THE LAVA FIELD OF THE PARANA BASIN 79 



crystalline highlands, is perhaps the oldest land in South America. 

 The vegetation of the Parana Basin has an archaic cast. Arau- 

 carians, tree ferns, and primitive angiosperms are characteristic. 

 Among old types of animals, we find lung fishes and primitive 

 birds. The Parana Basin may have been one of the centers of 

 development and distribution of the present fauna and flora of 

 South America. 



Latest movements. — Any diastrophic events of possibly later 

 date than pre- Cretaceous will be difficult to detect in the Parana 

 Basin. The Atlantic Coast and the alluvial basin of the River 

 Plate, are more favorable regions for their detection. 



There is great general similarity in stratigraphic, volcanic, and 

 structural features between the Karroo Basin of South Africa and the 

 Parana Basin of South America. The land-laid deposits of the 

 Karroo System of South Africa are very similar in mode of origin 

 and fossil content to those of the Parana Basin. There is a great 

 geosyncHne in South Africa also. Du Toif^ has recently sum- 

 marized the data on the Stromberg volcanic series and comple- 

 mentary doleritic intrusives of South Africa. He says the intrusives 

 cover an area of fully 220,000 square miles between the twenty- 

 eighth and thirty-third parallels, and originally extended eastward 

 into the Indian Ocean and probably westward into the Atlantic. 

 If outlying tracts are connected, the area of intrusions aggregate 

 more than 325,000 square miles. The dolerites probably date 

 from Rhaetic or Lias, at latest from Middle Jura. The effusive 

 outflows of the Stromberg volcanics occupy the central part of 

 the Karroo Basin and are confined to an area 350 miles long and 

 150 miles broad with Basutoland as the center. As du Toit points 

 out, the mid-Mesozoic shows in South America, South Africa, 

 Tasmania, Antarctica, peninsular India and in the eastern United 

 States (Newark series) the greatest known eruptions of trappean 

 rocks. 



April 24, 1922 



» " Karroo Dolerites of South Africa, " etc., Trans Geol. Soc. South Africa, Vol. 



xxni, pp. 1-42. 



