succes- 

 sively to light. It remains to indicate suc- 

 cinctly the nature and relative age of these 

 formations. In order not to confound facts 

 with geognostic opinions, I shall describe these 

 formations without dividing them^ according 

 to the method generally followed, into five 

 groupes of primitive, transition, secondary, 

 tertiary, and volcanic rocks. I was fortunate 

 enough to discover the types of each groupe, in 

 a region where, before my voyage, no rock had 



* According to the manuscript notes of M. d'Esehwege, 

 and his Geogn. Gemalde von Brasilien, p. 6. The strata of 

 the primitive and intermediary rocks of Brazil run very re- 

 gularly., like the Cordillera of Villarica (Serra do Espinhaco) 

 hor. 1*4 or hor. 2 of the compass of Freiberg. (N. 28° E.) 

 The inclination of the strata is generally towards the E.S.E, 



