1 COROCORO COPPER DISTRICT OF BOLIVIA 43 



PALEONTOLOGIC EVIDENCE OF THE AGE OF THE RAMOS 



Careful examination of the measured section of the Ramos 

 and of many other localities in those beds failed to yield 

 any organic remains so that we are dependant on previous 

 work for evidence concerning the age of these rocks. 



Indefinite as to locality and uncertain as to identification 

 is the statement by Forbes (p. 38) that he "was informed 

 that a complete Saurian head had been extracted from the 

 same beds by M. Ramon Due, but was not successful in 

 obtaining it nor some fossil bones and teeth now in the 

 museum of Avignon, in France, sent there by M. Grainier, 

 of La Paz." 



Whether the petrified bones, mentioned by Reck, came 

 from the Ramos or not is unknown, but as he supplies no 

 further information concerning them they are of no 

 assistance in the problem at hand. 



Mr. Jose Sossi, formerly owner of the Libertad mine, 

 said that in 1910 he encountered at a depth of 360 feet in 

 that mine a skeleton that he sent to the Dauelsberg Gesell- 

 schaft in Hamburg to be sold. Nothing more is known 

 about it. 



The Ramos shales often show mud-cracked surfaces and 

 at certain horizons contain an abundance of cylindrical, 

 imbricatedly - marked casts of what are apparently the 

 burrows of some organism, One of these is figured on 

 plate 5. Similar mud-cracked surfaces and burrow-like casts 

 also occur in the Desaguadero series, notably at the small 

 quarry along the railroad which furnished the Edentata 

 footprint, thus serving to indicate the same general age of 

 the two series of deposits. 



The only direct paleontologic evidence of the age of the 

 Ramos series is that furnished by the skeleton of Macrau- 

 chenia boliviensis described by Huxley. This was encount- 

 ered during operations in the Santa Rosa mine in 1859, a 

 long distance below the surface and in a normal consolidated 

 matrix. The Haversian canals of the bones were for the 



