REVIEWS. 855 



After the formation of the fundamental complex of schists, which 

 here consists of metamorphosed marine sediments, there were oro- 

 graphic movements which lifted, folded, and metamorphosed them ; 

 these movements were probably accompanied by granitic eruptions pro- 

 ducing granitic zones and pegmatite dikes. 



The granitoid gneiss zone of the Paranahyba valley and Entre 

 Rios and the amphibole schists probably 1 ^present later granitic 

 and basic eruptions connected with and modified by orogenetic 

 movements. 



After an interval of denudation came the sedimentary deposits 

 which, upon elevation, form the region of schists, sandstones, and 

 Palaeozoic limestones between Santa Luzia and Formoza, and further 

 to the north the lofty (1500 meters), flat-topped Veadeiros. 



This second uplift closed the cycle of great geologic events for 

 this region, and it has ever since been undergoing denudation. In 

 the surrounding region, however, to the north and to the west in the 

 Tocantins-Araguaya and the Xingu and Paraguay basins, to the east 

 in the basin of the Sao Francisco, and to the south in that of the 

 Paranan, enormous sedimentary deposits were laid down, which, by 

 transgression, covered the margins of the old Goyaz island and 

 extended over enormous areas in the basins mentioned. The later 

 deposits have remained in a horizontal position. They seem to have 

 begun in Devonian times and to have gone on with certain interrup- 

 tions up to Mesozoic times. In the mining area about Uberaba the 

 rocks are soft sandstones, and augite porphyries belonging to this 

 great horizontal series. The sandstone is the continuation of the beds 

 which in Sao Paulo overlie fossiliferous Carboniferous or Permian 

 rocks ; it is probably Triassic. 



The characteristic feature of this formation in the Paranan basin is 

 the abundance of eruptive rocks, suggesting a very active volcanic 

 epoch. Denudation has deeply trenched the plateau, leaving a 

 characteristic topography. Wherever erosion has cut down to the 

 harder itacolumites these are left as high and rugged foothills with 

 steep flanks. The limestone also resists erosion better than its asso- 

 ciated rocks. 



The last and newest formation of all these is the top dressing of 

 gravel, which is not a marine deposit, however, but the result of atmos- 

 pheric agents and the deposits of modern streams. 



J. C. Branner. 



