STRATIGRAPHIC GEOLOGY 



217 



pagner. Constamment, nous retrouverons ces memes calcaires des deux cotes 

 de la vallee du San-Francisco, et ils apparaissent souvent a la bas d'une 

 depot de gres et de schiste argileux a couches presque horizontales, qui repose 

 sur eux et dans lequel la denudation a creuse le bassin du fleuve et de ses 

 affluents." 



Notes made by Dr. Antonio Olyntho at Lapa do Chnmbo, tive kilo- 

 meters southwest of Sete Lagoas and close to the margin of the Per- 

 mian/^ tell of "nm veeiro de qnartzo encaixotado entre camadas de 

 schisto, tudo intercalado em nma montanha calcarea/' and "As camadas 

 de schisto tem para cima a altnra de 3 a 4 metros, e acima d'elles vem a 



Figure 3. — The Mountains of the Diamond District of Ahaite 



The view is taken from near Toldas, six leagues east of Serra do Barro Yermelho. 



After P. Claussen. 



montanha calcarea.'' These exposures leave no donbt abont the shales 

 and the limestone being interbedded. 



This interbedding of the shales and limestones is noted by all the geol- 

 ogists who have crossed the basin of the upper Eio Sao Francisco, espe- 

 cially on rios Indaia, Borrachndo, Abaete, and on the Sao Francisco. ^^ 

 Particularly impressive and enlightening are the section given by Claus- 

 sen, which is here reproduced,^' and his observations and conclusions in 



35 Antonio Olyntho dos Santos Pires : Viagem aos terrenos diamantiferos do Abaete. 

 Annaes da Escola de Minas, no. 4, pp. 145. 146. Rio de Janeiro, 1885. 



^ See Lisboa, Oliveira, Antonio Olyntho, and Claussen. 



^■^ P. Claussen : Notes geologiques sur la province de Minas Geraes. Bui. Acad. Royal 

 de Bruxelles, vol. viii, no. 5, pi. 1, Brussels, 1841. 



