260 



ANNUAL. REPORT SMITHSONIAN INSTITUTION, 192 8 



Table I. — Geological relations between African Cape Mountains and Argentinian 



Sierras 



AgrandProtero- 

 zoic develop- 

 ment. 



SOUTHERN AND WESTERN CAPE MOUN- 

 TAINS 



[Going up in sequence] 

 Pre-Cambrian systems. Formations 

 marine, continental, and igneous. 

 Primitive. Possibly Archeozoic. 

 Proterozoic: 

 Witwatersrand. 

 Ventersdorp. 

 Transvaal-Nama. > 

 Black Reef. 

 Pretoria. 

 Rooiberg. 



Mountain-making in late Proterozoic; 

 long erosion. 



Waterberg, age unknown. 



Cape system of elastics, 10,000 feet, 

 usually regarded as Devonian. Land 

 on North. 



1. Table Mountain near-shore ss., 



sh., tillites, 5,000 feet: bi- 

 valves not diagnostic; age, 

 Ordovician to Devonian. 

 Disconformity. 



2. Bokkeveld, Lower Devonian, 



sh., ss., 2,500 feet; lower half 

 marine with 130 species; upper 

 half continental. 

 Disconformity. 



3. Witteberg sh., ss., 2,500 feet; 



continental, probably Devon- 

 ian or (?) Lower Carboniferous. 

 Epeirogenic elevation, begun about 

 Middle Devonian time, highest north 

 of 30° S. 

 Great hiatus. 



Karroo system north of Cape Moun- 

 tains, continental elastics, 15,000 

 feet, with terminal volcanics, 4,000 

 feet. Overlap on Cape Mountains. 

 1. "Lower Permian" (Dwyka), 

 lower sh., 700 feet; tillites, 

 1,000 feet; upper sh., 600 

 feet; no coals. Mesosaurus, 

 Noteosaurus. In West, marine 

 Eurydesma beds. 



SIERRAS OF BUENOS AIRES 



Pre-Cambrian crystallines. 

 Undifferentiated. 



Period of mountain-making. 



Ordovician, extensive in sh., Is., ss., no 

 known fossils, but such in pre-Cor- 

 dilleras. 

 Silurian sh. with Arthrophycus harlani. 

 Well developed in northwest Ar- 

 gentina. 



Lower Devonian ss., sh., with limited 

 Bokkeveld fauna. Great develop- 

 ment in northwest Argentina, but 

 without tillites. 



Possibly a time of marked orogeny in 

 later Devonian. 



Great hiatus. 



Permian tillites like Dwyka, inter- 

 bedded with marine strata. No 

 Eurydes7na. 



Mesosaurus in Parand, Noteosaurus in 

 Brazil but none in Argentina. 



